Reynolds Cup 12 (2024)

[Reinhard Kleeberg]

In behalf of the Reynolds Cup Committee:

Subject: Reynold Cup 12 (2024)

Dear All,

Still a short time to register for the 12th (2024) Reynolds Cup.

https://www.clays.org/reynolds-cup-2024/

Samples will be shipped towards the end of March.

If you are serious about quantitative phase analysis, please do  
consider taking up the challenge to blind test your methodology!


Sincerely,
Steve


The James Hutton Institute is a Scottish charitable company limited by  
guarantee.

Registered in Scotland No. SC374831
Registered Office: The James Hutton Institute, Invergowrie, Dundee DD2 5DA.
Charity No. SC041796
_
Reinhard Kleeberg
--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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Re: Misconduct

[Reinhard Kleeberg]

Dear Jon,
thanks a lot for the AI autonomous labs links, very interesting (but  
not much surprising?).


Definitely, a lot of (educational) work must be done on methods, even  
for well introduced and widely used ones. For QPA full profile fitting  
by any Rietveld software, there are many outcomes from the IUCr Round  
robins and, more recently, for of the CMS Reynolds Cup,  
https://link.springer.com/article/10.1346/CCMN.2017.064054

Raven & Self stated:
"The Rietveld method is the most popular technique of choice among  
participants, which is also reflected in the number of successful  
participants who gained the top three places and indeed the ultimate  
winners. The competition has also shown that participants using the  
same software can produce some extraordinarily bad results when used
incorrectly or inappropriately. This is certainly the case for  
participants who used the Rietveld method with an

overly large proportion of the worst performers using this technique."
Regarding the "automated mineralogy" community, I don't think their  
crisis is related purely to blind trusting in AI based methods. There  
must be also a general lack in education about the basics of analytics  
and chemometry.

Greetings

Reinhard


Zitat von Jonathan WRIGHT :


On 17/01/2024 09:40, Reinhard Kleeberg wrote:

"Automated mineralogy"


Dear Colleagues,

It sounds like there crisis for this community? I didn't see anyone  
mention the AI story that was also in the news:


https://www.chemistryworld.com/news/new-analysis-raises-doubts-over-autonomous-labs-materials-discoveries/4018791.article

https://chemrxiv.org/engage/chemrxiv/article-details/65957d349138d231611ad8f7

Perhaps there is still a lot of interesting work to be done on methods?

With best regards,

Jon



--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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Re: Misconduct

[Reinhard Kleeberg]

Dear Alan,
exactly, knowledge gaps and laziness do often cause blind trust in any  
black box or statistical methods.
And, as AI is trained by open internet resources, the older bad  
science rubbish will be probably perpetuated by AI. Bad perspectives  
for science.
Terminology: We all know that automation in phase analysis  
(qualitative and quantitative) has a tradition over decades, also in  
applied mineralogy, and especially with XRPD methods. From this point  
of view, the use of the term "Automated mineralogy" for any SEM/EDX  
based methods sounds quite ignorant and arrogant to me.

Greetings

Reinhard

Zitat von Alan W Hewat :


Dear Rienhard
Yes everything is AI now, and people often prefer that to thinking for
themselves. I have nothing against automation as a human aid, but there is
a temptation with "black box" software to just click the "Refine
Everything" button and copy-paste the results. There is a problem when AI
is also responsible for reviewing and publishing this "science" :-)
Alan.

On Wed, 17 Jan 2024 at 09:37, Reinhard Kleeberg <
kleeb...@mineral.tu-freiberg.de> wrote:


Dear Alan,
I agree completely, especially with the evaluation of the "quality" of
the paper triggering the discussion.

Regarding misleading and capturing terminology in analytical methods,
I have an IMHO more serious, horrible example:
"Automated mineralogy"
https://en.wikipedia.org/wiki/Automated_mineralogy
what is very popular in a big community of geologists and aggressively
advertised, despite of nether any chemometric evaluation by
interlabory tests was published, phase abundances are given to second
to forth decimal digit of mass% and analytical errors resp. esd's are
typically not published. But even here we probably have already lost
the battle for precise terminology and quality of analytics, as people
can present such data and terminology in several journals of applied
geology and mineral processing without any problem.

Reinhard

Zitat von Alan W Hewat :

> Yes Stefan, it is a question of what you are refining and constraining.
> Before Rietveld it was of course known that the positions of the peaks
were
> determined by the unit cell. There were techniques like Search-Match that
> attempted to identify materials by the positions of the peaks. The
history
> of phase analysis is older than Rietveld. The Petten group were not
> interested in QPA, but instead in refining the crystal and magnetic
> structures of specific materials.
>
> If Rietveld had never existed, it is reasonable to assume that QPA would
> still have evolved much as it has today, refining the phase content from
> the whole profile, without trying to refine structures of mixed phases.
>
> And for those who worry about pedantry, "Rietveld Refinement" is just
> shorthand for the "Rietveld (method of) Refinement. It involves the
> refinement of the crystal structure, not Rietveld :-)
>
> Finally Kurt, perhaps as individuals we can't change the world, but if we
> are concerned that people are debasing our scientific techniques, we can
> expose them as Armel did. Or at least we can refuse to co-author such
> papers, and reject them as journal editors. As authors and referees we
can
> correct sloppy use of terminology. This paper is wrong on so many levels,
> apart from the apparent "misconduct" and the incorrect label of Rietveld
> Refinement.
> 
> Dr Alan Hewat, NeutronOptics
> Grenoble, FRANCE (from phone)
> alan.he...@neutronoptics.com
> +33.476984168 VAT:FR79499450856
> http://NeutronOptics.com/hewat
> ___
>
>
> On Tue, 16 Jan 2024, 15:50 Stefan Seidlmayer, 
wrote:
>
>> Dear all,
>>
>> I was following the discussion also with great interest, as terminology
is
>> important to distinguish properly between different items.
>>
>> To my understanding the Rietveld approach was new because it constrained
>> the fitting of a peak list generated "from a structure" with the
refinement
>> of the profile of the peaks themselves.
>>
>> Thus I would have the impression that everytime when we use a
>> constrainement of peak list which is generated from a structure and do
not
>> refine a list of "individual peaks" it is a Rietveld-type refinement.
>>
>> A Profile Refinement is/was in my current understanding, when the
>> peak/reflection position is not constrained by the structure parameters,
>> but can be refined in an arbitrary way, individual for each
peak/reflection.
>> From the positions refined in this way, one could then determine cell
>> parameter etc. But this would require a secondary step. First refine all
>> found peaks/reflection with a common prof

Re: Misconduct

[Reinhard Kleeberg]

Dear Alan,
I agree completely, especially with the evaluation of the "quality" of  
the paper triggering the discussion.


Regarding misleading and capturing terminology in analytical methods,  
I have an IMHO more serious, horrible example:

"Automated mineralogy"
https://en.wikipedia.org/wiki/Automated_mineralogy
what is very popular in a big community of geologists and aggressively  
advertised, despite of nether any chemometric evaluation by  
interlabory tests was published, phase abundances are given to second  
to forth decimal digit of mass% and analytical errors resp. esd's are  
typically not published. But even here we probably have already lost  
the battle for precise terminology and quality of analytics, as people  
can present such data and terminology in several journals of applied  
geology and mineral processing without any problem.


Reinhard

Zitat von Alan W Hewat :


Yes Stefan, it is a question of what you are refining and constraining.
Before Rietveld it was of course known that the positions of the peaks were
determined by the unit cell. There were techniques like Search-Match that
attempted to identify materials by the positions of the peaks. The history
of phase analysis is older than Rietveld. The Petten group were not
interested in QPA, but instead in refining the crystal and magnetic
structures of specific materials.

If Rietveld had never existed, it is reasonable to assume that QPA would
still have evolved much as it has today, refining the phase content from
the whole profile, without trying to refine structures of mixed phases.

And for those who worry about pedantry, "Rietveld Refinement" is just
shorthand for the "Rietveld (method of) Refinement. It involves the
refinement of the crystal structure, not Rietveld :-)

Finally Kurt, perhaps as individuals we can't change the world, but if we
are concerned that people are debasing our scientific techniques, we can
expose them as Armel did. Or at least we can refuse to co-author such
papers, and reject them as journal editors. As authors and referees we can
correct sloppy use of terminology. This paper is wrong on so many levels,
apart from the apparent "misconduct" and the incorrect label of Rietveld
Refinement.

Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 VAT:FR79499450856
http://NeutronOptics.com/hewat
___


On Tue, 16 Jan 2024, 15:50 Stefan Seidlmayer,  wrote:


Dear all,

I was following the discussion also with great interest, as terminology is
important to distinguish properly between different items.

To my understanding the Rietveld approach was new because it constrained
the fitting of a peak list generated "from a structure" with the refinement
of the profile of the peaks themselves.

Thus I would have the impression that everytime when we use a
constrainement of peak list which is generated from a structure and do not
refine a list of "individual peaks" it is a Rietveld-type refinement.

A Profile Refinement is/was in my current understanding, when the
peak/reflection position is not constrained by the structure parameters,
but can be refined in an arbitrary way, individual for each peak/reflection.
From the positions refined in this way, one could then determine cell
parameter etc. But this would require a secondary step. First refine all
found peaks/reflection with a common profile. Then determine the lattice
parameters from the refined peak positions etc.
This is also troublesome as without prior structure "knowledge" it may and
surely is that certain reflection which in fact are overlapping multiple
reflections are improperly identified as "one" reflection.
This is very the neatness of the Rietveld approach comes into play, as it
generates even overlapping reflections which then generate the total
profile by constraining them with the profile parameters.

So the main point in differentiation is then in my eyes:
Rietveld-Refinement: The use of a structure generated peak list which is
constrained with profile parameters.

Profile-Refinement: Profile refinement can work on individual peaks with
NO structure information at all.

Pawley-Refinement then is logically a little bit of a Hybrid, as the
reflection list is pre-generated from the structure. But the intensities
are just matched to best fit the profile. While in a true Rietveld even the
reflection intensities is always generated from the underlying structure
model applied in the Rietveld refinement.

What do you think of this point of view? Am I overlooking something?

Best regards

Stefan Seidlmayer



Am Di., 16. Jan. 2024 um 15:23 Uhr schrieb Alan W Hewat <
alan.he...@neutronoptics.com>:


Ha ! When Terry Sabine proposed to call it Rietveld Refinement, I told
him that Rietveld was already "refined".


Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 

Re: Misconduct

[Reinhard Kleeberg]

Hi Alan,
in general, I could agree your strict definition, reducing the term  
"structure refinement" to atomic coordinates as the main goal.
Hm, "QPA profile refinement" sounds a bit diffuse. What about "QPA  
full pattern profile refinement", resp. "QPA whole powder pattern  
refinement"? Just to include any peak shifting models (e.g. lattice  
parameters), the Fhkl lists, and to separate from single line profile  
fitting methods? Will give an impressive abbreviation in any papers...  
;-)
However, as long as the QPA people are (mis?)using the same software  
tools as the true crystal structure research community, and as long as  
such software was generally put into the "Rietveld" box, I don't  
believe that a more precise terminology for this approach will finally  
have any chance in practical use. Even if the IUCr would redefine the  
terminology and would be able to keep it strictly consistent in their  
own journals: The method was so widely introduced in other fields and  
industries in the last decades under the "Rietveld" label that there  
will be no way back to the roots.

Best regards

Reinhard

Zitat von Alan W Hewat :


Dear Kurt. No, refining just cell parameters doesn't qualify as Rietveld
refinement :-) Certainly Hill/Howard (1987) and Bish/Howard made important
contributions to QPA, but there were earlier papers eg *Werner et al
(1979) * https://scripts.iucr.org/cgi-bin/paper?a18098 that you might also
reference
*"Quantitative analysis of multicomponent powders by full-profile
refinement of Guinier-Hägg X-ray film data"*
So call it QPA Profile Refinement or something similar.

The revolution of Rietveld Refinement was to refine structural parameters
directly to fit the measured profile data. That broke with a long
crystallographic "belief" that it was necessary to first determine
"structure factors" (Bragg intensities), requiring many more parameters,
with their correlations. Attributing all profile refinement to Rietveld, is
not correct, and hides the importance of Rietveld Refinement, which was
hotly contested and not generally accepted by the wider x-ray
crystallographic community for 10+ years
Sakata and Cooper (1979) An analysis of the Rietveld refinement method
https://scripts.iucr.org/cgi-bin/paper?a18236
Without wanting to start another argument, look at the van Laar and Schenk
historical reference list, even if you don't accept their interpretation.
https://journals.iucr.org/a/issues/2018/02/00/ib5058/#BB29

Alan

Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 VAT:FR79499450856
http://NeutronOptics.com/hewat
___


On Tue, 16 Jan 2024, 09:34 Reinhard Kleeberg, <
kleeb...@mineral.tu-freiberg.de> wrote:


What is Rietveld refinement? Does "Rietveld" QPA exist?
Hill & Howard (1987) titled "QPA from Neutron Powder Diffraction Data
Using the Rietveld Method" and indeed they refined all structural
parameters of their simple phases in binary mixtures, a methodical
test of the approach.

However, the primary goal in QPA "refinement" is to reach an
acceptable fit without running into wrong scale factors. Therefore,
peak positions, profile shapes and all structural factors potentially
biasing the scale factors must be either refined or known previously.
If everything is known, just scale factors must be "refined", may be
by a linear optimization (published since the 1980ies for experimental
patterns), no "Rietveld" code is necessary.
IMHO such simple approach can work well only under very fortunate and
simple/well known circumstances.
However, in routine QPA especially of geological materials of unknown
origin (minerals with not always exactly known chemistry and
microstructure) we typically need to optimize, begining from any
published and selected structure models
- lattice parameters (always)
- profile parameters (always), often with complicated profile models
due to disorder, anisotropic line broadening, bimodal size/microstrain
distribution etc.
- most intensity relevant site occupation (Mg-Fe substitution, K
content of interlayers in micas...), sometimes constrained to lattice
parameters
- PO correction models (if necessary).
As commonly the atomic positions of minerals are often well known from
single crystal work and small deviations do not have a significant
impact on the total scale factors, the atomic coordinates are
typically fixed in QPA. As Debye-Waller factors are hard to refine
from diffraction patterns with limited angular range and for minor
components, it is necessary to fix them in routine work. This means
they must be known exactly (literature?, refined separately (if pure
material is available), or estimated.

So Alan, is the refinement of one site occupation factor in a QPA by
using a Rietveld softwa

Re: Misconduct

[Reinhard Kleeberg]

What is Rietveld refinement? Does "Rietveld" QPA exist?
Hill & Howard (1987) titled "QPA from Neutron Powder Diffraction Data  
Using the Rietveld Method" and indeed they refined all structural  
parameters of their simple phases in binary mixtures, a methodical  
test of the approach.


However, the primary goal in QPA "refinement" is to reach an  
acceptable fit without running into wrong scale factors. Therefore,  
peak positions, profile shapes and all structural factors potentially  
biasing the scale factors must be either refined or known previously.  
If everything is known, just scale factors must be "refined", may be  
by a linear optimization (published since the 1980ies for experimental  
patterns), no "Rietveld" code is necessary.
IMHO such simple approach can work well only under very fortunate and  
simple/well known circumstances.
However, in routine QPA especially of geological materials of unknown  
origin (minerals with not always exactly known chemistry and  
microstructure) we typically need to optimize, begining from any  
published and selected structure models

- lattice parameters (always)
- profile parameters (always), often with complicated profile models  
due to disorder, anisotropic line broadening, bimodal size/microstrain  
distribution etc.
- most intensity relevant site occupation (Mg-Fe substitution, K  
content of interlayers in micas...), sometimes constrained to lattice  
parameters

- PO correction models (if necessary).
As commonly the atomic positions of minerals are often well known from  
single crystal work and small deviations do not have a significant  
impact on the total scale factors, the atomic coordinates are  
typically fixed in QPA. As Debye-Waller factors are hard to refine  
from diffraction patterns with limited angular range and for minor  
components, it is necessary to fix them in routine work. This means  
they must be known exactly (literature?, refined separately (if pure  
material is available), or estimated.


So Alan, is the refinement of one site occupation factor in a QPA by  
using a Rietveld software enough "structure" to label such analysis as  
"Rietveld QPA"? Or, is refining cell parameters an acceptable criterion?

If not, any idea for a better name?

Greetings

Reinhard


Zitat von Alan W Hewat :


Yes, it's Rietveld Refinement if you refine the atomic structure
parameters. If you define the Rietveld method as simply the calculation of
the powder pattern, that applies to just about any powder diffraction
study, and under values the importance of the method.

But you shouldn't refine structure parameters just to get a better fit in
QPA by Powder Profile Refinement. I don't know how often you find entirely
new compounds in QPA, and can determine their structure well enough to
publish them as new compounds.

The R-factor in this study is impressively low, but it is meaningless as
Armel has shown.


Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from phone)
alan.he...@neutronoptics.com
+33.476984168 VAT:FR79499450856
http://NeutronOptics.com/hewat
___


On Mon, 15 Jan 2024, 18:01 Kurt Leinenweber,  wrote:


Hi, in our work we still sometimes encounter entirely new compounds with
simple structures like rocksalt, spinel, etc.  in order to convince
ourselves and our readers that the materials are real, we have to fit the
powder patterns - put in the atoms, refine lattice parameter(s), show that
thermal parameters are reasonable, fit the peak shapes, background etc all
together.  In the case of spinels for example we can also refine the single
atomic parameter and show that the bond lengths are reasonable.  The
refinements are used to decide whether sites are fully occupied and to
decide the valence of the cation when multiple valence states are possible.
It’s not the kind of thing that would get people really excited with the
crystallographic methods, but it is necessary for convincing ourselves and
others that the identification of the compound is reasonable.  Is that
Rietveld refinement?  I don’t know so I call upon the list to say.

Kurt

Get Outlook for iOS 
--
*From:* rietveld_l-requ...@ill.fr  on behalf
of Matthew Rowles 
*Sent:* Sunday, January 14, 2024 11:04:25 PM
*To:* Alan W Hewat 
*Cc:* Le Bail Armel ; Rietveld_L <
Rietveld_L@ill.fr>
*Subject:* Re: Misconduct

I see the core contribution of the Rietveld method as the point-wise
calculation of a powder pattern. This then enables the refinement of the
parameters.

Yes, attributing QPA to Rietveld is incorrect; that is mainly due to
Hill/Howard and Bish/Howard - I try to make it a point to differentiate
this.

calling PDF refinements Rietveld refinements is just plain wrong (afaik),
unless you actually are moving crystallographic parameters around, in which
case, the nomenclature gets fuzzy..

On Sat, 13 Jan 2024 at 14:39, Alan W Hewat 
wrote:

The core of Rietveld 

Re: NIST-676a

[Reinhard Kleeberg]

If CR1 is added as internal standard (20 mass%) to rock samples prior  
to McCrone milling and flat powder samples for Bragg-Brentano are  
carefully prepared, we did not observe severe preferred orientation  
for the corundum, maybe as the powder is fine enough  
(particles/aggregates ~ 1 µm before milling) to be randomly  
distributed in the mixture within the gaps between the coarser mineral  
grains.
But as Jim mentioned, the profile shape of CR1 is suboptimal, we need  
a bimodal crystallite size distribution model to fit. Anyway, for  
routine QPA the material is working.

Best regards

Reinhard

Zitat von Daniel Chateigner 20210513 :


and not textured ?

Le 14/11/2023 à 12:56, Reinhard Kleeberg a écrit :

Hi Jim,
great news, would be good to have a corundum what can be modelled  
with an easier profile shape model.

Best regards

Reinhard

Zitat von "Cline, James P. Dr. (Fed)" :


Hi all,

SRM 676a consisted of Baikowski CR1.  This material is of a  
non-ideal crystallite size distribution: quite broad with tales to  
large crystallites.  SRM 676b was custom made for us by Baikowski  
with a more uniform crystallite size distribution in the 200 nm  
region.  We are working on the certification, rather complex, see:  
doi:10.1107/S0108767311014565 .  It seems that modern beamlines  
don't favor the large specimen size needed for our experiments.   
We have good data from one source, we are looking for some from  
another as we like to see results from more one machine.


Jim


James P. Cline
Materials Measurement Science Division
National Institute of Standards and Technology
100 Bureau Dr. stop 8370 [ B113 / Bldg 217 ]
Gaithersburg, MD 20899-8523    USA
james.cl...@nist.gov
https://www.nist.gov/people/james-p-cline (301) 975 5793

-Original Message-
From: rietveld_l-requ...@ill.fr  On  
Behalf Of Reinhard Kleeberg

Sent: Monday, November 13, 2023 1:51 AM
To: rietveld_l@ill.fr
Subject: Re: NIST-676a

We are using Baikowski CR1
https://www.baikowski.com/en/serie/cr/ Not certified but maybe  
identical with SRM676a. Scale factors and cell parameters found to  
be within the errors. Profile shape shows similar features (also  
not an ideal material).

Best regards
Reinhard


Zitat von Matthew Rowles :


Hi Matej

You can try IMS135 - high purity alumina.

https://imst/
andards.com.au%2Fproducts%2F=05%7C01%7Cjames.cline%40nist.gov%7C2
d945a33db074232a69808dbe414ca9a%7C2ab5d82fd8fa4797a93e054655c61dec%7C1
%7C0%7C638354550207433666%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAi
LCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=r
MK%2BzDuAMv2q7U6fCpu38mzuqIrTdCiQfNDPSmB%2BQZk%3D=0

It was certified against some SRM676a we already had in the lab.


Matthew




On Sun, 12 Nov 2023 at 22:42, Matej Dolenec  wrote:


Dear all,

I am trying to buy NIST-676a but unfortunately unsuccessful ... I was
trying to find it on NIST, ALDRICH and other sites but the standard
is out of stock. Does anybody has any information if this standard
will be available soon and where? If not, which standard should I use
instead of NIST-676a? I was using this standard for amorphous  
phase identification.


Regrads, Matej

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Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129




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Professeur Normandie Universite
http://www.ecole.ensicaen.fr/~chateign/danielc/
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Re: NIST-676a

[Reinhard Kleeberg]

Hi Jim,
great news, would be good to have a corundum what can be modelled with  
an easier profile shape model.

Best regards

Reinhard

Zitat von "Cline, James P. Dr. (Fed)" :


Hi all,

SRM 676a consisted of Baikowski CR1.  This material is of a  
non-ideal crystallite size distribution: quite broad with tales to  
large crystallites.  SRM 676b was custom made for us by Baikowski  
with a more uniform crystallite size distribution in the 200 nm  
region.  We are working on the certification, rather complex, see:  
doi:10.1107/S0108767311014565 .  It seems that modern beamlines  
don't favor the large specimen size needed for our experiments.  We  
have good data from one source, we are looking for some from another  
as we like to see results from more one machine.


Jim


James P. Cline
Materials Measurement Science Division
National Institute of Standards and Technology
100 Bureau Dr. stop 8370 [ B113 / Bldg 217 ]
Gaithersburg, MD 20899-8523USA
james.cl...@nist.gov
https://www.nist.gov/people/james-p-cline
(301) 975 5793

-Original Message-
From: rietveld_l-requ...@ill.fr  On  
Behalf Of Reinhard Kleeberg

Sent: Monday, November 13, 2023 1:51 AM
To: rietveld_l@ill.fr
Subject: Re: NIST-676a

We are using Baikowski CR1
https://www.baikowski.com/en/serie/cr/
Not certified but maybe identical with SRM676a. Scale factors and  
cell parameters found to be within the errors. Profile shape shows  
similar features (also not an ideal material).

Best regards
Reinhard


Zitat von Matthew Rowles :


Hi Matej

You can try IMS135 - high purity alumina.

https://imst/
andards.com.au%2Fproducts%2F=05%7C01%7Cjames.cline%40nist.gov%7C2
d945a33db074232a69808dbe414ca9a%7C2ab5d82fd8fa4797a93e054655c61dec%7C1
%7C0%7C638354550207433666%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAi
LCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C=r
MK%2BzDuAMv2q7U6fCpu38mzuqIrTdCiQfNDPSmB%2BQZk%3D=0

It was certified against some SRM676a we already had in the lab.


Matthew




On Sun, 12 Nov 2023 at 22:42, Matej Dolenec  wrote:


Dear all,

I am trying to buy NIST-676a but unfortunately unsuccessful ... I was
trying to find it on NIST, ALDRICH and other sites but the standard
is out of stock. Does anybody has any information if this standard
will be available soon and where? If not, which standard should I use
instead of NIST-676a? I was using this standard for amorphous  
phase identification.


Regrads, Matej

++
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54655c61dec%7C1%7C0%7C638354550207433666%7CUnknown%7CTWFpbGZsb3d8eyJW
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%7C%7C%7C=nnVgkFx8mHZ%2Br%2Bng9oJ00Uz9wBy9MYDZ%2F46l%2F3%2BUGg8
%3D=0
++





--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129



--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

++
Please do NOT attach files to the whole list 
Send commands to  eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++

Re: NIST-676a

[Reinhard Kleeberg]

We are using Baikowski CR1
https://www.baikowski.com/en/serie/cr/
Not certified but maybe identical with SRM676a. Scale factors and cell  
parameters found to be within the errors. Profile shape shows similar  
features (also not an ideal material).

Best regards
Reinhard


Zitat von Matthew Rowles :


Hi Matej

You can try IMS135 - high purity alumina.

https://imstandards.com.au/products/

It was certified against some SRM676a we already had in the lab.


Matthew




On Sun, 12 Nov 2023 at 22:42, Matej Dolenec  wrote:


Dear all,

I am trying to buy NIST-676a but unfortunately unsuccessful ... I was
trying to find it on NIST, ALDRICH and other sites but the standard is
out of stock. Does anybody has any information if this standard will be
available soon and where? If not, which standard should I use instead of
NIST-676a? I was using this standard for amorphous phase identification.

Regrads, Matej

++
Please do NOT attach files to the whole list 
Send commands to  eg: HELP as the subject with no body
text
The Rietveld_L list archive is on
http://www.mail-archive.com/rietveld_l@ill.fr/
++





--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

++
Please do NOT attach files to the whole list 
Send commands to  eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++

Re: FPSM : (was Re: [EXT] [External] Re: Step-like basline)

[Reinhard Kleeberg]

e online), works also with  
turbostratic and modulated clay structures using your model (the  
Ufer et al.) to simulate them in the Rietveld. It is a fantastic  
trick that I use for texture analysis but also quantification and  
now in FPSM. Having a quick Rietveld help to search-match samples  
containing clays using data even at high angles (more than 60  
degs). I indeed don’t pre-calculate and store structures because  
when you work with many of them it takes more time to load all the  
precalculations from a database (even the speedy ones) than to  
re-calculate everything.


So I am glad we both made use of each other models/ideas!

Best regards,

Luca

<http://www.unitn.it/>
logo_unitrento_firma.png

*
Luca Lutterotti*
Dipartimento di Ingegneria Industriale
Università di Trento
via Sommarive, 9 - 38123 Trento (Italy)
tel. +39 0461 2824-14 (Office), -34 (X-Ray lab)


ico_fb_32x32.pngico_twitter_32x32.pngico_insta_32x32.pngico_linkedin_32x32.pngico_youtube_32x32.png

Maud: http://maud.radiographema.com <http://maud.radiographema>



On 5 Sep 2023, at 13:49, Reinhard Kleeberg  
 wrote:


Dear Luca,
I completely agree and will be very happy to have a 1D detector  
with sufficient energy resolution to resolve a "pure" Cu Kalpha1/2  
doublet from W Lalpha1. This would make routine work much easier.  
IMHO, the biggest improvements in XRPD instrumentation within the  
last decades came solely from the detector side, should be  
continued.


Regarding search-match by Rietveld: Your FSPM method is a very  
inspiring idea. Nicola Doebelin has incorporated a simplified  
approach in PROFEX, too:
https://www.youtube.com/watch?v=Oqj71TiifeI  
<https://www.youtube.com/watch?v=Oqj71TiifeI>


I'm routinely applying a run of ~500 structures/minerals what we  
are commonly using (+- the former QPA database of Seifert AUTOQUAN  
or from the BGMN webpage) for a phase screening of unknown  
samples, needs ~ 5 min without interaction. Than running QPA  
refinement with the best matching structures, clicking on  
remaining peaks in the difference plot for getting a proposal of  
best matching main line positions in the database, and adding  
these structure(s) to the refinement, running again... This is a  
typical workflow in our lab, no need for peak search, background  
treatment, thinking about artifact peaks...


Best regards

Reinhard

Zitat von Luca Lutterotti <mailto:luca.luttero...@unitn.it>>:



Dear Reinhard and Rietvelders,

It is always a compromise. Ideally we would like the fastest  
instrument with a lot of intensity (so, 1D or 2D detectors) but  
no lines outside the Kalpha or even just the Kapha1 like the one  
of James Cline. But this means a monochromator on the incident  
beam and you get fluorescence background. Now I like your  
solution of the Si Drift detector, so you just cut the  
fluorescence and you don’t need the monochromator in the first  
place.
So we are working and we are testing some lab prototypes of a 1D  
Si Drift like detector to get the best of both world. It is only  
a lot of electronic, but one day we will have wonderful  
instrument with only the lines we need and no fluorescence for  
the background. Actually we use fluorescence for the chemical  
analysis (quantitative).


About the search-match problem. Have a look on our FPSM method (
http://fpsm.radiographema.com/ <http://fpsm.radiographema.com/>)  
where we don’t care about extra lines as it is a Rietveld  
search-match. We don’t need to identify or search peaks. We don’t  
use peak positions, we just fit with the Rietveld. It is slower  
indeed, but every day is becoming faster and in a few years it  
will run quickly on our cellphones (I have a prototype running  
there).


Best regards,

Luca

<http://www.unitn.it/ <http://www.unitn.it/>>

Luca Lutterotti
Dipartimento di Ingegneria Industriale
Università di Trento
via Sommarive, 9 - 38123 Trento (Italy)
tel. +39 0461 2824-14 (Office), -34 (X-Ray lab)




Maud:http://maud.radiographema.com  
<http://maud.radiographema.com/><http://maud.radiographema/  
<http://maud.radiographema/>>




Begin forwarded message:

From: Reinhard Kleeberg 
Subject: Re: [EXT] [External] Re: Step-like basline
Date: 5 September 2023 at 08:56:15 CEST
To: rietveld_l@ill.fr
Reply-To: Reinhard Kleeberg 

Dear Luca,
I completely agree with your opinion, and want to add that even  
for "trivial" tasks in XRPD like phase analysis and standard  
Rietveld refinements the satellites/spectral impurities do cause  
significant trouble:


- The K beta and W L satellites of strong peaks of major phases  
like quartz, carbonates or cubic structures in geomaterials are  
typically not automatically recognized in the standard peak  
search procedures and therefore misinterpreted to be K alpha  
peaks and added to the peak list. I can't tell you how often I  
was asked from colleagues for explanation of such "unident

Re: Step-like basline

[Reinhard Kleeberg]

Hm, as Philips systems at this time always had combined a  
scintillation counter with a diffracted beam graphite 002 bent  
monochromator, the question arises how the W L series and Cu Kbeta  
lines could reach the detector... Bad quality of the graphite mosaic  
crystal?


Reinhard

Zitat von Le Bail Armel :


The muscovite data is dated 1996 from an old Philips 1710 diffractometer,

vertical sample holder, scintillation counter, not much used because we

had better instruments, hence this stupid test ;-)

Armel


envoyé : 7 septembre 2023 à 10:57
de : Reinhard Kleeberg 
à : rietveld_l@ill.fr
objet : Re: Step-like basline

Dear Luca,
sorry, I don't understand the "mosaic crystal" eplanation, especially
not the "non-centre position" issue. IMHO, when the pattern was
measured at a "powder" Bragg-Brentano configuration, in reflection
mode, axial and equatorial divergence maximum ~ 2 degree, the 00l
series of all misoriented crystal blocks can fulfill the diffraction
condition only within the range of the instruments divergence, and the
parafocusing arrangement would reflect such blocks back very close to
the nominal angular position (as it is the case for a powder as well).
So single crystal reflection of big blocks should only be observable
within the total profile of a "normal" ideal powder peak (the
"instrumental" profile"). This is indeed what we see if coarsely
crystalline materials (e.g. quartz sand) are measured on a typical
powder diffractometer: Such peaks are extremely sharp, sometimes split
or doubled, sometimes with "wrong" alpha1/2 intensity ratio, or may
have small additional maxima and may be "edges" in their slopes,
depending on the number or size of crystals, but all these effects are
very close to the correct maximum position (+- <1 degree). So I can't
imagine that the unknown satellites in the mica pattern are
"misoriented-displaced" Cu Kalpha 00l peaks?

Armel, what type of detector was used for this measurement? If the W L
series was detected, probably no diffracted beam monochromator, and no
Peltier cooled Si drift detector? If so, even more spectral
contamination may come into account. For example, I remember to have
complained about a new Co tube (no company names here) showing
systematic satellites ~ 1 % intensity from standard Si and LaB6 powder
measurements. The wavelength recalculated by Bragg's law was Zn Kalpha
(!!!), confirmed by spectral analysis, the tube Co target was
obviously contaminated. As the satellites in your example in the < 0.x
% magnitude of the Cu K alpha1 intensity, even quite low contamination
of other elements than W may be the source. So it could be
interesting to calculate wavelengths from all positions of the unknown
satellites for the d-spacings of the mica 00l series and see if any
calculated wavelengths do repeat.

Another thought:
Here we have a single crystal of muscovite. As some of the unexplained
peaks appear to be extremely sharp, what about Renninger (multiple
diffraction) hkl peaks? Maybe there are enough lattice planes in the
monoclinic mica structure to give a chance for multiple diffraction to
get registered by a divergent beam (Bragg-Brentano) configuration?
Such peak positions appear to be unsystematic, with no relatiion to
the Cu Kalpha 00l.

However, a take-home message of your example should be: Do never
measure single crystals in parafocusing geometry without safely
monochromatic radiation ;-)

Best regards

Reinhard

Zitat von Luca Lutterotti :


It is call graininess, as Miguel said before, these are mosaic
single crystals and depending on your source (divergence, spot
dimension at different angles etc.) you get each mosaic crystal to
create a diffraction peak that especially at low two-theta angle may
be displaced a lot from its theoretical position because it is
diffracting from a non center position. This is what you get also
when you analyse samples with extremely large grains. If you use a
2D detector instead of scanning with a point or small psd, you will
see all these individual grain or mosaic crystals diffracting around
their ideal spot or if it is a sample with just large grains,
distributed around the Laue circle. More the grain is on a lateral
position respect to the center of the beam, more it is displaced in
two-theta. At higher angle your beam size on the sample is smaller
and there is less displacement for geometrical reasons.
I like to work with 2D detectors (texture, stresses) because it is
easy to see these “figures”.
In addition you have the spectral impurities identified by Frank and
you may get some small grains with different orientation and twins
that will create some of the non 00l peaks.
Analysing these kind of patterns would require a sophisticated
simulation of the grains-crystals distribution and computing like
ray-tracing for the geometrical effects. Not worth it. Single
crystals and sharp textures require

Re: Step-like basline

[Reinhard Kleeberg]

Dear Luca,
sorry, I don't understand the "mosaic crystal" eplanation, especially  
not the "non-centre position" issue. IMHO, when the pattern was  
measured at a "powder" Bragg-Brentano configuration, in reflection  
mode, axial and equatorial divergence maximum ~ 2 degree, the 00l  
series of all misoriented crystal blocks can fulfill the diffraction  
condition only within the range of the instruments divergence, and the  
parafocusing arrangement would reflect such blocks back very close to  
the nominal angular position (as it is the case for a powder as well).  
So single crystal reflection of big blocks should only be observable  
within the total profile of a "normal" ideal powder peak (the  
"instrumental" profile"). This is indeed what we see if coarsely  
crystalline materials (e.g. quartz sand) are measured on a typical  
powder diffractometer: Such peaks are extremely sharp, sometimes split  
or doubled, sometimes with "wrong" alpha1/2 intensity ratio,  or may  
have small additional maxima and may be "edges" in their slopes,  
depending on the number or size of crystals, but all these effects are  
very close to the correct maximum position (+- <1 degree). So I can't  
imagine that the unknown satellites in the mica pattern are  
"misoriented-displaced" Cu Kalpha 00l peaks?


Armel, what type of detector was used for this measurement? If the W L  
series was detected, probably no diffracted beam monochromator, and no  
Peltier cooled Si drift detector? If so, even more spectral  
contamination may come into account. For example, I remember to have  
complained about a new Co tube (no company names here) showing  
systematic satellites ~ 1 % intensity from standard Si and LaB6 powder  
measurements. The wavelength recalculated by Bragg's law was Zn Kalpha  
(!!!), confirmed by spectral analysis, the tube Co target was  
obviously contaminated. As the satellites in your example in the < 0.x  
% magnitude of the Cu K alpha1 intensity, even quite low contamination  
of other elements than W may be the source.  So it could be  
interesting to calculate wavelengths from all positions of the unknown  
satellites for the d-spacings of the mica 00l series and see if any  
calculated wavelengths do repeat.


Another thought:
Here we have a single crystal of muscovite. As some of the unexplained  
peaks appear to be extremely sharp, what about Renninger (multiple  
diffraction) hkl peaks? Maybe there are enough lattice planes in the  
monoclinic mica structure to give a chance for multiple diffraction to  
get registered by a divergent beam (Bragg-Brentano) configuration?  
Such peak positions appear to be unsystematic, with no relatiion to  
the Cu Kalpha 00l.


However, a take-home message of your example should be: Do never  
measure single crystals in parafocusing geometry without safely  
monochromatic radiation ;-)


Best regards

Reinhard





Zitat von Luca Lutterotti :

It is call graininess, as Miguel said before, these are mosaic  
single crystals and depending on your source (divergence, spot  
dimension at different angles etc.) you get each mosaic crystal to  
create a diffraction peak that especially at low two-theta angle may  
be displaced a lot from its theoretical position because it is  
diffracting from a non center position. This is what you get also  
when you analyse samples with extremely large grains. If you use a  
2D detector instead of scanning with a point or small psd, you will  
see all these individual grain or mosaic crystals diffracting around  
their ideal spot or if it is a sample with just large grains,  
distributed around the Laue circle. More the grain is on a lateral  
position respect to the center of the beam, more it is displaced in  
two-theta. At higher angle your beam size on the sample is smaller  
and there is less displacement for geometrical reasons.
I like to work with 2D detectors (texture, stresses) because it is  
easy to see these “figures”.
In addition you have the spectral impurities identified by Frank and  
you may get some small grains with different orientation and twins  
that will create some of the non 00l peaks.
Analysing these kind of patterns would require a sophisticated  
simulation of the grains-crystals distribution and computing like  
ray-tracing for the geometrical effects. Not worth it. Single  
crystals and sharp textures requires a point beam to avoid these  
effects. And a monochromatic one.


Best regards,

Luca

 

Luca Lutterotti
Dipartimento di Ingegneria Industriale
Università di Trento
via Sommarive, 9 - 38123 Trento (Italy)
tel. +39 0461 2824-14 (Office), -34 (X-Ray lab)




Maud: http://maud.radiographema.com 



On 6 Sep 2023, at 17:43, Le Bail Armel  wrote:

Dear Frank,

Same as you. I have not a complete solution.

Best

Armel


envoyé : 6 septembre 2023 à 16:57
de : Frank Girgsdies >
à : Le Bail Armel 

Re: [EXTERNAL] Re: [EXT] [External] Re: Step-like basline

[Reinhard Kleeberg]

Dear Radovan,
may be you are right, but this great development will unfortunately  
not help the big number of lab diffractionists to puzzle the patterns  
to be analyzed in their daily business ;-)

Best regards

Reinhard

Zitat von Radovan Cerny :


Dear Reinhard,

I wouldn't say "solely from the detector side". The biggest  
improvement is synchrotron radiation (+2D detectors邏).


Best greetings from Lac Leman

Radovan Cerny

Envoyé à partir de Outlook pour Android<https://aka.ms/AAb9ysg>

From: rietveld_l-requ...@ill.fr  on  
behalf of Reinhard Kleeberg 

Sent: Tuesday, September 5, 2023 1:49:57 PM
To: rietveld_l@ill.fr 
Subject: [EXTERNAL] Re: [EXT] [External] Re: Step-like basline

Dear Luca,
I completely agree and will be very happy to have a 1D detector with
sufficient energy resolution to resolve a "pure" Cu Kalpha1/2 doublet
from W Lalpha1. This would make routine work much easier. IMHO, the
biggest improvements in XRPD instrumentation within the last decades
came solely from the detector side, should be continued.

Regarding search-match by Rietveld: Your FSPM method is a very
inspiring idea. Nicola Doebelin has incorporated a simplified approach
in PROFEX, too:
https://www.youtube.com/watch?v=Oqj71TiifeI

I'm routinely applying a run of ~500 structures/minerals what we are
commonly using (+- the former QPA database of Seifert AUTOQUAN or from
the BGMN webpage) for a phase screening of unknown samples, needs ~ 5
min without interaction. Than running QPA refinement with the best
matching structures, clicking on remaining peaks in the difference
plot for getting a proposal of best matching main line positions in
the database, and adding these structure(s) to the refinement, running
again... This is a typical workflow in our lab, no need for peak
search, background treatment, thinking about artifact peaks...

Best regards

Reinhard

Zitat von Luca Lutterotti :


Dear Reinhard and Rietvelders,

It is always a compromise. Ideally we would like the fastest
instrument with a lot of intensity (so, 1D or 2D detectors) but no
lines outside the Kalpha or even just the Kapha1 like the one of
James Cline. But this means a monochromator on the incident beam and
you get fluorescence background. Now I like your solution of the Si
Drift detector, so you just cut the fluorescence and you don’t need
the monochromator in the first place.
So we are working and we are testing some lab prototypes of a 1D Si
Drift like detector to get the best of both world. It is only a lot
of electronic, but one day we will have wonderful instrument with
only the lines we need and no fluorescence for the background.
Actually we use fluorescence for the chemical analysis (quantitative).

About the search-match problem. Have a look on our FPSM method (
http://fpsm.radiographema.com/) where we don’t care about extra
lines as it is a Rietveld search-match. We don’t need to identify or
search peaks. We don’t use peak positions, we just fit with the
Rietveld. It is slower indeed, but every day is becoming faster and
in a few years it will run quickly on our cellphones (I have a
prototype running there).

Best regards,

Luca

 <http://www.unitn.it/>

Luca Lutterotti
Dipartimento di Ingegneria Industriale
Università di Trento
via Sommarive, 9 - 38123 Trento (Italy)
tel. +39 0461 2824-14 (Office), -34 (X-Ray lab)




Maud: http://maud.radiographema.com <http://maud.radiographema/>



Begin forwarded message:

From: Reinhard Kleeberg 
Subject: Re: [EXT] [External] Re: Step-like basline
Date: 5 September 2023 at 08:56:15 CEST
To: rietveld_l@ill.fr
Reply-To: Reinhard Kleeberg 

Dear Luca,
I completely agree with your opinion, and want to add that even for
"trivial" tasks in XRPD like phase analysis and standard Rietveld
refinements the satellites/spectral impurities do cause significant
trouble:

- The K beta and W L satellites of strong peaks of major phases
like quartz, carbonates or cubic structures in geomaterials are
typically not automatically recognized in the standard peak search
procedures and therefore misinterpreted to be K alpha peaks and
added to the peak list. I can't tell you how often I was asked from
colleagues for explanation of such "unidentified peaks", and how
much time people have spent for searching for explanation of such
artefact lines.
- In Rietveld analysis our software must generate the peaks at
least for the measured angular range. Depending on the method how
the software is doing this, we run into problems with the
satellites. If the software generates the reflections from the
positions of K alpha peaks from the start lattice parameters and
the (extended) upper measured angle, K beta satellites of K alpha
peaks outside this angular range will maybe not generated and
remain unfitted in the pattern. If the software generates the peaks
depending on the shortest wavelength in the wavelength profile
(more intelligent a

Re: [EXT] [External] Re: Step-like basline

[Reinhard Kleeberg]

Dear Luca,
I completely agree and will be very happy to have a 1D detector with  
sufficient energy resolution to resolve a "pure" Cu Kalpha1/2 doublet  
from W Lalpha1. This would make routine work much easier. IMHO, the  
biggest improvements in XRPD instrumentation within the last decades  
came solely from the detector side, should be continued.


Regarding search-match by Rietveld: Your FSPM method is a very  
inspiring idea. Nicola Doebelin has incorporated a simplified approach  
in PROFEX, too:

https://www.youtube.com/watch?v=Oqj71TiifeI

I'm routinely applying a run of ~500 structures/minerals what we are  
commonly using (+- the former QPA database of Seifert AUTOQUAN or from  
the BGMN webpage) for a phase screening of unknown samples, needs ~ 5  
min without interaction. Than running QPA refinement with the best  
matching structures, clicking on remaining peaks in the difference  
plot for getting a proposal of best matching main line positions in  
the database, and adding these structure(s) to the refinement, running  
again... This is a typical workflow in our lab, no need for peak  
search, background treatment, thinking about artifact peaks...


Best regards

Reinhard

Zitat von Luca Lutterotti :


Dear Reinhard and Rietvelders,

It is always a compromise. Ideally we would like the fastest  
instrument with a lot of intensity (so, 1D or 2D detectors) but no  
lines outside the Kalpha or even just the Kapha1 like the one of  
James Cline. But this means a monochromator on the incident beam and  
you get fluorescence background. Now I like your solution of the Si  
Drift detector, so you just cut the fluorescence and you don’t need  
the monochromator in the first place.
So we are working and we are testing some lab prototypes of a 1D Si  
Drift like detector to get the best of both world. It is only a lot  
of electronic, but one day we will have wonderful instrument with  
only the lines we need and no fluorescence for the background.  
Actually we use fluorescence for the chemical analysis (quantitative).


About the search-match problem. Have a look on our FPSM method (
http://fpsm.radiographema.com/) where we don’t care about extra  
lines as it is a Rietveld search-match. We don’t need to identify or  
search peaks. We don’t use peak positions, we just fit with the  
Rietveld. It is slower indeed, but every day is becoming faster and  
in a few years it will run quickly on our cellphones (I have a  
prototype running there).


Best regards,

Luca

 <http://www.unitn.it/>

Luca Lutterotti
Dipartimento di Ingegneria Industriale
Università di Trento
via Sommarive, 9 - 38123 Trento (Italy)
tel. +39 0461 2824-14 (Office), -34 (X-Ray lab)




Maud: http://maud.radiographema.com <http://maud.radiographema/>



Begin forwarded message:

From: Reinhard Kleeberg 
Subject: Re: [EXT] [External] Re: Step-like basline
Date: 5 September 2023 at 08:56:15 CEST
To: rietveld_l@ill.fr
Reply-To: Reinhard Kleeberg 

Dear Luca,
I completely agree with your opinion, and want to add that even for  
"trivial" tasks in XRPD like phase analysis and standard Rietveld  
refinements the satellites/spectral impurities do cause significant  
trouble:


- The K beta and W L satellites of strong peaks of major phases  
like quartz, carbonates or cubic structures in geomaterials are  
typically not automatically recognized in the standard peak search  
procedures and therefore misinterpreted to be K alpha peaks and  
added to the peak list. I can't tell you how often I was asked from  
colleagues for explanation of such "unidentified peaks", and how  
much time people have spent for searching for explanation of such  
artefact lines.
- In Rietveld analysis our software must generate the peaks at  
least for the measured angular range. Depending on the method how  
the software is doing this, we run into problems with the  
satellites. If the software generates the reflections from the  
positions of K alpha peaks from the start lattice parameters and  
the (extended) upper measured angle, K beta satellites of K alpha  
peaks outside this angular range will maybe not generated and  
remain unfitted in the pattern. If the software generates the peaks  
depending on the shortest wavelength in the wavelength profile  
(more intelligent approach), the software must generate much more  
reflections (with maxima outside the measured angular range) and  
all these peaks must be calculated over an extremely broad angular  
range. In the case of low symmetry structures with big cells or  
disordered structures described by partial structure factors and  
the resulting extreme high numbers of peaks, the "extension effect"  
will cause significantly prolonged time for calculations, without  
any positive effect.


That's why I prefer to use instrumentation with better  
monochromatic radiation (monochromators, high energy resolution  
detectors) even in the daily bus

Re: [EXT] [External] Re: Step-like basline

[Reinhard Kleeberg]

Dear Francois,
even older XRPD people may be confused by any satellites, especially  
when switching from "traditional" instrumentation (e.g. graphite  
monochromator + szinti) towards "modern" instruments, my personal  
experience ;-)


Thanks for your documents, very helpful. The table containing the  
tungsten L series peaks is included in the PROFEX software also, at  
least the wavelengths without intensities. One can go to PROFEX menue  
Edit-Preferences-Cursors and activate the wavelengths for display with  
the spectral line cursor. I typically routinely check the W Lalpha1,  
the most intense one, when analysing data from 1D detectors or unknown  
instruments.


Regarding traditional peak search software:
Old ones do simply search for any maxima on 2theta and apply Bragg's  
law, assuming monochromatic radiation.
But if the instrument is known and the spectral features including  
impurities are included in the wavelength model, not only Rietveld  
profile refinement can be improved: The convolution-based  
("Fundamental parameter") peak model can be used also in a peak search  
procedure by independent peak fitting ("Parrish fitting"). Joerg  
Bergmann had written an algorithm "EFLECH" in the 1980ies, see  
literature [1] at

http://www.bgmn.de/methods.html.
This software EFLECH is now included in the PROFEX software for peak  
search, see:

https://www.youtube.com/watch?v=acMK2z7d_QY
Here, spectral impurities can not get misinterpreted, as they are part  
of the fit model.


Young people may be interested in Nicola Doebelin's video channel:
https://www.youtube.com/@profextutorials2325/videos

Best regards

Reinhard




Zitat von francois Goutenoire :


Dear everyone,

A very nice discussion to help young people in the field of powder  
diffraction.
In our case we are the happy user of two "quick and dirty"  
diffractometers (no brand of course !)
but with two different radiations : copper and cobalt with  
respectively Nickel and Iron K filter + Modern strip detector
Then in order to check for chemical or spectral pollution ?  we  
combine the both set of data in order to check and explain all the  
peaks.

Otherwise, we use Topas V5 to calculate all the tungstene pollution.
Sometimes many with some old X-ray tube (4 years !)
To help you few documents ( sorry some are in french).
https://perso.univ-lemans.fr/~fgouten/Spectral_Pollution

Best wishes François

Le 05/09/2023 à 08:56, Reinhard Kleeberg a écrit :

Dear Luca,
I completely agree with your opinion, and want to add that even for  
"trivial" tasks in XRPD like phase analysis and standard Rietveld  
refinements the satellites/spectral impurities do cause significant  
trouble:


- The K beta and W L satellites of strong peaks of major phases  
like quartz, carbonates or cubic structures in geomaterials are  
typically not automatically recognized in the standard peak search  
procedures and therefore misinterpreted to be K alpha peaks and  
added to the peak list. I can't tell you how often I was asked from  
colleagues for explanation of such "unidentified peaks", and how  
much time people have spent for searching for explanation of such  
artefact lines.
- In Rietveld analysis our software must generate the peaks at  
least for the measured angular range. Depending on the method how  
the software is doing this, we run into problems with the  
satellites. If the software generates the reflections from the  
positions of K alpha peaks from the start lattice parameters and  
the (extended) upper measured angle, K beta satellites of K alpha  
peaks outside this angular range will maybe not generated and  
remain unfitted in the pattern. If the software generates the peaks  
depending on the shortest wavelength in the wavelength profile  
(more intelligent approach), the software must generate much more  
reflections (with maxima outside the measured angular range) and  
all these peaks must be calculated over an extremely broad angular  
range. In the case of low symmetry structures with big cells or  
disordered structures described by partial structure factors and  
the resulting extreme high numbers of peaks, the "extension effect"  
will cause significantly prolonged time for calculations, without  
any positive effect.


That's why I prefer to use instrumentation with better  
monochromatic radiation (monochromators, high energy resolution  
detectors) even in the daily business of phase analysis. We do use  
our 1D detector Mythen2 with Fe filter (Co radiation) only for  
"quick and dirty" measurements.


Best regards

Reinhard


Zitat von Luca Lutterotti :


Dear Habib,

Reinhard is right, and what he explained is exactly what you  
observed. Now I would add that I may not define your Bruker clean  
and optimised, because for this kind of samples, wafers and  
extremely textured thin films, it would be better to have 

Re: [EXT] [External] Re: Step-like basline

[Reinhard Kleeberg]

Dear Luca,
I completely agree with your opinion, and want to add that even for  
"trivial" tasks in XRPD like phase analysis and standard Rietveld  
refinements the satellites/spectral impurities do cause significant  
trouble:


- The K beta and W L satellites of strong peaks of major phases like  
quartz, carbonates or cubic structures in geomaterials are typically  
not automatically recognized in the standard peak search procedures  
and therefore misinterpreted to be K alpha peaks and added to the peak  
list. I can't tell you how often I was asked from colleagues for  
explanation of such "unidentified peaks", and how much time people  
have spent for searching for explanation of such artefact lines.
- In Rietveld analysis our software must generate the peaks at least  
for the measured angular range. Depending on the method how the  
software is doing this, we run into problems with the satellites. If  
the software generates the reflections from the positions of K alpha  
peaks from the start lattice parameters and the (extended) upper  
measured angle, K beta satellites of K alpha peaks outside this  
angular range will maybe not generated and remain unfitted in the  
pattern. If the software generates the peaks depending on the shortest  
wavelength in the wavelength profile (more intelligent approach), the  
software must generate much more reflections (with maxima outside the  
measured angular range) and all these peaks must be calculated over an  
extremely broad angular range. In the case of low symmetry structures  
with big cells or disordered structures described by partial structure  
factors and the resulting extreme high numbers of peaks, the  
"extension effect" will cause significantly prolonged time for  
calculations, without any positive effect.


That's why I prefer to use instrumentation with better monochromatic  
radiation (monochromators, high energy resolution detectors) even in  
the daily business of phase analysis. We do use our 1D detector  
Mythen2 with Fe filter (Co radiation) only for "quick and dirty"  
measurements.


Best regards

Reinhard


Zitat von Luca Lutterotti :


Dear Habib,

Reinhard is right, and what he explained is exactly what you  
observed. Now I would add that I may not define your Bruker clean  
and optimised, because for this kind of samples, wafers and  
extremely textured thin films, it would be better to have a  
monochromator in the incident beam and not a Ni filtered (I would  
more say it is a requirement). It was already showed many times in  
the past as a monochromator in the incident beam is a necessity for  
this materials to avoid all the "physical artifacts" created by the  
strong intensity and not clean Kalpha radiation.


Best regards,

Luca

 <http://www.unitn.it/>

Luca Lutterotti
Dipartimento di Ingegneria Industriale
Università di Trento
via Sommarive, 9 - 38123 Trento (Italy)
tel. +39 0461 2824-14 (Office), -34 (X-Ray lab)




Maud: http://maud.radiographema.com <http://maud.radiographema/>


On 4 Sep 2023, at 12:20, Habib Boughzala  
 wrote:


Many thanks Reinhard,

That's exactly what I wanted to say by  "I can assure that our  
Bruker D8 is clean and optimized!"
Otherwise, in some other cases of well conditioned thin film no  
similar phenomenon is observed!

So, yes, it's obviously possible that your point of view is right.

Regards
Habib


-- Message d'origine --
De "Reinhard Kleeberg" <mailto:kleeb...@mineral.tu-freiberg.de>>

À "Habib Boughzala" mailto:boughz...@yahoo.com>>
Cc rietveld_l@ill.fr <mailto:rietveld_l@ill.fr>
Date 04/09/2023 11:07:50
Objet Re: Re[2]: [EXT] Re: [External] Re: Step-like basline


Dear Habib,
the phenomenom "satellites or edges" originates from the  
diffraction process. The critical parameters are:
- spectral pureness of the primary beam (primary beam  
monochromator, tube spectral contamination like W...)

- the use of K beta absorbtion filter (and its thickness)
- the energy resolution ("window") of the detector system.
Even a D8 system may be equipped with different types of  
detectors, slits and energy limits can be set differently for an  
identical configuration, and quite often satellite peaks may  
appear later in the time of use (aging of the tube produces more W  
L, Fe filters may corrode and get perforated...). So it is  
strictly recommended to check the instrument peridically, by  
measuring a full pattern of a profile standard (LaB6 or Si or  
similar).

Greetings
Reinhard

Zitat von Habib Boughzala <mailto:boughz...@yahoo.com>>:



Dear all,
I would like to send you my witness related to this kind of observation.
I can assure that our Bruker D8 is clean and optimized!

In many cases of well conditioned thin film (spin coating or  
controlled diffusion) material this kind of phenomenon is visible  
around the high

Re: Step-like basline

[Reinhard Kleeberg]

Habib,
obviously your instrument is equipped with a not cooled solid state 1D  
detector (maybe Bruker Lynxeye?) and a Ni filter what is used for  
"selective" absorbtion of the Cu K beta radiation.
What you see in the pattern is mainly a significant part of the tube  
emission spectrum, diffracted at the Si 111 plane, and modified by the  
Ni K absorption edge.
The peak at ~ 25.8 ° is the remnant Si 111 diffracting the Cu Kbeta1  
wavelength 1.39223 A.
The edge is the Ni K absorbtion edge (I don't know the wavelength of  
the edge exactly, ~ 1.49 A), and the doublet at ~ 28.4 ° is the Si 111  
diffracting the Cu K alpha1 and alpha2, 1.54059 and 1.54443 A,  
respectively.
The asymmetric slope of the background on the rigth side of the peak  
is the unfiltered part of the Bremsstrahlung, their low energy part  
what is not more cut by the Ni absorbtion.
As your wafer is a perfect Si 111 plane you get extreme intensity and  
< 1 % intensity effects become clearly visible. Maybe you have seen a  
Si powder pattern what appeared to be "clean", but if you would have  
measured the powder pattern with better counting statistics, your Si  
111 region would look quite similar.

Greetings

Reinhard

Zitat von Habib Boughzala :


Dear all,
I would like to send you my witness related to this kind of observation.
I can assure that our Bruker D8 is clean and optimized!

In many cases of well conditioned thin film (spin coating or  
controlled diffusion) material this kind of phenomenon is visible  
around the highest reflection, especially when the preferred  
orientation is drastically present.


So, in my opinion, Reinhard and Alan are right,  and what is  
observed is just like reflections broadening, asymmetry, shifting  
...etc ... and can be related to the material behavior.
Now, what is the physical (crystallographic!) property responsible  
of this phenomenon? let's open the floor for a large discussion.



Habib



--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

++
Please do NOT attach files to the whole list 
Send commands to  eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++

Re: Re[2]: [EXT] Re: [External] Re: Step-like basline

[Reinhard Kleeberg]

Dear Habib,
the phenomenom "satellites or edges" originates from the diffraction  
process. The critical parameters are:
- spectral pureness of the primary beam (primary beam monochromator,  
tube spectral contamination like W...)

- the use of K beta absorbtion filter (and its thickness)
- the energy resolution ("window") of the detector system.
Even a D8 system may be equipped with different types of detectors,  
slits and energy limits can be set differently for an identical  
configuration, and quite often satellite peaks may appear later in the  
time of use (aging of the tube produces more W L, Fe filters may  
corrode and get perforated...). So it is strictly recommended to check  
the instrument peridically, by measuring a full pattern of a profile  
standard (LaB6 or Si or similar).

Greetings
Reinhard

Zitat von Habib Boughzala :


Dear all,
I would like to send you my witness related to this kind of observation.
I can assure that our Bruker D8 is clean and optimized!

In many cases of well conditioned thin film (spin coating or  
controlled diffusion) material this kind of phenomenon is visible  
around the highest reflection, especially when the preferred  
orientation is drastically present.


So, in my opinion, Reinhard and Alan are right,  and what is  
observed is just like reflections broadening, asymmetry, shifting  
...etc ... and can be related to the material behavior.
Now, what is the physical (crystallographic!) property responsible  
of this phenomenon? let's open the floor for a large discussion.



Habib


-- Message d'origine --
De "Alan W Hewat" 
À "Reinhard Kleeberg" 
Cc rietveld_l@ill.fr
Date 04/09/2023 09:29:08
Objet Re: [EXT] Re: [External] Re: Step-like basline

Reinhard is right that it is best to improve the instrument to  
produce cleaner data. I'm concerned about the advice to model all  
kinds of features whose origin is not fully understood, simply to  
obtain a better fit. Shay has told us nothing about his instrument  
or his conditions of data collection. He asks "Is it a sample  
preparation problem", to which the obvious reply is "Do you see  
this with other samples or different materials" ? Only he can  
answer that. If the answer is yes, he might try modifying his  
instrument (remove filters etc) to see what effect that has on the  
pattern from a simple well characterised material. Again only he  
can do that. Data collection is an experimental science, and data  
refinement should not be reduced to a "black box" computer program  
where extra parameters can be added to reduce the R-factor.

Alan.

On Mon, 4 Sept 2023 at 08:18, Reinhard Kleeberg  
 wrote:

Can be modeled in the BGMN peak profile model as well, by modifying
the *.lam file by a series of additional Lorentzians on the 1/lambda
scale, see figure.
The same can be done for other spectral impurities, e.g. W L
satellites. Also "electronic effects" on the wavelength distribution
profile like the "edges" from the ROI settings of Si drift detectors
can be modelled in such a convolution based approach.
However, better to have a pure/simple wavelength distribution (clear
alpha1/2 doublet) by a monochromator or high energy resolution
detector, as any satellites make trouble in trace phase analysis and
do cause prolonged calculation time in complicated Rietveld refinements.

Reinhard



Zitat von Matthew Rowles :


Topas can model them quite well. The functionality was introduced in
version 5.

On Mon, 4 Sep 2023, 00:54 Kurt Leinenweber,  wrote:


Hi,  Are these things modeled in Rietveld programs, by chance?  It seems
like a lot of baggage to put in a refinement but if it makes the results
better…



   - Kurt



*From:* rietveld_l-requ...@ill.fr  *On Behalf
Of *Thomas Gegan
*Sent:* Sunday, September 3, 2023 9:16 AM
*To:* Bish, David L ; Shay Tirosh ;
Fernando Igoa 
*Cc:* Rietveld List (rietveld_l@ill.fr) 
*Subject:* RE: [EXT] Re: [External] Re: Step-like basline



I agree with a Ni absorption edge, possibly with a Kβ peak around 38° 2θ.



*Tom Gegan*
Chemist III



Phone: +1 732 205-5111, Email: tom.ge...@basf.com
Postal Address: BASF Corporation, , 25 Middlesex Essex Turnpike, 08830
Iselin, United States



*From:* rietveld_l-requ...@ill.fr  *On Behalf
Of *Bish, David L
*Sent:* Sunday, September 3, 2023 7:08 AM
*To:* Shay Tirosh ; Fernando Igoa <
fer.igoa.1...@gmail.com>
*Cc:* Rietveld List (rietveld_l@ill.fr) 
*Subject:* [EXT] Re: [External] Re: Step-like basline



Some people who received this message don't often get email from
b...@indiana.edu. Learn why this is important
<https://urldefense.com/v3/__https:/aka.ms/LearnAboutSenderIdentification__;!!IKRxdwAv5BmarQ!fFhSHn4S5iEzkW-O9lvWG-OzoqK_2SKhRniGa71nxuOL3GcxiyD83i2mnNN0Z48HPkn4zjKqH-aqqA$>

Hello Shay,

I think it is probably related to "tube tails". You can read  
about this in

the literature (e.g., on the BGMN web s

Re: [EXT] Re: [External] Re: Step-like basline

[Reinhard Kleeberg]

Alan, I'm quite sure that Shay's pattern shows the typical profile for  
a profile standard or any "highly crystalline" material measured with  
a standard configuration of his instrument. No problem with sample  
prep, no chance for improvement by modified instrumental setting  
(thicker filter would reduce K beta but make the Ni absorbtion edge  
more prominent). Unfortunately, lab instruments with "fast" 1D  
detectors with high intensity efficiency but bad energy resolution  
demanding for K beta filtering seem to be now the "quasi standard" on  
the market. Low noise patterns can be measured in short time, but the  
distorted profiles are hard to fit by simple standard profiles in a  
similar quality. From this point of view it makes sense to find a  
working approach for fitting the data of such machines, too.


However, I got several measurements showing Co or Cu K beta remnants  
from users despite the manufacturer has claimed that the good energy  
resolution of their detector (no names here!) alone would remove K  
beta "completely". Sometimes the customers were adviced by the company  
cases to insert an additional filter, and the "edge problem" is back...


Btw, I learned that even traditional secondary-beam curved graphite  
002 monochromators are not always able to resolve a completely "clean"  
Cu K alpha1/2 doublet: As the W L alpha wavelength is close to Cu K  
alpha, in unfortunate cases (crystal quality or alignment) even such  
machines may produce measurable/visible W L satellites when old tubes  
are in use. For economic reasons, some people prefer to add a scalable  
W L satellite peak in the BGMN wavelength model instead of buying a  
new tube...


Personally, I love my Peltier cooled 0D Si drift detectors. They  
really can completely suppress K beta and even remove any W L from Cu  
K alpha, no need for scalable satellite peaks in the profile model.  
Just some minor "wavelength feets" must be added to approximate the  
ROI window. Practically, the profiles are comparable with the ones  
obtained by a classical well aligned graphite monochromator plus  
szintillation counter, but with 5 times more intensity. And the  
detector may be used for some qualitative XRF (of course elements from  
K- only, as in air).


Reinhard

Zitat von Alan W Hewat :


Reinhard is right that it is best to improve the instrument to produce
cleaner data. I'm concerned about the advice to model all kinds of features
whose origin is not fully understood, simply to obtain a better fit. Shay
has told us nothing about his instrument or his conditions of data
collection. He asks "Is it a sample preparation problem", to which
the obvious reply is "Do you see this with other samples or different
materials" ? Only he can answer that. If the answer is yes, he might try
modifying his instrument (remove filters etc) to see what effect that has
on the pattern from a simple well characterised material. Again only he can
do that. Data collection is an experimental science, and data refinement
should not be reduced to a "black box" computer program where extra
parameters can be added to reduce the R-factor.
Alan.

On Mon, 4 Sept 2023 at 08:18, Reinhard Kleeberg <
kleeb...@mineral.tu-freiberg.de> wrote:


Can be modeled in the BGMN peak profile model as well, by modifying
the *.lam file by a series of additional Lorentzians on the 1/lambda
scale, see figure.
The same can be done for other spectral impurities, e.g. W L
satellites. Also "electronic effects" on the wavelength distribution
profile like the "edges" from the ROI settings of Si drift detectors
can be modelled in such a convolution based approach.
However, better to have a pure/simple wavelength distribution (clear
alpha1/2 doublet) by a monochromator or high energy resolution
detector, as any satellites make trouble in trace phase analysis and
do cause prolonged calculation time in complicated Rietveld refinements.

Reinhard



Zitat von Matthew Rowles :

> Topas can model them quite well. The functionality was introduced in
> version 5.
>
> On Mon, 4 Sep 2023, 00:54 Kurt Leinenweber,  wrote:
>
>> Hi,  Are these things modeled in Rietveld programs, by chance?  It seems
>> like a lot of baggage to put in a refinement but if it makes the results
>> better…
>>
>>
>>
>>- Kurt
>>
>>
>>
>> *From:* rietveld_l-requ...@ill.fr  *On
Behalf
>> Of *Thomas Gegan
>> *Sent:* Sunday, September 3, 2023 9:16 AM
>> *To:* Bish, David L ; Shay Tirosh ;
>> Fernando Igoa 
>> *Cc:* Rietveld List (rietveld_l@ill.fr) 
>> *Subject:* RE: [EXT] Re: [External] Re: Step-like basline
>>
>>
>>
>> I agree with a Ni absorption edge, possibly with a Kβ peak around 38°
2θ.
>>
>>
>>
>> *Tom Gegan*
>>

Re: [EXT] Re: [External] Re: Step-like basline

[Reinhard Kleeberg]

Can be modeled in the BGMN peak profile model as well, by modifying  
the *.lam file by a series of additional Lorentzians on the 1/lambda  
scale, see figure.
The same can be done for other spectral impurities, e.g. W L  
satellites. Also "electronic effects" on the wavelength distribution  
profile like the "edges" from the ROI settings of Si drift detectors  
can be modelled in such a convolution based approach.
However, better to have a pure/simple wavelength distribution (clear  
alpha1/2 doublet) by a monochromator or high energy resolution  
detector, as any satellites make trouble in trace phase analysis and  
do cause prolonged calculation time in complicated Rietveld refinements.


Reinhard



Zitat von Matthew Rowles :


Topas can model them quite well. The functionality was introduced in
version 5.

On Mon, 4 Sep 2023, 00:54 Kurt Leinenweber,  wrote:


Hi,  Are these things modeled in Rietveld programs, by chance?  It seems
like a lot of baggage to put in a refinement but if it makes the results
better…



   - Kurt



*From:* rietveld_l-requ...@ill.fr  *On Behalf
Of *Thomas Gegan
*Sent:* Sunday, September 3, 2023 9:16 AM
*To:* Bish, David L ; Shay Tirosh ;
Fernando Igoa 
*Cc:* Rietveld List (rietveld_l@ill.fr) 
*Subject:* RE: [EXT] Re: [External] Re: Step-like basline



I agree with a Ni absorption edge, possibly with a Kβ peak around 38° 2θ.



*Tom Gegan*
Chemist III



Phone: +1 732 205-5111, Email: tom.ge...@basf.com
Postal Address: BASF Corporation, , 25 Middlesex Essex Turnpike, 08830
Iselin, United States



*From:* rietveld_l-requ...@ill.fr  *On Behalf
Of *Bish, David L
*Sent:* Sunday, September 3, 2023 7:08 AM
*To:* Shay Tirosh ; Fernando Igoa <
fer.igoa.1...@gmail.com>
*Cc:* Rietveld List (rietveld_l@ill.fr) 
*Subject:* [EXT] Re: [External] Re: Step-like basline



Some people who received this message don't often get email from
b...@indiana.edu. Learn why this is important


Hello Shay,

I think it is probably related to "tube tails". You can read about this in
the literature (e.g., on the BGMN web site) and you can model it in some
Rietveld software such as Topas. You don't normally notice this but it
becomes apparent with higher-intensity peaks.



Regards,

Dave
--

*From:* rietveld_l-requ...@ill.fr  on behalf
of Fernando Igoa 
*Sent:* Sunday, September 3, 2023 3:06 AM
*To:* Shay Tirosh 
*Cc:* Rietveld List (rietveld_l@ill.fr) 
*Subject:* [External] Re: Step-like basline



This message was sent from a non-IU address. Please exercise caution when
clicking links or opening attachments from external sources.



Hey Shay,



Are you using a motorized slit during the measurement? These may open up
abruptly to compensate for the angular dependence of the footprint and thus
generate an abrupt increase in the intensity.



Hope it helps :)



On Sun, Sep 3, 2023, 8:50 AM Shay Tirosh  wrote:

Dear Rietvelders

I am attaching a zoom-in on a diffraction profile.

My question is what is the origin of the step-like profile next to a very
large reflection peak?

Is it a sample preparation problem?

Is it part of the baseline?

Thanks

Shay

--











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--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129
++
Please do NOT attach files to the whole list 
Send commands to  eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++

Re: Software re-binned PD data

[Reinhard Kleeberg]

The problem of falsified counting statistics (deviating from Poisson 
distribution) sometimes arises even from (wrong) conversion of 0D 
detector data (typically when originally cps have been stored and the 
counting time got lost in the conversion), and is quite common when 1D 
detector data are exported to 3rd party formats and the number of active 
channels is not considered correctly in the export routine.


As a tool for a quick coarse check of the correct noise (like Matthew 
has suggested below), Nicola Doebelin has integrated a "noise" cursor in 
his PROFEX software

https://profex.doebelin.org/
simply showing the +-sqrt(n)  bars.
If the noise of a pattern significantly deviates from this interval, 
something was going wrong, either in instrumental data 
collection/pretreatment or during export or conversion. No big science, 
but very helpful to identify bad or manipulated data.


Reinhard


Am 27/09/2019 um 08:15 schrieb Matthew Rowles:

Hi Tony

If you want to have a look at what the uncertainties are doing, then 
try scanning over a peak a couple of dozen times (maybe with a few 
different mA settings on the tube, maybe with some different step 
times) to collect a range of different intensities. The standard 
deviation of the "raw" counts (not raw CPS) should approximately the 
square root of the number of counts. If it is different, then 
something squirrelly is going on.


Matthew

On Fri, 27 Sep 2019 at 13:46, iangie > wrote:


Dear Rietvelders,

Thanks for your opinions!
The "re-binning" of 1D data was done by my measurement software
automatically, rather than by analysis software.
The CPS is unchanged after its "re-binning". This means, rather
than adding counts of neighboring steps, it is *averaging* my data
(sum counts up then divided by the number of combined bins)!
I have a feeling what my measurement software doing is not correct...

--
*Dr. Xiaodong (Tony) Wang*
*Research Infrastructure Specialist (XRD)*
Central Analytical Research Facility (CARF)   |   Institute for
Future Environments
Queensland University of Technology
*
*

在 2019-09-27 10:31:45，alancoe...@bigpond.com
 写道：

Hi Tony

>My I ask is this re-bined data from the measurement software considered as 
"raw data"
or "treated data"?

I’m not sure what is meant by treated data. Almost all neutron
data and synchrotron data with area detectors are “treated data”.

If the detector has a slit width in the equatorial plane that
is 0.03 degrees 2Th then it makes little sense using a step
size that is less than 0.03/2 degrees 2Th. If rebinning is
done correctly (see rebin_with_dx_of in the Technical
Reference) then rebinning is basically collecting redoing the
experiment with a wider slit.

In the case of your PSD then the resolution of the PSD would
be the smallest slit width. If the data has broad features
relative to the slit width then rebinning (or using a bigger
slit width) should not change the results. You could simulate
all this using TOPAS to see the difference. Correct rebinning
should not affect parameter errors.

This is a question that is not simple to answer and if there’s
concern then:

 1. Simulating data with the small step size and performing a fit
 2. And then rebinning with various slit widths and then fitting
 3. And then comparing parameters errors and parameter values
for all the refinements should shine light on the area.

I don’t know where but I feeling is that there should be
papers on this.

Cheers

Alan

*From:*rietveld_l-requ...@ill.fr
 mailto:rietveld_l-requ...@ill.fr>> *On Behalf Of *iangie
*Sent:* Thursday, September 26, 2019 1:40 PM
*To:* rietveld_l@ill.fr 
*Subject:* Software re-binned PD data

Dear Rietvelder,

I hope you are doing well.

It is generally acknolwdged that Rietveld refinement should be
performed on raw data, without any data processing.
One of our diffractometer/PSD  scans data at its minimal step
size (users can see that the step size during scan is much
smaller than what was set), and upon finishing, the
measurement software re-bin the counts to the step size what
users set (so the data also looks smoother, after re-bin).
My I ask is this re-bined data from the measurement software
considered as "raw data" or "treated data"? And can we apply
Rietveld refinement on this data?

Any comments are welcome. :)

--

*Dr. Xiaodong (Tony) Wang*

*Research Infrastructure Specialist (XRD)*

Central Analytical Research 

Announcement: Rietveld user meeting BGMN/Profex Freiberg September 16-18

[Reinhard Kleeberg]

*First Circular*

*User meeting “Rietveld analysis with BGMN/Profex”*

Kindly supported by TU Bergakademie Freiberg, RMS Foundation Bettlach, 
and the German- Swiss-Austrian Clay Group DTTG


 This workshop is addressed at persons using the BGMN Rietveld program 
in research, education, and industry. Basic knowledge in X-ray powder 
diffraction is assumed. The content focuses on the use of laboratory 
powder diffractometers and the application of BGMN/Profex in phase 
analysis. Examples in the tutorials are mainly from minerals and 
bioceramics.


Computer exercises will be performed on the participants’ own laptop 
computers. The BGMN and Profex software are under GNU GPL and will be 
distributed for free. Versions for Windows and Mac OS X systems will be 
available*. Copies of the presentations will be distributed as PDF 
files. Participation is limited to 20 persons and will be decided by the 
organizers on a first-come-first-served basis. Individual confirmation 
will be sent after the pre-registration deadline.* Versions for Linux 
will be available upon request


*Content:*-Introduction to BGMN and Profex

-Basic and advanced applications

-Focus session: Clay mineralogy

-Focus session: Quality management in MedTech

-Tutorials

*Lecturers:*Nicola Döbelin (Bettlach), Reinhard Kleeberg (Freiberg)

*Date:*September 16-18, 2019

*Place:*TU Bergakademie Freiberg, Department of Mineralogy

Brennhausgasse 14

D-09596 Freiberg Germany

*Fees:*includes workshop material and workshop dinner

full registration200,- €

student reduced100,- €

*Accommodation:*

Participants are kindly requested to organize their own accommodation, 
e.g. via Freiberg tourist servicehttp://www.freiberg-service.de/en.html


*Pre-registration:*

deadlineJuly 26^th 2019

by email to the address below, with name, institution, student/no, 
preferred focus session


*Contact:*Dr. Reinhard Kleeberg

Tel. 0049(0)3731 393244

Fax. 0049(0)3731 393129

Email kleeb...@mineral.tu-freiberg.de 
<mailto:kleeb...@mineral.tu-freiberg.de>



*Program*

*Monday, September 16*

**-Physical basics of XRPD related to laboratory instruments

-The Rietveld method, BGMN software and Profex GUI

-New features in Profex 4

oPhase identification (“search-match”)

oInteraction with 3^rd -party software (Match!, QualX, Vesta)

oElectron density maps

*Tuesday, September 17*

-Profile modeling (instrumental and sample related part)

-Preparation of crystal structure models

-Use of the BGMN interpreter language

-Tutorials

*Wednesday, September 18*

Parallel focus sessions

**-Focus Session “Clay Mineralogy”

oProblems related to clay mineral analysis

oTutorials

-Focus Session “Quality Management in MedTech”

oPerformance qualification of laboratory diffractometers

oValidation of XRD analysis according to ISO 13779-3:2018

oTutorials

*Tutorials*

-Settings and alignment of laboratory XRPD instruments

-Computer exercises on prepared problems (different levels)

-Instrument qualification and method validation


--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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Fwd: [Clay-talk] Reynolds Cup 2018 registration REMINDER

[Reinhard Kleeberg]

Dear colleagues,
sorry for multiple posting. Please find below the reminder for 
registration to the 9th Reynolds Cup in mineral phase analysis.

Best regards

Reinhard Kleeberg


 Weitergeleitete Nachricht 
Betreff:[Clay-talk] Reynolds Cup 2018 registration REMINDER
Datum:  Tue, 9 Jan 2018 10:32:32 +0100
Von:Rieko Adriaens <radria...@qmineral.com>
An: clay-t...@minlists.org, msa-t...@minlists.org



Dear colleagues,

The 9th biennial Reynolds Cup competition for quantitative mineral 
analysis is now open. Please register your participation _as soon as 
possible_ by sending an email to Rieko Adriaens radria...@qmineral.com 
<mailto:radria...@qmineral.com>. The competition is open to anyone 
interested in quantitative mineral analysis, with particular emphasis on 
clay mineralogy. Information about the competition including guidelines 
and previous winners can be found at http://clays.org/Reynolds.html . 
The competition is free for all to enter, however, those that are not 
members of the CMS are encouraged (but not obliged) to become members 
(see http://clays.org/join_benefits_of_membership.html).


Please use the following format when registering:

*Subject:*Please put "*Reynolds Cup 2018 registration*" in the subject 
line in your email request. In the body of the email please put the 
following information:


*Name: *

*Institution/organization:*

*Shipping address:*(that works for DHL/Courier delivery, e.g. physical 
address not Postal Box)


*Phone number*(for delivery)*:*

*Email address:*

We look forward to your participation! It is expected that the samples 
will be shipped *_on January 22^nd _ *.


Sincerely,

Rieko Adriaens

Gilles Mertens

Reynolds Cup 2018 organizers



University of 
Leuven 
Qmineral Analysis & Consulting


Celestijnenlaan 200 
E    
Gaston Geenslaan 1


3001 Heverlee 
(BELGIUM)  
 3001 Heverlee (BELGIUM)


www.ees.kuleuven.be/geology 
<http://www.ees.kuleuven.be/geology>www.qmineral.com 
<http://www.qmineral.com>


Tel. +32 16 32 64 
42  
Tel. +32 16 75 13 77


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++

Fwd: FW: Reynolds Cup 2018 registration is now open

[Reinhard Kleeberg]

*From:* Rieko Adriaens [mailto:radria...@qmineral.com]
*Sent:* Tuesday, December 12, 2017 12:01 PM

Dear colleagues,

The 9th biennial Reynolds Cup competition for quantitative mineral 
analysis is now open. You can register your interest in participating in 
the contest by sending an email to Rieko Adriaens radria...@qmineral.com 
. The competition is open to anyone 
interested in quantitative mineral analysis, with particular emphasis on 
clay mineralogy. Information about the competition including guidelines 
and previous winners can be found at http://clays.org/Reynolds.html. The 
competition is free for all to enter, however, those that are not 
members of the CMS are encouraged (but not obliged) to become members 
(see http://clays.org/join_benefits_of_membership.html).


Please use the following format when registering:

*Subject:*Please put "*Reynolds Cup 2018 registration*" in the subject 
line in your email request. In the body of the email please put the 
following information:


*Name: *

*Institution/organization:*

*Shipping address:*(that works for DHL/Courier delivery, e.g. physical 
address not Postal Box)


*Phone number*(for delivery)*:*

*Email address:*

A total of approximately 90 sets of samples will be available for 
distribution. Each set comprises three samples of approximately 3-4 g 
with mineral mixtures commonly found in clay bearing rocks. All sets of 
samples will be distributed in the order of registration. Samples are 
expected to be shipped at the latest at January 22nd 2018 with the 
deadline for submission of results by April 16th 2018. The top three 
contestants with the most accurate results will be announced at the 55th 
Annual Meeting of the Clay 
Minerals Society (June 11-14, 2018, Urbana-Champaign, Illinois).  Only 
the names of the top three contestants will be published. The names of 
the other participants will remain strictly confidential.


Because of the popularity of the Reynolds Cup and the enormous amount of 
work put into its preparation, potential participants are strongly 
encouraged to plan ahead and only request samples if they are sure they 
can complete the analysis and return results to the organizers by the 
due date. Those who request samples and do not send in results or fail 
to return the samples unopened WELL BEFORE the due date will not be 
eligible to participate in future Reynolds Cups. A waiting list will be 
kept to offer returned samples to other potential participants.


To ensure an even wider exposure, we encourage you to forward this 
announcement to your national mailing lists and mineralogy associations, 
colleagues and friends who might be interested in participating.


We look forward to your participation!

Sincerely,

Rieko Adriaens

Gilles Mertens

Reynolds Cup 2018 organizers



University of 
Leuven 
Qmineral Analysis & Consulting


Celestijnenlaan 200 
E    
Gaston Geenslaan 1


3001 Heverlee 
(BELGIUM)  
 3001 Heverlee (BELGIUM)


www.ees.kuleuven.be/geology 
www.qmineral.com 



Tel. +32 16 32 64 
42  
Tel. +32 16 75 13 77


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Re: An additional criterion for the Rietveld method

[Reinhard Kleeberg]

Dear Masami Tsubota,
thanks for pointing to the paper. To be honest I'm not completely clear 
about the meaning of some termini used in the summary, and about the 
value of this new criterion. My questions:


1) What does "peak shift" really mean in this context? Obviously you 
discuss any difference between a "measured" or "refined" angular peak 
position and the theoretical Bragg angle calculated from referenced or 
refined lattice parameters, plotted in fig. 1. Ok, the reference Bragg 
position is clear. It is also known (since Klug & Alexander, Wilson etc. 
in the 1950ies) that numerous geometrical effects complicate the peak 
shape, apparently "shift" the peak maximum from its theoretical value, 
and that these effects are strongly angular dependent (Jenkins, 
Schreiner in the 1980ies, textbooks...). Btw this is how the trends in 
fig 1 and 3 look like. Of course, if not taken into account correctly, 
these effects will bias the lattice parameters systematically. 
Basically, the primary question is how accurate we can 
model/calculate/correct all these effects in our Rietveld refinement 
procedure.
Let us assume that our peak shape model (no matter if in Rietveld, 
LeBail or local unconstrained profile fitting) includes these well-known 
geometrical aberrations of the maximum positions by any "fundamental 
parameter" or "ray tracing" approach, and the wavelength profile used in 
the convolution fits to the instrument correctly. Such approach includes 
besides the asymmetry also the instrumental/geometrical aberrations of 
the angular peak position, but of course not the unknowns related to the 
individual sample preparation (transparency Ts) and the individual 
instruments alignment (zero point Z and sample displacement Ds). As I 
understood, the latter 3 unknowns are included/refined in the model in 
this paper too (equation 1) and should be well refineable in all 
Rietveld programs when the pattern is good and measured up to high 
2theta. So, what additional kind of "peak shifts" else are discussed 
her? Or, do you rely only on the systematic, geometrically caused 
deviations of peak maximum positions when fitted "traditionally" (by 
analytical functions) in your Rietveld program? If yes, is your 
criterion maybe obsolete in refinements applying good FPA models?


2) What does "reproducibility of the peak shift" mean? How good a peak 
position (or shift from the reference value) can be reproduced by 
repetition of the measurement (including preparation), as I would expect 
from the usual meaning of the word "reproducibility" in analytical work? 
Or do you simply mean "how good your refinement model can fit the peak 
positions of the measured pattern"? If you mean the latter, we are back 
to the discussion above that an incorrect (or oversimplified) peak shape 
model in a Rietveld analysis may bias the refined lattice parameters. In 
my understanding, such kind of bias is a systematic error, simply caused 
by an incorrect model, and the term "reproducibility" sounds a bit 
misleading in this context.


3) It is clear that systematically wrong (fixed) lattice parameters will 
enhance the number of the proposed criterion (fig. 2 e,f). But what will 
happen in a practical refinement when the angular range is smaller, Z, 
Ts and Ds become more correlated, and maybe additional nonsense profile 
parameters are started to refine and compensate each other, e.g. for 
more broadened peak profiles? Will the values of this criterion still 
give a clear indication of any systematic error, or will they maybe 
masked by such correlation effects?


A few cents from a personal view: Of course I agree that the observation 
of any systematic misfit in the peak positions in Rietveld refinement is 
a valuable information, e.g. for identification of instrumental 
misalignment, or pointing to erroneous peak profile description in a FPA 
model. However, to get reliable lattice parameters in Rietveld 
refinement with a FPA model it is a recommended strategy to admix 
silicon SRM640c to a powder sample, fix the lattice parameters of this 
internal standard to the theoretical value during the refinement, and 
refine/adjust for example sample transparency parameters (a typical 
unknown in practice) in the peak profile model, until the profile and 
the peak position of the standard peaks are well fitted. So we can 
"anchor" the correlated angular effects by the standard peaks. But this 
is possible to do without this new criterion, so I'm not convinced of 
the necessity of the criterion proposed, at the moment.


Best regards

Reinhard



Am 14/11/2017 um 16:55 schrieb Johannes Birkenstock:


Dear Masami Tsubota,

thanks for directing us to your interesting, free access article. 
However, it is not stated in the article whether and how the new 
criterion could be applied in usual Rietveld refinements of 
non-certified samples.


Am I right that your new criterion (Σ|Δ2θR|(sum or all) = Min) relies 
on the previous knowledge of 

Re: Data collection strategy from low angles - Bruker D8 Advance, Lynx Eye XE detector

[Reinhard Kleeberg]

Dear Frantisek,
the best way to measure a clean diffraction pattern for clay mineral 
analysis is of course to avoid beam overflow, either by choosing a 
bigger sample length or a smaller fixed (or automatic) divergence slit.
However, if you are using the ADS (what should make sure that you 
primary beam bundle hits the sample only) and you have still a "positive 
effect of the knife edge" on background slope at angles below 7 deg, 
this is simply a message that your primary beam bundle isn't "clean"! If 
this "knife edge" really keeps away any kind of radiation from the 
detector, you can simply calculate (or draw) the connection from the 
detector channel at this angle over the knife edge position (2.5 mm 
above the sample) towards the "source" of your unwanted background. The 
line ends about 6-8 mm below the beam center, in front of the tube 
window. This radiation is neither from the sample nor any "air scatter", 
but simply from the material region around the lower edge of the tube 
housing or the shutter opening. This area is hit by the intense primary 
bundle (before the divergence slit) and becomes a source of 
fluorescence/scatter. From here this radiation can pass the divergence 
slit inclined and above the sample, and so it reaches the detector. In 
fact, if there would be a second slit position close to the tube shutter 
(as it was constructed in older instruments), this unwanted radiation 
could be blocked effectively before reaching the ADS. We tried this by 
inserting some tungsten or steel blades glued in the filter frame of the 
Panalytical Empyrean instrument, and it works very well, without cutting 
the beam bundle at higher angles as the fixed knife edge does. And this 
solution is much cheaper than a "motorized knife edge" ;-)

Best regards

Reinhard

Am 22/10/2016 um 06:46 schrieb iangie:

Dear Frantisek,

>I have tried the 0.26 and 0.14° FDS, however a large "beam overflow" 
has occurred. Moreover, the intensities of diffractions at higher 
angles are very low in comparison to the data collected with ADS slits.
[TW] At θ=1° , 0.26 and 0.14° FDS coresponding to ~39 and ~74 mm 
footprint on sample, respectively, which is much longer than your 
sample length 15mm. This beam overspill will induce air 
scattering which increases background at that angle.
Using ADS, the sample volume illuminated is increasing with Sinθ 
dependance, therefore you observe "higher" peak intensity at high angle.
At 2θ=2°, the knife edge hieght should be lower; At 2θ=50°, the knife 
edge height should be higher. Therefore, I recommanded you use 
Bruker's Motorised Knife Edge, which retracts itself in real time 
accoding to beam divergence and # of detector openning channels 
at each θ.
Your LynxEye XE PSD should be able to opearte in Variable Detector 
Openning mode, which opens fewer channels at low angle and all 
channels at higher angle. You may want to try the scan type: "Coupled 
2Theta/Theta (VDO)".
However, the ultimate solution would be combining ADS, MKE, VDO 
together, which gives lowest possible background at low angle, ideal 
for recording clay basal reflections.


--
Yours Sincerely,
Dr. Tony Wang

At 2016-10-21 21:59:23, "František Laufek" 
 wrote:


Dear all,

I would like to ask you about your experience in collecting the
XRD data from low angles (for me from 2° of 2Theta) to 50° 2Theta
using the Bruker D8 Advance diffractometer

(Bragg-Brentano geometry) with the Lynx Eye XE position sensitive
detector.

The studied samples are clay minerals and the main purpose of the
task is qualitative and later (semi)quantitative phase analysis.

I have fixed beam knife (=Anti-Scatter Screen) and ADS/FDS slits,
280 mm is the goniometer radius. The length of my samples is
around 15 mm.

After a few experiments and calculation, the optimal data
collection strategy seems to be:

- 10 mm automatic divergence slits (ADS), beam knife 2.5 mm above
the sample (beam knife at this position does not interfere with
the primary beam (to 50°) and still reduces the background at low
angles).

I have tried the 0.26 and 0.14° FDS, however a large "beam
overflow" has occurred. Moreover, the intensities of diffractions
at higher angles are very low in comparison to the data collected
with ADS slits.


Any suggestions are welcome.



Frantisek Laufek

Czech Geological Survey

Prague

Czech Republic






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--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244

Re: Parafocussing definition?

[Reinhard Kleeberg]

Dear Tony,

Am 03/05/2016 um 12:58 schrieb Tony Raftery:


What the world needs is better control of antiscatter.  Mis-set 
anti-scatter or absent anti-scatter slits make life a misery if one 
has any intention of modelling a diffraction pattern.


exactly. This holds not only for mysterious "bumps" coming from plastic 
sample holders what should not be hit by the primary bundle, but also 
for strange "edges" at low angles, even if theta-compensating divergence 
slits are in use.


I have great hopes for automatic knife edges but I can see the great 
scope for it all going dreadfully wrong. I have yet to see any model 
for how such a thing should work (as in how far the slit should be 
above the sample as a function of diffractometer radius or divergence 
slit width). Manual knife edges are great (properly aligned at about 
10um tolerance in height, and about 0.1 deg in chi [that’s hard to 
do]) – but then only useful for a restricted (to very restricted) 
2theta range  otherwise “asymmetrically limiting the 
incident/diffracted beam bundle“.


A simple drawing of the beam path shows the origin of the "scattered" 
radiation what can be reduced by the "knife edge": The "background edge" 
in our patterns was at approximately 7 deg 2theta, even if an 
theta-compensating divergence slit and a 0d-detector was used! 
Connecting the 7 deg detector position and the "knife edge" position 
(what really shifts this edge toward lower angles when going down) 
clearly hits a position at the tube housing approximately 3-4 mm below 
the beam center, i.e. the lower side of the borehole in the shutter 
opening. This is the source of fluorescence radiation (Cu, Zn if brass 
is the material), passing through the divergence slit above the sample, 
and hitting i) at lower angles directly the detector or ii) at higher 
angles the right side of the sample holder. This can be effectively 
removed by a second "anti-scatter" slit immediately in front of the tube 
window: This slit must just be significantly smaller than the opening in 
the tube housing. In fact, all our old instruments have such a second 
slit position, no problem. A newer machine (no brand names) has there at 
least a filter frame. We glued parallel strips (distance 2.4 mm)  of 
tantalum (by tape) on the filter frame, and the problem was solved, 
clean background down to 3 deg 2theta, the knife edge could be removed 
completely.
The take home message: A clean primary beam bundle just hitting the 
sample helps a lot, and in the 1970ies this fact was still known to the 
manufacturers ;-)
But of course programmable knife edge works as well and is a better 
business for the company ;-)


Reinhard

I have great hopes for automatic variable divergence slits also – just 
do or don’t think of the anti-scatter issues (as in requires a 
programmable a-scatter on both the incident and diffracted beam side 
[diffracted side is the problem as it depends on detector parameters 
for a 1D detector]) .


regards,

Tony Raftery

*Tony Raftery*  | Projects Manager – X-ray & Particles Laboratory
Central Analytical Research Facility (CARF)  |  Queensland University 
of Technology (QUT)


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*From:*rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] 
*On Behalf Of *Reinhard Kleeberg

*Sent:* Tuesday, 3 May 2016 7:18 PM
*To:* Matthew Rowles <rowle...@gmail.com>
*Cc:* rietveld_l@ill.fr
*Subject:* Re: Parafocussing definition?

Am 03/05/2016 um 03:00 schrieb Matthew Rowles:

K (and also Brentano, upon rereading) say that in order to be
focussing, the sample also needs to be toroidally curved; curved
along ACB as well as be rotated about the axis AB; so it is a
little more than the traditional flat-sample effect

Yes. And as ACB is not constant, a "focusing sample" should change 
their curvature (bent radius) following the focusing circle versus 
2theta,  getting more bent with higher diffraction angle, what is hard 
to do... That's why Bragg-Brentano geometry (flat sample) is the 
working compromise.


Btw, understanding the geometric principles seems to be a bit out of 
fashion, as we nowadays can find "strange" instrumental configurations 
for common powder diffraction work in many laboratories, for example:
- parallel primary beam optics in combination with narrow po

Re: Parafocussing definition?

[Reinhard Kleeberg]

Am 03/05/2016 um 03:00 schrieb Matthew Rowles:
K (and also Brentano, upon rereading) say that in order to be 
focussing, the sample also needs to be toroidally curved; curved along 
ACB as well as be rotated about the axis AB; so it is a little more 
than the traditional flat-sample effect


Yes. And as ACB is not constant, a "focusing sample" should change their 
curvature (bent radius) following the focusing circle versus 2theta,  
getting more bent with higher diffraction angle, what is hard to do... 
That's why Bragg-Brentano geometry (flat sample) is the working compromise.


Btw, understanding the geometric principles seems to be a bit out of 
fashion, as we nowadays can find "strange" instrumental configurations 
for common powder diffraction work in many laboratories, for example:

- parallel primary beam optics in combination with narrow point detectors,
- overmuch long linear detectors combined with a Bragg-Brentano setup,
- small "antiscatter" slits in front of big linear detectors,
- "knife edge" antiscatter slits above the sample, asymmetrically 
limiting the incident/diffracted beam bundle,

etc. pp

Reinhard




So summarising everyone here, and the papers I've been reading, 
parafocussing means "sort of focussing given the constraints of 
actually making a physical diffractometer". Also, we have a finite 
source and detector size, and that with the dimensions of beam 
footprint and goniometer radii that we use mean that it all pretty 
much works out in the end.



Matthew

On 2 May 2016 at 20:07, Kern, Arnt > wrote:


Matthew,

I think Klug & Alexander (1974) give a good explanation about the
origin of the term "parafocusing": 2nd edition, section
"parafocusing methods", page 222 ff.

Cheers,

Arnt

*From:*rietveld_l-requ...@ill.fr

[mailto:rietveld_l-requ...@ill.fr
] *On Behalf Of *Eduard E. Levin
*Sent:* Montag, 2. Mai 2016 13:21
*To:* Cline, James Dr. (Fed); Matthew Rowles
*Cc:* rietveld_l@ill.fr 
*Subject:* RE: Parafocussing definition?

Dear James,

For me too, please, if it would not be much of a trouble.
Thank you in advance!

Eduard

*On Mon, 2 May 2016 11:09:31 +, Cline, James Dr. (Fed) wrote*
> Bob Cheary and I developed and presented a workshop several
times in the 1990's that included a discussion of this issue.  I
can send you the notes for it if you would like them.
>
> Jim
>
>
> James P. Cline
> Materials Measurement Science Division
> National Institute of Standards and Technology
> 100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ]
> Gaithersburg, MD 20899-8523USA
> jcl...@nist.gov 
> (301) 975 5793 
> FAX (301) 975 5334 
>
> *From:* rietveld_l-requ...@ill.fr

[mailto:rietveld_l-requ...@ill.fr
] *On Behalf Of *Matthew Rowles
> *Sent:* Monday, May 02, 2016 1:53 AM
> *To:* RIETVELD_L Distribution List >
> *Subject:* Parafocussing definition?
>
>
> Hi all
>
>
>
> I've been trying to find a good explanation of what
parafocussing (wrt Bragg-Brentato geometry) actually is, but
haven't been able to find one.
>
>
>
> Klug and Alexander just reference Brentano's papers.
>
>
>
> "The Basics of Crystallography and Diffraction" 2nd ed say that
B-B geometry is "semi-focussing" because the sample is flat, and
not curved to follow the focussing circle (this doesn't sound
right to me)
>
>
>
> Brentano, J Appl. Phys. 17, 420 (1946) says that a ray
reflecting off the arc defined by ACB where A is the source, C is
the centre of the gonio, and B is the detector (ie the focussing
circle)  is automatically parafocussing, because you only can
establish the location of the crystallites, not their orientation,
but then goes on to say that you can actually find the
orientation, as the lattice plane normal bisects the angle ACB.
>
>
>
> I also haven't been able to find a use of the word "parafocus"
outside of the diffraction literature, so I can't see how the word
is used elsewhere.
>
>
>
> Any ideas?
>
>
>
>
>
> Matthew


-- 
Open WebMail Project (http://openwebmail.org

)




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Reynolds Cup 2016 registration closed

[Reinhard Kleeberg]

Sorry for multiple posting:
The registration for the 8th biennial Reynolds Cup competition in 
mineral analysis is closed now, the samples are dispatched. The total 
number of registrations is 81.

To all participants: Good luck and have fun!

Reinhard Kleeberg

--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Reminder: Reynolds Cup 2016 registration opened, start January 22nd

[Reinhard Kleeberg]

Sorry for multiple posting: Just a reminder that the starting point of 
the 8th biennial RC is approximating.

We plan to ship the samples *Friday, January 22nd.*
There are still samples available, so the registration will be possible 
until Thursday, January 21st.


Best regards

Reinhard Kleeberg
RC 2016 organizer

--

Dear colleagues,
the 8th biennial Reynolds Cup competition for quantitative mineral analysis
is now open. You can register your interest in participating the contest by 
sending an
email to Reinhard Kleeberg<kleeb...@mineral.tu-freiberg.de>. Information about 
the competition including guidelines and previous winners can be found at
http://www.clays.org/SOCIETY%20AWARDS/RCintro.html. The competition is free
for all to enter, however, those that are not members of the CMS are
encouraged (but not obliged) to become members (see
http://www.clays.org/MEMBERSHIP/MemberRates.html  for details).
 
Please use the following format when registering:


Subject: Please put "Reynolds Cup 2016 registration" in the subject line in
your email request.

In the body of the email please put the following information:
Name:
Institution/organization:
Shipping address: (that works for DHL/Courier delivery, e.g. physical
address not Postal Box)
Phone number (for delivery):
Email address:
 
A total of approximately 90 sets of samples will be available for

distribution. Each set comprises three samples of approximately 4 g with
mineral mixtures commonly found in clay bearing rocks. All sets of
samples will be distributed in the order of registration. Samples are
expected to be shipped at January 22nd 2016 with the deadline for
submission of results by April 8th 2016. The top three contestants with
the most accurate results will be announced at the53rd Annual meeting 
<http://conferences.illinois.edu/CMS2016/index.html>
of the Clay Minerals Society (June 5-8, 2016, Atlanta, Georgia.
Only the names of the top three contestants will be published. The names of the 
other participants will remain strictly confidential.
 
The competition is open to anyone interested in quantitative mineral

analysis, with particular emphasis on clay mineralogy.
 
Because of the popularity of the Reynolds Cup and the enormous amount of

work put into its preparation, potential participants are strongly
encouraged to plan ahead and only request samples if they are sure they can
complete the analysis and return results to the organizers by the due date.
Those who request samples and do not send in results or fail to return the
samples unopened WELL BEFORE the due date will not be eligible to
participate in future Reynolds Cups.

A waiting list will be kept to offer returned samples to other potential
participants.
 
To ensure an even wider exposure, we encourage you to forward this

announcement to your national mailing lists and mineralogy associations,
colleagues and friends who might be interested in participating.
 
We look forward to your participation!


Sincerely,

Reinhard Kleeberg
Reynolds Cup 2016 organizer


--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Reynolds Cup 2016 registration opened

[Reinhard Kleeberg]

Dear colleagues,
the 8th biennial Reynolds Cup competition for quantitative mineral analysis
is now open. You can register your interest in participating the contest by 
sending an
email to Reinhard Kleeberg<kleeb...@mineral.tu-freiberg.de>. Information about 
the competition including guidelines and previous winners can be found at
http://www.clays.org/SOCIETY%20AWARDS/RCintro.html. The competition is free
for all to enter, however, those that are not members of the CMS are
encouraged (but not obliged) to become members (see
http://www.clays.org/MEMBERSHIP/MemberRates.html  for details).
 
Please use the following format when registering:


Subject: Please put "Reynolds Cup 2016 registration" in the subject line in
your email request.

In the body of the email please put the following information:
Name:
Institution/organization:
Shipping address: (that works for DHL/Courier delivery, e.g. physical
address not Postal Box)
Phone number (for delivery):
Email address:
 
A total of approximately 90 sets of samples will be available for

distribution. Each set comprises three samples of approximately 4 g with
mineral mixtures commonly found in clay bearing rocks. All sets of
samples will be distributed in the order of registration. Samples are
expected to be shipped at January 22nd 2016 with the deadline for
submission of results by April 8th 2016. The top three contestants with
the most accurate results will be announced at the53rd Annual meeting 
<http://conferences.illinois.edu/CMS2016/index.html>
of the Clay Minerals Society (June 5-8, 2016, Atlanta, Georgia.
Only the names of the top three contestants will be published. The names of the 
other participants will remain strictly confidential.
 
The competition is open to anyone interested in quantitative mineral

analysis, with particular emphasis on clay mineralogy.
 
Because of the popularity of the Reynolds Cup and the enormous amount of

work put into its preparation, potential participants are strongly
encouraged to plan ahead and only request samples if they are sure they can
complete the analysis and return results to the organizers by the due date.
Those who request samples and do not send in results or fail to return the
samples unopened WELL BEFORE the due date will not be eligible to
participate in future Reynolds Cups.

A waiting list will be kept to offer returned samples to other potential
participants.
 
To ensure an even wider exposure, we encourage you to forward this

announcement to your national mailing lists and mineralogy associations,
colleagues and friends who might be interested in participating.
 
We look forward to your participation!


Sincerely,

Reinhard Kleeberg
Reynolds Cup 2016 organizer

--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Announcement workshop BGMN/Profex focused on phase analysis

[Reinhard Kleeberg]

*First Circular*

*User meeting “Rietveld analysis with BGMN”*

Kindly supported by the TU Bergakademie Freiberg, RMS Foundation 
Bettlach, and the German- Swiss-Austrian Clay Group DTTG


This workshop is addressed at persons using the BGMN Rietveld program in 
research and education. Basic knowledge in X-ray powder diffraction is 
assumed. The content focuses on the use of laboratory powder 
diffractometers and the application of BGMN in phase analysis. Examples 
in the tutorials are mainly from minerals and rocks.


Computer exercises will be performed on the participants’ own laptop 
computers. The BGMN and Profex software are under GNU GPL and will be 
distributed for free. Versions for Windows and Mac OS X systems will be 
available. Copies of the presentations will be distributed as PDF files. 
Participation is limited to 20 persons and will be decided by the 
organizers on a first-come-first-served basis. Individual confirmation 
will be sent after the pre-registration deadline.


*Content:*2 * 6 hours in total

Lectures:- physical basics of XRPD related to laboratory instruments

- the Rietveld method and BGMN software

- use of the GUI Profex (Nicola Döbelin)

- profile modeling

- problems related to quantitative phase analysis

Tutorials:- settings of laboratory XRPD instruments

- simulation and checking of instrumental profiles

- computer exercises on prepared problems

- use of control files for phase quantification

- sources of errors in mineral quantification

*Lecturers:*Reinhard Kleeberg (Freiberg), Nicola Döbelin (Bettlach, Bern)

**

*Date:*March 1-2 2016

*Place:*TU Bergakademie Freiberg, Department of Mineralogy

Brennhausgasse 14

D-09596FreibergGermany

*Fees:*includes workshop material and workshop dinner

full registration180,- €

student reduced80,- €

*Accommodation:*

Participants are kindly requested to organise their own accommodation, 
e.g. via Freiberg tourist 
servicehttp://www.klick-auf-freiberg.de/engl/index.htm


*Pre-registration:*

deadlineJanuary 24^th 2016

by email to the address below, with name, institution, student/no

*Contact:*Dr. Reinhard Kleeberg

Tel. 0049(0)3731 393244

Fax. 0049(0)3731 393129

Email kleeb...@mineral.tu-freiberg.de 
<mailto:kleeb...@mineral.tu-freiberg.de>


--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Re: Powder Diffraction Discussion Group on Facebook

[Reinhard Kleeberg]

To be honest, I can't imagine that crystallographic knowledge can be 
effectively transmitted via facebook. Probably one could safe time by 
reading some basic textbooks instead of liking and following. The 
same holds for other asocial (Lubo, I like this statement!) networks 
like researchgate, what also waste the time even of uninvolved people by 
spamming, just for generating profits by the companies.


The central points have already been fixed by Alan:

The advantage of the Rietveld mailing list is that contributions
aren't anonymous, it is not commercial and no use is made of users'
information, publicity is limited, and there is a structured archive
of discussion that is open to all, even those who don't have an account.

This is like science should be. Alan, thank you very much for all your 
altruistic efforts with the list!

Greetings

Reinhard



Am 08/06/2015 um 14:00 schrieb Davide Levy:

I want say something more about my decision to open the group in FB.
There is many people the use the Rietveld method as a magic black box:
insert the data, read the cif of the phase and obtain the results. Then they
say twenty-one and forty-one when they see a symmetry group!
Maybe a POP-group in FB can teach more about crystallography to a larger
group of scientist!
this is my opinion.
Davide

-Original Message-
From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf
Of Lubomir Smrcok
Sent: 08 June, 2015 2:49 PM
To: Alan Hewat
Cc: rietveld_l@ill.fr
Subject: Re: Powder Diffraction Discussion Group on Facebook

Dear Alan,

There are plenty of people who call usage of so-called social networks (they
are, in fact, very asocial) a progress. I would suggest to consider De
gustibus non est disputandum, but also Duo cum faciunt idem, non est idem.

Although I am not member of any of those asocial nets and do not plan to be,
I sometimes think of the end of such services like Gopher. Maybe we have
around a generation, who prefers to share instead of to search, think 
write. What a prefect opportunity for commercial companies :-)

Best,
Lubo


On Mon, 8 Jun 2015, Alan Hewat wrote:


I can understand that people have different ideas about the ideal
format for discussion, and for some of us email may seem a little old
fashioned. I suppose we could also use Twitter or any of the other
social chattering forums. But multiple groups on the same subject
disperses the available information, and it would be good to have some
kind of consensus rather than individual initiatives.
The advantage of the Rietveld mailing list is that contributions
aren't anonymous, it is not commercial and no use is made of users'
information, publicity is limited, and there is a structured archive
of discussion that is open to all, even those who don't have an account.

I myself simply inherited the list, but think it worth maintaining,
and would discourage members from posting to multiple groups on the
same subject.

Alan. (What, me worry ? :-)

On 8 June 2015 at 09:24, davide levy davide.lev...@gmail.com wrote:

   Good Morning
   I created the Powder Diffraction Discussion Group on Facebook,
   to speak about powder diffraction, Rietveld etc..  open for all
   use powder diffraction.
   https://www.facebook.com/groups/1087352967946225/
   Davide


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--
__
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
alan.he...@neutronoptics.com +33.476.98.41.68
 http://www.NeutronOptics.com/hewat
__





--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

corundum internal standard alternative?

[Reinhard Kleeberg]

Dear colleagues,
does anybody know a fine-grained alumina (corundum) material with high 
purity, suitable for using as internal standard in quantitative phase 
analysis, as an economic alternative for the NIST SRM 676a?
In the past we used American Elements AL-OX-03-S (spray-dried) what 
worked quite well, but this is out of stock now and substituted by 
AL-OX-03M-PSP (plasma-sprayed). Are there any experiences with 
plasma-sprayed corundum products?

Thanks in advance

Reinhard

--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Re: Statistics on semi-quantitative XRD data

[Reinhard Kleeberg]

I don't think that the term semi-quantitative is defined sharp enough 
to provide a basis for a serious statistical evaluation. In geosciences 
typically semi-quantitative is attributed to data where an estimation 
of errors is missing,  that have been never cross-checked by an 
independent method, and so they are suspected to be biased by serious 
systematic errors. If so, than datasets originating from different 
sources cannot be treated seriously together in a statistical 
evaluation, per definition. In the best case, they can be used to 
compare samples of one series measured with the same instrument and 
analyzed by the same procedure. Unfortunately many authors report wt% 
even in semi-quantitative phase analysis, what suggests compatibility. 
This is misleading and should be avoided. For the statistical evaluation 
of a series of comparably measured diffraction patterns of one 
geological object it seems more serious to apply cluster analysis of the 
raw patterns or to use any intensity ratios. But of course the best way 
is to improve the evaluation method to be really quantitative, i.e. 
free of systematic error and evaluated by realistic e.s.d.'s.


Reinhard Kleeberg

Am 13/11/2014 18:53, schrieb James Talbot:

Hello All,

I had the following request from a client:

I am looking for examples of statistics used on semi-quantitative 
data, i.e. comparing XRD results of multiple samples.  Do you have any 
recommendations or know of any papers that clearly explain their 
statistical methods?  In so many papers, it is glossed over.  I have a 
pretty good handle on my stats, but would prefer to see what other 
have done with XRD datasets.


Can anyone help with this.?  I do not know of any of the top of my head.

Thanks in advance,
James Talbot


K-T GeoServices, Inc.
970-641-1235 (office)
940-597-9076 (mobile)
219 North Iowa Street, Unit J
Gunnison  CO  81230-2479
www.ktgeo.com



--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

workshop clay minerals characterization Karlsruhe, 9-13 Mar 2015

[Reinhard Kleeberg]

Dear colleagues,
the German-Swiss-Austrian Clay Group DTTG organizes a 5-day workshop on 
clay minerals characterization, including lectures and computer 
exercises on XRD and Rietveld phase analysis of samples containing clay 
minerals. The workshop may be useful to PhD students working on projects 
dealing with clay-bearing materials.


More information at:
http://www.dttg.ethz.ch/workshop2015.html
http://www.dttg.ethz.ch/workshop%202015%20Karlsruhe.pdf

Reinhard Kleeberg

--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Re: Reference Intensity Ratio of clay minerals

[Reinhard Kleeberg]

Dear Maria,
indeed the relative intensities of the first basal reflection (you 
expressed this as RIR) of smectites/vermiculites are quite high. There 
are several reasons:
1) because of high d spacings / low diffraction angle peaks always cause 
high L and P factors
2) because the layered structure with in-plane cations in the interlayer 
gives really high structure factors for 001
3) because the ideal structures of smectite presented in some papers 
do not take into account the positional disorder of the water molecules 
in the interlayer and therefore unrealistic intensities are calculated 
from such ideal structure models.


Moreover, you should take into account that the intensity of these first 
basal reflection is highly sensitive to variations in site (cation) 
occupation of octahedra and interlayer positions, the hydration stage, 
the uncertainties of z coordinates, and of course to experimental 
effects like preferred orientation, beam overflow, sample roughness... 
The peak profiles are often complicated by the slope of LP and by maybe 
inhomogeneous hydration stages...
Thus, any quantification of smectites/vermiculites based on the integral 
intensities of their first basal reflections is in general a dangerous 
undertaken (even if some frequently used techniques in soil and sediment 
research are based on this). See also Reynolds, R.C. (1989) in Pevear  
Mumpton (1989) and many other textbooks on clay mineral analysis.


Best regards

Reinhard

Am 02/04/2014 11:47, schrieb Leonid Solovyov:

The Rietveld-QPA doesn’t require RIR, as the peak intensities of phases are 
calculated from the structure models. What do you mean under “doing Rietveld” 
and ”structural files” in your case?

  
***

Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
660036, Akademgorodok 50/24, Krasnoyarsk, Russia
http://sites.google.com/site/solovyovleonid
***


- Original Message -
From: Chrysochoou, Maria mchry...@engr.uconn.edu
To: rietveld_l@ill.fr rietveld_l@ill.fr
Cc:
Sent: Wednesday, April 2, 2014 4:21 PM
Subject: Reference Intensity Ratio of clay minerals

Hello,

I am wondering why the RIR of clay minerals such as vermiculite and 
montmorillonite is so high in the structural files (e.g. around 22-28). I am 
not a crystallographer, but I have noticed that high RIRs are usually 
associated with dense structures and heavy elements and neither is the case 
with clays. And for example, kaolinite and illite have much lower RIRs, 1 and 
0.5, even though the structures are not that much different. This results in 
very very low concentrations when doing Rietveld, even though there is 
substantial intensity associated with vermiculite and it does not make 
intuitive sense to me.

I would appreciate any insight into this question.

Thank you,
Maria Chrysochoou
Associate Professor
Department of Civil and Environmental Engineering
University of Connecticut
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--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Re: PO corrections in trigonal space groups?

[Reinhard Kleeberg]

Dear Matthew,
in my knowledge, for calcite the {104} in the usual cell choice for 
hexagonal axes is equivalent to {10-11} in rhombohedral axes setting. 
Morphologically, this shape is called by mineralogists the main 
rhombohedra and the six faces belonging to {104} are indeed the 
directions of the perfect cleavage. Thus, the shape of calcite particles 
crushed/milled from bigger crystals are nearly perfect rhombohedra (btw 
a typical exercise used in undergraduate mineralogy classes for 
demonstrating cleavage).
In common powder sample preparation, you can expect preferred 
orientation of these planes parallel to the sample surface. For 
Bragg-Brentano geometry (rotational symmetric, observation direction 
perpendicular to the sample surface), you need any function fulfilling 
the symmetry of the Laue class for the description of the relative 
polar-axis density of the hkl oriented parallel to the sample surface. 
This is realized by symmetrized spherical harmonics as introduced by 
Järvinen et al. (1970), Popa (1992), Järvinen (1993, 1998). This and 
similar approaches are included in many Rietveld programs, e.g. GSAS, 
TOPAS, BGMN, MAUD, DDM (?)...


Back to calcite: You can see an example of a practically working 
correction function in fig. 1c of


Bergmann, J., Monecke, T., Kleeberg, R. (2001) Alternative algorithm for 
the correction of preferred orientation in Rietveld analysis. J. Appl. 
Cryst. 34, 16-19.


This function has maxima in the direction of the {104} normal vectors. 
As Leonid wrote, the description of such a rhombohedral symmetry is not 
possible by any uniaxial function like March-Dollase related to one 
special hkl. So there is no way around to choose a more complicated 
model than the March-Dollase.


However, keep in mind that all these models like spherical harmonics 
have no real physical meaning and are limited in their application. They 
can effectively describe the PO only for rotational symmetry of your 
diffraction experiment, only up to a certain (weak) degree of PO, and 
only if there is a homogeneous PO in your powder sample. So the 
application of any PO correction models in Rietveld analysis is a 
potential source of errors and just the second-best solution. The best 
is always an optimized preparation for a randomly oriented powder mount.


Reinhard

Am 26/03/2014 05:46, schrieb Leonid Solovyov:

Dear Mathew,

The 104 plane in calcite corresponds to the most intense reflection that is related, in turn, to the best 
spacing or separation between atomic layers along which the cleavage may 
occur. This is not a strict rule, of course, as real cleavage planes may be different depending on specific 
interatomic interactions in the crystal and other aspects, but it works in many cases.
Note also, that the 104 plane in the hexagonal setting has several 
symmetry-equivalents, while most Rietveld programs normally generate only one 
equivalent hkl for each diffraction peak, which makes the uniaxial 
March-Dollase PO correction invalid for such peculiar directions. This problem 
is resolved in DDM, where I included a special expanded-hkl option to generate 
all equivalent hkl's for every peak. About other programs I'm not sure.

Best regards,
Leonid
***
Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
660036, Akademgorodok 50/24, Krasnoyarsk, Russia
http://sites.google.com/site/solovyovleonid
***



From: Matthew Rowles rowle...@gmail.com
To: Sitepu, Husinsyah husinsyah.sit...@aramco.com
Cc: daniel.chateig...@ensicaen.fr daniel.chateig...@ensicaen.fr; 
rietveld_l@ill.fr rietveld_l@ill.fr
Sent: Wednesday, March 26, 2014 8:16 AM
Subject: Re: PO corrections in trigonal space groups?



Thanks for your replies.

Husin, is there any justification for the use of the 104 direction in calcite, 
other than this is the direction that works? I'm all for doing it if it works, 
but I'd like a little theoretical backup.

Thanks Daniel. I'll put something together for a look-see. What corrections are 
being used in Maud? Are there any papers on them?

THanks

Matthew



--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Re: Dollase Paper

[Reinhard Kleeberg]

Norberto,
if the magnetite crystals in a natural sample are so big that you can 
observe their octahedral morphology and this shape really gives rise to 
any significant PO, than they are also definitely too big for any 
quantitative XRPD phase analysis. Therefore, reducing the particle size 
is definitely necessary, simply to minimize the effects of microabsorption.
Milling of magnetite is no problem in any usual type of mills, e.g. 
McCrone micronizing mill, using agate, corundum, or zirconia grinding 
elements. Even hand-grinding in an agate mortar can be tried. As 
magnetite has no extreme tendency for cleavage, milled magnetite powder 
should not tend to PO in powder samples and no PO correction is necessary.


Reinhard


Am 21/03/2014 10:59, schrieb Norberto Masciocchi:

Dear Friends,

I am facing a problem in quantifying magnetite in a complex natural 
mixture, using the conventional Rietveld method (in its quantitative 
analysis approach). Apparently, the octahedral morphology of 
(difficult to grind) magnetite crystals affects itd diffraction pattern.


To my knowledge, as certified in the original paper (JAC 1986, 
267-272), the ubiquitous and highly performing March-Dollase equation, 
holding for any crystal symmetry, only applies to inequant 
crystallites (i.e. crystallites with unequal sides), or, better said, 
to effectively rod- or disk-shaped specimens (provided that the 
geometry of the experiments keeps cylindrical symmetry). Neither 
octahedral nor cubic (e.g., NaCl) crystals can be considered inequant.


So, the question is:
Is there any way do get around this problem (without resorting to 
spherical hamonics or to grind the specimen in a WC, SiC or BN mill)?


Thank you for your patience.

Norberto




--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

++
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++

Re: XRF and XRD best practice...

[Reinhard Kleeberg]

The basic question how useful chemical analysis can be for quantitative 
phase analysis of rocks is simply the ratio between the number of phases 
and the number of main elements contained, i.e. the complexity of the 
system. If you have rocks containing a big number of minerals maybe 
having variable or unknown chemical formulae, and the number of unknowns 
is bigger than the number of main elements, than the linear equation 
system is under-determined and you can just calculate ranges of possible 
mineralogical compositions. But of course in fortunate, simple cases it 
is possible to calculate the mineralogical composition directly from the 
XRF analysis.
In principle it is possible to add chemical constraints to a Rietveld 
refinement. However, in my experience the qualitative mineralogical 
analysis of rocks is a much bigger hurdle, and the typical uncertainties 
in qualitative mineralogical analysis and the uncertainties of average 
mineral formulae in complex rocks prohibit an effective use of this tool 
for QPA.

Best regards

Reinhard

Am 14/02/2014 22:21, schrieb Łukasz Kruszewski:

Hi. I think XRF can help only in case of simple samples or, e.g., to
disclude some strange elements, by proving there's none of them in the
particular sample. But when you have, lets say, a mixture containing a
spinel and periclase (MgO), then you won't be able to confirm by XRF
itself that all the Mg determined is cointained in periclase only, as
spinels take Mg too. An EDS or WDS system would be better here, but of
course it gives reasonable results for thin sections mostly. However, even
tiny 3D chunks of a sample can be used to confirm the presence of the
particular species you've included in the QPA refinement.

Good luck!

Luke Kruszewski



Hello all,

I use Rietveld primarily for quantitative phase analysis of rock samples.
We collect XRF and XRD data on our samples.

Is there a best practice for using these data together? Or a recognized
method or procedure for evaluating the agreement between the two? Can the
XRF be used to restrain the phase concentrations in a refinement?

Thank you all for the years of advice I have gotten from this forum.

All the best,
Blaise







--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

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++

Announcement BGMN user meeting Freiberg, March 12-13, 2014

[Reinhard Kleeberg]

Dear colleagues,
please find below some information regarding a user meeting on the 
application of the BGMN Rietveld software to be held in Freiberg, 
Germany, March 12-13, 2014.

With best wishes for a Happy Christmas

Reinhard Kleeberg

*
*

*Rietveld analysis with BGMN*

**

The workshop is addressed to persons using the BGMN Rietveld program in 
research and education. Basic knowledge in X-ray powder diffraction is 
assumed. The content focuses on laboratory powder diffractometers, the 
application of BGMN in phase analysis, and examples in the tutorials are 
mainly from minerals and rocks, inclusive clay materials.


Computer exercises will be performed on the participants own laptop 
computers. The BGMN, BGMNwin and Profex software are under GNU GPL and 
will be distributed for free. Versions for Windows and Linux systems 
will be available. Copies of the presentations will be distributed as 
PDFs. Participation is limited to 20 persons. Confirmation will be sent 
after pre-registration deadline.


*Content:*2 * 6 hours in total

Lectures:

- the Rietveld method and BGMN software

- use of the GUI Profex (Nicola Döbelin)

- profile modeling including clay structures

- problems related to quantitative phase analysis

Tutorials:- settings of laboratory XRPD instruments

- simulation and check of instrumental profiles

- computer exercises on prepared problems

- use of control files for phase quantification

- sources of errors in mineral quantification

*Lecturers:*Reinhard Kleeberg, Nicola Döbelin, Kristian Ufer

**

*Date:*March 12-13 2014

*Place:*TU Bergakademie Freiberg, Department of Mineralogy

Brennhausgasse 14

D-09596Freiberg

Germany

*Fees:*include workshop material and workshop diner

full registration170,- €

students reduced60,- €

*Accommodation:*

Please book your room on your own, e.g. via tourist service

http://www.klick-auf-freiberg.de/engl/index.htm

*Pre-registration:*

deadlineJanuary 24^th 2014

Email to the address below, with name, institution, student/no

*Contact:*Dr. Reinhard Kleeberg

Tel. 0049(0)3731 393244

Fax. 0049(0)3731 393129

Email kleeb...@mineral.tu-freiberg.de 
mailto:kleeb...@mineral.tu-freiberg.de



--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

++
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++

Re: negative peak

[Reinhard Kleeberg]

In my knowledge, this effect (an edge at about 6 deg 2th) comes from a 
scattering of the lower part of the tube housing/shutter window. This 
scattered intensity goes straight above the sample, directly into the 
detector when no more antiscatter optics follow. Therefore, it can be 
observed only without diffracted beam monochromator and without 
secondary beam antiscatter slit, typically with such 1D strip detectors. 
At our instrument (Empyrean) the effect was independent on the type of 
sample, occured even with an empty low-background holder.
The edge can be shifted towards lower angles by a knife edge scatter 
blocker above the sample, but of course this thing reduces the 
irradiated area on the sample at higher angles. Another, better 
possibility would be an additional antiscatter slit close to the tube 
shutter, but unfortunately there is no free position.


Another strange thing with our instrument is a kind of hump in the 
background at about 15-25°2theta, occurring only when the programmable 
divergence slit is used in combination with an 1D strip detector. With a 
secondary beam graphite monochromator/propcounter as well as when the 
programmable slit was chosen bigger than the primary beam fixed 
anti-scatter slit (tungsten rods), we did not observe this effect. 
Therefore, my interpretation of this intensity is 
fluorescence/scattering from the brass material of the programmable slit 
edges. Such instrumental background artifacts are not nice for Rietveld 
refinement, as they must be fitted by a modulated background model...


Reinhard

Am 21/11/2013 12:32, schrieb gre...@unisi.it:

with some materials, I observed powder diffraction patterns (Bragg-Brentano, 
X'pert) which
show a broad negative peak around 5-6º(2th), instead of the smoothly descending 
intensity
coming from the primary beam.

Did some of you observe the same phenomenon, and has this been dealt with 
anywhere?

best regards

Miguel

--
Miguel Gregorkiewitz
Dip Scienze della Terra, Università
via Laterina 8, I-53100 Siena, Europe
fon +39'0577'233810 fax 233938
email gre...@unisi.it





--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129

++
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++

Re: Instrumental resolution function

[Reinhard Kleeberg]

Tubetails are simply the result of emission of the target radiation from 
outside the wanted line focus, some mm around. Depending on tube 
quality, age and operating power, one can have varying shapes when 
projected on the 2theta scale. Examples:

http://www.bgmn.de/tubetails.html
As you can see, the shape are not hats as assumed in Topas but may have 
discrete maxima at both sides, may by assymetric.
Especially for sharp peaks, the correction strongly improves the result 
of profile fitting:


Bergmann, J., Kleeberg, R., Haase, A., Breidenstein, B. (2000) Advanced 
fundamental parameter model for improved profile analysis. Mat. Sci. 
Forum Vols. 347-349(2)303-308.



In general, the tubetails more strongly influence the peak shape for 
instruments with smaller goniometer radius and when the equatorial 
divergence slit is placed closer to the sample.
In general. Alan's statement that the width/shape of the tubetails is  
2Th independent is correct, as it is simply a projection on the 
measuring circle. But, as a part of the tubetails diffracted intensity 
is generated outside the projection of the wanted focus via the 
divergence slit on the sample, tubetails may be cut by a limited size of 
the sample. Such cutting of the tubetails effect may happen at low 
angles for fixed slit systems and at higher angles when using automatic 
slit systems. In consequence, the intensity and shape of the tails 
effect can become dependent on 2Theta, in a complicated way.
In BGMN/GEOMET we try to convolute an experimentally measured focus 
profile into the geometrical contribution of the MonteCarlo simulation. 
As this procedure is done at discrete angular steps and the resulting 
geometrical profiles are interpolated later, we hope to have introduced 
correctly such secondary effects.


Reinhard

Am 17/09/2013 03:53, schrieb Alan Coelho:

Matt


I am not sure I understand how you would account for the additional
wavelengths in the beam.

Tube tails is spectrally independent and its aberration shape is 2Th
independent. Its realized in TOPAS by a convolution called stacked_hats
which, as its name suggests, convolutes a series of stacked impulse
functions. An intense narrow hat represents the beam and wider hats the
penetration of the electrons in the tube.

Cheers
Alan

-Original Message-
From: Matt Beekman [mailto:matt.beek...@oit.edu]
Sent: Tuesday, 17 September 2013 2:08 AM
To: Peter Y. Zavalij; Alan Coelho; mariomac...@tux.uis.edu.co;
rietveld_l@ill.fr
Subject: RE: Instrumental resolution function

Alan, Peter,

Would you mind briefly elaborating on the procedure used to fit tube
tails? I personally have only used GSAS for Rietveld refinement, and other
than adding another phase(s) with slightly different lattice parameter(s) I
am not sure I understand how you would account for the additional
wavelengths in the beam.

Many thanks in advance!

Matt

--
Matt Beekman, Ph.D.
Assistant Professor of Physics
Department of Natural Sciences
Oregon Institute of Technology
3201 Campus Drive
Klamath Falls, OR 97601
Tel: 541-885-1940
Fax: 541-885-1849
Email: matt.beek...@oit.edu
Web:
http://www.oit.edu/faculty-staff/home-pages/natural-science/matt-beekman



-Original Message-
From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf
Of Peter Y. Zavalij
Sent: Monday, September 16, 2013 6:11 AM
To: Alan Coelho; mariomac...@tux.uis.edu.co; rietveld_l@ill.fr
Subject: RE: Instrumental resolution function

I do exactly the same - fit tube tails using LaB6 standard and use the
parameters (usually w/o fitting) in all other refinements. Although tube
tails fitting helps a lot it's not perfect.
Peter Zavalij

-Original Message-
From: Alan Coelho [mailto:alancoe...@bigpond.com]
Sent: Sunday, September 15, 2013 10:05 PM
To: Peter Y. Zavalij; mariomac...@tux.uis.edu.co; rietveld_l@ill.fr
Subject: RE: Instrumental resolution function

Hi Peter, Mario

I happen to have a Ni filter, Cu, LaB6 pattern  that has a very similar look
to the one sent by Mario. Probably best to look at the 21.35 degrees 2Th
peak. The Ni filter cut-off occurs at 20.6 degrees 2Th, the satellite group
is hard to see due to the low angle and hence compression of the emission
profile. What made sense in the pattern was to fit Tube tails. Across the
whole patter the Rwp was reduced by 2.1% where Tube tails was considered and
the fit at the shoulders was good.

Cheers
Alan


-Original Message-
From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf
Of Peter Y. Zavalij
Sent: Monday, 16 September 2013 10:55 AM
To: mariomac...@tux.uis.edu.co; rietveld_l@ill.fr
Subject: RE: Instrumental resolution function

Hi Mario,
The shoulder you observe is what's left from white after it is cut off by
beta-filer. You could check the absorption edge of Ni and it is right at the
shoulder you observe.
Peter

__
Peter Zavalij
X-ray Crystallographic Center
University of Maryland
College Park, 

Re: Negative Uiso in GSAS

[Reinhard Kleeberg]

To add some more simple reasons for apparently overmuch high intensity 
at high angles causing meaningless negative temperature factors:
- the low angle peak intensities are suppressed by beam overflow 
(typically fixed slit Bragg Brentano geometry)
- one is using automatic slit data instead of fixed slit ones, and the 
program used is unable to account for that
- if one has used converted ADS data to fixed slit data: The conversion 
failed because of any wrong background correction, or the primary ADS 
data are wrong because of misprogramming or misalignement of the ADS system.


And one addition to Jon's important point 5 below: This is often related 
to physically meaningless peak shape models, running out of meaningful 
peak width values, just by becoming broader and broader and taking 
intensity from the background into the high angle peak intensities. One 
should use a physically based and more rigid peak shape model.


Regards

Reinhard


Jon Wright schrieb:

I can't resist adding one more to Mike's excellent list:

5. When peaks overlap strongly it becomes difficult to determine the 
background level. Negative Uiso is a consequence of the background 
refining to a value which is too low, especially where the peaks are 
most dense in the pattern (shorter d-spacings or higher angles).


All the best,

Jon

Michael Glazer wrote:

Negative U's in Rietveld can arise from several causes, so that there is
not one single answer. Some of the reasons are
1. The structural model is simply incorrect.
2. High absorption means that the low-angle data are weaker than they
should be, or conversely that the high-angle data appear stronger than
they should be. Abnormally strong high-angle data give rise to a
decrease in U's, even making them appear negative
3. Correlation between the refinement parameters. For instance U's will
tend to be highly correlated with site occupation parameters, often
making it difficult to separate them.
4. In general, many of the errors that one encounters tend to end up in
the refined U's, and this is why their precise values have to be treated
with caution.
Rietveld refinement (as opposed to single-crystal refinement) is in fact
refinement of degraded data (it is one-dimensional instead of
three-dimensional) and so the errors will be more significant.

Mike Glazer


-Original Message-
From: carolina.zip...@fi.isc.cnr.it
[mailto:carolina.zip...@fi.isc.cnr.it] Sent: 03 March 2010 16:08
To: rietveld_l@ill.fr
Subject: Negative Uiso in GSAS

Dear all,

could someone explain to me the meaning of obtaining a negative Uiso in
GSAS?
I thought it was always positive...(p. 123 manual)

thanks

Carolina


_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-


  Dr. Carolina Ziparo

   Istituto dei Sistemi Complessi - sezione di Firenze,
   C.N.R. - Consiglio Nazionale delle Ricerche

   via Madonna del Piano, 10
   I-50019 Sesto Fiorentino Italy


   tel.:   +39 055 5226693
   fax:+39 055 5226683
   e-mail: carolina.zip...@fi.isc.cnr.it



  

Re: Explaining for broadening of peaks due to a shift of theta in theta-two theta scanning?

[Reinhard Kleeberg]

Such an offset of the theta (omega) axis violates the para-focusing 
condition of the Bragg-Brentano geometry. You will get diffracted 
intensity from positions far below and above the gonimeter axis, i.e. 
far outside the focusing circle. The only option to reduce this effect 
is a reduction of the divergence of the primary beam. Without parallel 
beam optics, you can just reduce the opening of the equatorial slit, of 
course causing significant loss of intensity.

Reinhard Kleeberg

Huy LE-QUOC schrieb:

Dear Rietvelders,

To avoid the gigantic peaks of Si substrate (which are too dominant 
over peaks of phases in investigation on a thin film of 3 micron), we 
have tried to take a scan theta-two theta with a shift of 3 degree for 
theta (i.e. instead of theta-2theta corresponding to 5-10 degree at 
the beginning, I have set theta=8 degree and 2theta=10). In fact, we 
have been able to reduce dramatically intensity of Si peaks but the 
broadening of all peaks in the diffractogram is increased comparing to 
the normal scan without shift of theta.
We have also tried to rotate the sample around its perpendicular axis 
(angle Phi) to find the appropriate Phi where the peaks of Si are 
slightly decreased and found that the broadening of peaks is the same 
as in a normal theta-2theta scan.


Does anyone have any ideas about this increased broadening of peaks 
during a theta-2theta scan with theta shifted ?


By the way, do you know others ways, besides the razing incidence, to 
avoid the dominant peaks of substrate over the thin film  ?


Thanks a lot in advance for your any helps.

Best regards,

---
Huy LE-QUOC,
Doctorant
LPSC/UJF-Grenoble INP-CNRS, Centre de Recherche 
Plasmas-Matériaux-Nanostructures
Institut Néel/CNRS, Département Matière Condensée, Matériaux et 
Fonctions

53 rue des Martyrs, Grenoble 38026, FRANCE
Phone: +33 4 76 28 40 38
Fax:   +33 4 76 28 40 11

Re: Automated slits for Panalytical MPD

[Reinhard Kleeberg]

The clear advantage of variable slit is to have more intensity at 
medium/higher diffraction angles, compared to fixed slit systems adapted 
to low starting angles. This is nice for quantitative Rietveld analysis 
of samples having important intensities at low as well as at medium/high 
angles, e.g. clay minerals (00l and 060 reflections). I personally love 
variable slit measurements with our old (conventional detector) 
instruments for routine quantitative Rietveld analysis, showing good 
peak-background ratio and pure alpha1/alpha2 doublet (because of 
graphite monochromator, traditional point detectors), combined with 
acceptable high intensity from the variable slit.
Of course, any data treatment like internal conversion from variable 
to fixed-slit data (as recommended/necessary in some old-fashioned 
software) before Rietveld analysis should be avoided.
As David wrote, it is no big deal to model the instrumental function for 
variable slits (inclusive the intensities) in a fundamental parameter 
approach, allowing  even a reasonable structure refinement, see

http://www.bgmn.de/vardiv.html
However, practical problems may arise at very high angles resp. very 
high opening of the variable slit, if the slit divergence reaches the 
magnitude of the tube take-off angle or the breadth of the 
diffracted-beam monochromator. This cannot be correctly modeled by the 
Monte-Carlo simulation, simply because the intensity distribution within 
the broad tube beam bundle and the precise position and dimension of the 
curved monochromator are unknown/uncertain. So extreme slit opening 
should be avoided even with a fundamental parameter modeling.


Reinhard Kleeberg

David Lee schrieb:
The only advantage I see with a variable slit is that you keep a 
constant area on the surface.  This
gives a constant sampling volume for samples that are thin compared to 
the x-ray penetration depth.
In contrast, the sampling volume is fixed with a thick sample and 
fixed slit for typical powder samples.


  I agree that the variation in resolution with angle makes Reitveld 
analysis much harder.  A full fundamental

parameter analysis software  that includes the variable slit might work.

David Lee, Ph.D.
DTLee Scientific, llc
http://www.dtlee.com
614-562-6230

On Dec 7, 2009, at 10:03 PM, Russ Field wrote:


HI All

I am seeking opinion on the installation of automated slits on a 
Panalytical MPD


Pros and cons.

Comments from a previous post are shown below by an esteemed colleague

I see little use for varable divergence slits for all sorts of 
reasons  (firstly as there is no rock solid conversion from automatic 
to fixed intensities, secondly the resolution changes with angle with 
variable slits that can't be modelled

unless a more sofisticated model than that of Highcore Plus
is used).


Regards

Russell

Russell Field BSc (Hons),
Scientific Officer,
Dept of Physical Geography,
Macquarie University,
NSW 2019
==
Ph: 02 9850 8341
Fax: 02 9850 8420
Mobile No. 0417 681 959
Email: rfi...@els.mq.edu.au

Workshop BGMN February 2010

[Reinhard Kleeberg]

Dear colleagues,
we are happy to announce a workshop Rietveld analysis with BGMN at 
February 25-26, 2010, in Freiberg/Germany.


The workshop is addressed to persons using or planning the use of the 
BGMN Rietveld program in research and industry. Basic knowledge in X-ray 
powder diffraction is assumed. The content focuses on the application in 
phase analysis, and examples in the tutorials are mainly from minerals 
and rocks, inclusive clay materials.
The computer exercises will be performed on the participant’s own laptop 
computers. Persons who have no licensed BGMN program will be provided by 
a full version with time-limited usability. Versions for Windows, Linux, 
and MAC systems will be available. Users of Windows Vista must have 
administrator rights to install the program.

Copies of the presentations will be distributed as PDF or printed handout.
The number of participants is limited to 20 persons. Confirmation will 
be sent after pre-registration deadline (30 November).


Content: 2 days a 6 hours
Lectures: - physical basics of XRPD, related to laboratory data
- introduction in the Rietveld method and BGMN
- profile modeling including clay structures
- problems related to quantitative phase analysis
Tutorials: - computer exercises on prepared problems
- creation of instrumental profiles
- use of control files for phase quantification
- modification of simple structure models
- sources of errors in phase quantification
Discussion

Lecturers: Reinhard Kleeberg, Jörg Bergmann, Kristian Ufer

Date: 25-26 February 2010

Place: TU Bergakademie Freiberg, Department of Mineralogy
Brennhausgasse 14
D-09596 Freiberg
Germany

Fees: include workshop material and workshop diner
full registration 150,- Euro
students reduced 50,- Euro

Accommodation:
Please book your room on your own, e.g. via tourist service
http://www.klick-auf-freiberg.de/engl/index.htm

Pre-registration:
deadline 30 November
Email to the address below, with name, institution, student/no

Contact: Dr. Reinhard Kleeberg
Tel. 0049(0)3731 393244
Fax. 0049(0)3731 393129

Re: Comment on Ball Miller

[Reinhard Kleeberg]

It is not recommended to use a ball mill for PXRD sample prep: This type
of mills has a small (point) active grinding surface and applies a high
energy to this point. As a result, you will get a broad particle size
distribution, including a number of overmuch big grains and a high
degree of amorphization respectively additional defects in the material.
Narrow particle size distribution with a minimum of structural damage
can be obtained by wet grinding in mills with high active grinding
surface (big number of smal grinding elements), e.g. the McCrone
micronizing mill.
See:

Hillier, S. (2003) Quantitative analysis of clay and other minerals in
sandstones by X-ray powder diffraction (XRPD). International Association
of Sedimentologists Special Publication, *34*, 213-251.

Reinhard

[EMAIL PROTECTED] schrieb:

 Dear all rietvelders,

 Do anyone of you use the ball miller for PXRD sample preparation?
 Since I am going to buy one such system. Any comment is highly
 appreciated.

 many thanks in advance

 stephen

Re: [sdpd] calibration problems with Silicon+gsas

[Reinhard Kleeberg]

The background looks suspicious oscillating, not simply noisy. Maybe 
there are some problems with the PSD or generator stability (e.g. 
oscillating of cooling water temperature), or any internal or external 
data treatment (e.g. smoothing, interpolation..) was applied?
Additionally, your profile fit is far from beeing acceptable. As 
Professor LeBail was able to do it better without structure in Fullprof, 
you should look for a better peak profile model in GSAS.

Reinhard Kleeberg

[EMAIL PROTECTED] schrieb:


Hi, All:
This morning i tried further refinement work and eventually i got a R 
value of 0.0518.

As a conlusion, the critical steps are summarized:
*Step 1*--origin selection: Thanks to the suggestion from Prof. 
Gottschalk, i took (1/8,1/8,1/8) origin instead of (0,0,0). It is much 
improved and it shows the calibration sample has no problem, but 
current match cannot be better enough. R-0.3578
*Step 2*--radiation wavelength and pola: Under the suggestion from 
Prof. Gottschalk, i took the lamda=1.54056 and Pola=0.78989 instead. 
R-0.2205

*Step 3*--Release Uiso refinement: after that,R-0.1563
*Step 4*--Start to refine background parameters. Diffuse scattering 
was also introduced without refinement(3-type, A=1.0, 
R=2.352,U=0.005), although it helped not much and neither of ARU can 
be refined without divergency. R- 0.0518
The current .exp file, as well as related pictures, can also be 
downloaded via: http://www.physik.uni-augsburg.de/~lujun/ 
http://www.physik.uni-augsburg.de/%7Elujun/
The current R value of 0.0518 is acceptable in average. Our instrument 
was not so bad. :)
Nevertheless, whether the device's state was suitable for refinement 
analysis or not is still unclear, and i still doubt whether the 
peakshapes produced by the device can be well descriped by type-3 
parameters.
i am also doubting whether this rough parameters, as shown below, are 
somehow reproducible for other materials when all the measurement 
conditions are the same.
Moreover, the background looks quite bad, where the variation of 
intensities is about 2000, resulting in high chi2 ~ 30! i saw normal 
background oscillation is about 20-50 and good fitting gives chi2 less 
than 2.
At present, to fix the remaining problem make our refinement in other 
materials reliable and reasonable, what we plan to do is:
1. optimize the experimental conditions and redo the measurement for 
silicon several times;

2. buy a new package of standard silicon powder;
3. ask technique supports from the manufacturer of our instrument.
Thanks for your attention! Specially thank Prof. from 
GeoForschungsZentrum Potsdam.
We will be engaged to the business of careful instrument calibration 
in the following weeks.

Further comments will still be quite welcomed!
By the way, Thanks to kind Prof. Le Bail, our calibration raw data has 
been tried using FullProff tools.
Thoes interested FullProf experts can visit the package via this web 
page, http://www.physik.uni-augsburg.de/~lujun/Si-fullprof.html 
http://www.physik.uni-augsburg.de/%7Elujun/Si-fullprof.html. Note: 
this primary trial is currently without fine structure 
information(from Prof. Le Bail)


Faithfully
Jun Lu
--
Lst. Prof. Lijie Qiao
Department of Materials Physics and Chemistry
University of Science and Technology Beijing
100083 Beijing
P.R. China
http://www.instrument.com.cn/ilog/handsomeland/
Lst. Prof. Loidl and Lunkenheimer
Experimental Physics V
Center for Electronic Correlations and Magnetism (EKM)
University of Augsburg
Universitaetsstr. 2
86159 Augsburg
Germany
http://www.physik.uni-augsburg.de/exp5

- Original Message -
*From:* Matthias Gottschalk mailto:[EMAIL PROTECTED]
*To:* [EMAIL PROTECTED] mailto:[EMAIL PROTECTED]
*Sent:* Tuesday, June 10, 2008 7:39 PM
*Subject:* Re: [sdpd] calibration problems with Silicon+gsas

Ok, just as I thought.
It is the wrong atom position. 0 0 0 has in the default
origin setting a multiplicity of 16 and not 8. So put the
Si on 1/8 1/8 1/8 and then all will work. Some additional
remarks.

1. Set POLA to 0.78989 because you have probably a primary
monochromator, too.

2. Set the wavelength to 1.54056

3. Use the profile function 2

4. Write an parameter file (using EXPGUI) for your Stadi P
which also includes the GU, GV, GW, LX, and GY parameters
refied for this sample. Only use these parameters.

5. To get a meaningful Durbin-Watson factor your
intensities are to high. For a cubic phase use maximum
intensities in the order of 1 (8000-1) to get
reasonable statistics and esd`s.

6. Use difuse scattering for your background.

Matthias Gottschalk

On Tue, 10 Jun 2008 19:05:35 +0200
[EMAIL PROTECTED] [EMAIL PROTECTED]
mailto:jun.lu%40physik.uni-augsburg.de wrote:
 Hello again, everyone:

 i have just received a reply from Prof. Stephens,
indicating some problems about the attachment.
 i am so sorry

Re: ADS

[Reinhard Kleeberg]

Periclase is really problematic because of the small number of peaks in 
the usual angular range used for QPA with Cu or Co radiation. Thus, the 
particle statistics problem becomes extremely critic, as Pamela already 
said. The uncertainties can be compared with the statistical intensity 
errors of a single line. See also the textbook of Klug  Alexander 
(1954), section operation of the spectrometer, specimen preparation, 
demonstrating that the mean statistical error of the intensity of the 
biggest line of quartz of a 15-50 µm fraction is 18.2 %!.
Other systematic errors may result from the description of the peak 
profile: If you have only 3-4 peaks, only one peak having significant 
intensity bigger than the noise, than the profile shape model of this 
peak must be fit perfectly to get a correct intensity fit resp. correct 
scale factors. In my opinion, this is hard to do with converted data. 
Intensity conversion does not converge the instrumental effect on the 
profile shapes. Thus, any physical meaning of profile parameters goes 
lost by data conversion, as well as the counting statistics (noise) are 
changed by the conversion. In general, Rietveld refinement should not be 
done with corrected or modified diffraction data because of the 
weighting scheme of the minimization procedure supposes unchanged 
counting statistics. You should use a Rietveld program what is able to 
refine unchanged ADS data by a physically based peak profile model.
But even if these things are done correctly, an accuracy of  0.5 wt% of 
a minor phase in a complex system like cement can only be acchieved by a 
very optimized procedure, from perfect sample prep over high quality 
measuring data up to an optimized Rietveld model.

Reinhard

Whitfield, Pamela schrieb:

I’m afraid that 30 microns might be small to the eye but is too big 
for quant analysis. The particles need to be in the range of a micron 
or two. There’s an old paper by Deane Smith that did a brilliant job 
of showing the effects in a statistical manner.


Pam

*From:* José Carlos Cordeiro [mailto:[EMAIL PROTECTED]
*Sent:* May 29, 2008 5:07 PM
*To:* Whitfield, Pamela; rietveld_l@ill.fr
*Cc:* Mitchell, Lyndon
*Subject:* RES: ADS

My samples are cements (fine samples with 30 microns) and don’t need 
micronize its. The problem in my refinements is that periclase 
quantified with fixed slit is bigger than MgO by Fluorescence, and its 
impossible. Ex:


Periclase with fixed slit: 7,14%

MgO by XRF = 6,84%

We know that part of MgO (1,5-2,0%) go to the structure of C3S an C2S 
phases, so periclase expected in this sample is 4,8% - 5,3%. If we 
consider this, the errors of refinement is not very slim.


Sorry for my bad English!!!

regards

*===*

*José Carlos Cordeiro*

*Diretoria Técnica - Laboratório Central*

Centro Técnico - Curitiba

Rodovia PR-092, 1303, Abranches, 82130-570 Curitiba-PR

Votorantim Cimentos

[EMAIL PROTECTED] mailto:[EMAIL PROTECTED]_

_www.votorantimcimentos.com.br _

Fone: + 55 041 3355-1380

Fax: + 55 041 3355-1358

===

-Mensagem original-
*De:* Whitfield, Pamela [mailto:[EMAIL PROTECTED]
*Enviada em:* quinta-feira, 29 de maio de 2008 17:40
*Para:* José Carlos Cordeiro; rietveld_l@ill.fr
*Cc:* Mitchell, Lyndon
*Assunto:* RE: ADS

Hi Jose

Errors in the region of 1wt% aren't unheard of in complex mixtures 
(and the liklihood of the second decimal place being meaningful is 
very slim). However there are other possible explanations and one in 
particular comes to mind.


Did you micronize your sample? If yes then feel free to ignore the 
following! If not then it might be worth thinking about.


We did a systematic study on the effect of particle statistics on the 
repeatability of quantitative analysis on one of the NIST cements last 
year (presented at the ICCC in Montreal - should really go somewhere 
more accessible). We compared different divergence slits, micronized 
and unmicronized samples, spun and static, and remounted/repeated the 
experiments 3 times each for real statistics as opposed to esds.


Funnily enough the phase that showed the biggest anomaly in one of the 
unground sample was the periclase - obviously a big (by XRD standards) 
lump fell into the sample from the kiln that made up the NIST batch 
and made it through the mill at the plant. Without grinding it we got 
0.1, 0.1 and 2wt% one series of 3, versus 0.6, 0.6 and 0.6 wt% (this 
is from memory so don't don't quote me!) for the micronized sample.


This was the result that we should have got theoretically but it was 
nice to see it work in practice, and the periclase did such a nice job 
for us by sticking out like a sore thumb even without a Rietveld 
analysis! BTW there was no statistically significant difference (95% 
limits) in the results of the C3S and C2S phases between ground and 
unground samples - mostly because the errors in the unground samples 
were so large! The 

Re: RES: ADS

[Reinhard Kleeberg]

Hi Lubo,
the difference between 6 and 7 % MgO is bigger than 15 % relatively, 
thus the error by wrong re-scaling (e.g. if 10 % amorphous are 
missing) is smaller than the error discussed. And, if the true content 
of periclase should be about 5 %, than a measured value of 7 % is worth 
to be discussed to be a real systematic error. This is an 
over-estimation by 40 %.
In the very past (30 years and more ago) people who applied single line 
methods carefully have been able to determine simple phases like free 
lime, quartz, anatase in low concentrations very accurate (of course 
after optimizing their technique), and I believe that such methods are 
still in use in routine product control. So I feel it is worth to think 
about why a Rietveld refinement should perform worse.
I agree with you that the cement business is full of dubious 
advertisement for machines and methods for accurate QPA. But this is not 
a reason to finish thinking about  how to improve QPA methods.

Best
Reinhard

Lubomir Smrcok schrieb:


Hi,
I really wonder why do you bother about 1% difference when the error 
of the method (XRD, quantitative phase analysis) could reach 10% 
(absolute) ...

People in the discussions appearing here seem to forget about two things:

i) quantitative phase analysis done by rietveld method is always 
re-scaled to 100%, i.e. the accuracy of % attributed to the individual 
phase directly depend on %'s attributed to the another phases present 
in the mixture (i.e. when you forget or ignore one phase having 10% 
share, those %'s are redistributed among the other phases);


ii) this method completely ignores any amorphous parts (i.e. those not 
providing Bragg peaks, to be more exact) - ignores, because it cannot 
do anything else about it. Obviously, when you compare XRF and XRD you 
can find yourself in troubles as XRF dos not bother about the state of 
the compounds.


Finally, my personal advice. If someone tells you you can analyze 
clinkers or even cements by XRD accurately, do not trust him. He, most 
probably, thinks of selling you a machine you can hardly use for this 
purpose :-)

Bad luck if you have already bought it ...

Best,
Lubo



On Thu, 29 May 2008, [iso-8859-1] José Carlos Cordeiro wrote:

My samples are cements (fine samples with 30 microns) and don't need 
micronize its. The problem in my refinements is that periclase 
quantified with fixed slit is bigger than MgO by Fluorescence, and 
its impossible. Ex:




Periclase with fixed slit: 7,14%

MgO by XRF = 6,84%



We know that part of MgO (1,5-2,0%) go to the structure of C3S an C2S 
phases, so periclase expected in this sample is 4,8% - 5,3%. If we 
consider this, the errors of refinement is not  very slim.




Sorry for my bad English!!!



regards



===

José Carlos Cordeiro

Diretoria Técnica - Laboratório Central

Centro Técnico - Curitiba

Rodovia PR-092, 1303, Abranches, 82130-570 Curitiba-PR

Votorantim Cimentos

[EMAIL PROTECTED] mailto:[EMAIL PROTECTED]

www.votorantimcimentos.com.br

Fone: + 55 041 3355-1380

Fax:   + 55 041 3355-1358

===

-Mensagem original-
De: Whitfield, Pamela [mailto:[EMAIL PROTECTED]
Enviada em: quinta-feira, 29 de maio de 2008 17:40
Para: José Carlos Cordeiro; rietveld_l@ill.fr
Cc: Mitchell, Lyndon
Assunto: RE: ADS



Hi Jose



Errors in the region of 1wt% aren't unheard of in complex mixtures 
(and the liklihood of the second decimal place being meaningful is 
very slim).  However there are other possible explanations and one in 
particular comes to mind.


Did you micronize your sample?  If yes then feel free to ignore the 
following!  If not then it might be worth thinking about.




We did a systematic study on the effect of particle statistics on the 
repeatability of quantitative analysis on one of the NIST cements 
last year (presented at the ICCC in Montreal - should really go 
somewhere more accessible).  We compared different divergence slits, 
micronized and unmicronized samples, spun and static, and 
remounted/repeated the experiments 3 times each for real statistics 
as opposed to esds.




Funnily enough the phase that showed the biggest anomaly in one of 
the unground sample was the periclase - obviously a big (by XRD 
standards) lump fell into the sample from the kiln that made up the 
NIST batch and made it through the mill at the plant.  Without 
grinding it we got 0.1, 0.1 and 2wt% one series of 3, versus 0.6, 0.6 
and 0.6 wt% (this is from memory so don't don't quote me!) for the 
micronized sample.


This was the result that we should have got theoretically but it was 
nice to see it work in practice, and the periclase did such a nice 
job for us by sticking out like a sore thumb even without a Rietveld 
analysis!  BTW there was no statistically significant difference (95% 
limits) in the results of the C3S and C2S phases between ground and 
unground samples - mostly because the errors in the 

Re: RES: ADS

[Reinhard Kleeberg]

Hi Pam,
maybe a misunderstanding: I did not try to discuss the amount of 
amorphous material in cements. I'm aware of the problem, but a 
careful  Rietveld analysis with an internal standard should be able to 
determine at least the magnitude of the amorphous part. Even if not 
(e.g. if profile errors or structural uncertainties of the clinker 
phases do prohibit a reliable quantification of the amorphous), a 
systematic error of 7 instead of 5 wt% for a highly symmetric phase with 
well resolved peaks like periclase is neither acceptable nor 
unavoidable. And in my opinion a careful sample prep, measurement and 
Rietveld analysis (maybe with internal standard) should be able to 
perform better. I only tried to relativise Lubo's general denial of the 
potential of quantitative phase analysis to reach an accuracy of about 1 
wt%. Maybe I'm simply more optimistic than Lubo ;-)

Reinhard

Whitfield, Pamela schrieb:


Hi Reinhard
 
Saying the words amorphous content and cement in the same breath is 
heresy in many circles!  Personally I think that it's a case of 'see 
no evil, hear no evil'!
Anyway, many moons ago we did yet another study on the amorphous 
content in clinkers/cements and they can vary alot - we found up to 
20wt% in some.  The amount probably depends on the kiln conditions, 
alkali metal content and quenching rate.
Anyway don't take my word for it, Lerch and Brownmiller did a lovely 
bit of work (sadly forgotten) in 1937 using quenching in mercury (?!) 
and calorimetry yielding amorphous contents in clinker between 
10-28%.  The Ruland method has also been used to show significant 
amorphous contents in the various components of cement.
 
In my opinion the cement companies are probably more interested in 
consistency rather than accuracy to track changes in their process.  
Case in point - strictly speaking the XRF samples should be micronized 
(or fused) as well as the XRD ones - the XRF errors from the matrix 
effects of a 30micron cement in a pressed pellet are not exactly ideal.
 
I would agree that it's worth trying to push the boundaries of QPA.  
All is not lost for cements though - I saw the results of a test that 
Mati Raudsepp did with a very messy synthetic mineral mixture that 
looked completely ridiculous with the number of phases, but the result 
matched the weighing figures quite nicely.
 
Pam



*From:* Reinhard Kleeberg [mailto:[EMAIL PROTECTED]
*Sent:* Fri 30/05/2008 5:36 AM
*To:* rietveld_l@ill.fr
*Subject:* Re: RES: ADS

Hi Lubo,
the difference between 6 and 7 % MgO is bigger than 15 % relatively,
thus the error by wrong re-scaling (e.g. if 10 % amorphous are
missing) is smaller than the error discussed. And, if the true content
of periclase should be about 5 %, than a measured value of 7 % is worth
to be discussed to be a real systematic error. This is an
over-estimation by 40 %.
In the very past (30 years and more ago) people who applied single line
methods carefully have been able to determine simple phases like free
lime, quartz, anatase in low concentrations very accurate (of course
after optimizing their technique), and I believe that such methods are
still in use in routine product control. So I feel it is worth to think
about why a Rietveld refinement should perform worse.
I agree with you that the cement business is full of dubious
advertisement for machines and methods for accurate QPA. But this is not
a reason to finish thinking about  how to improve QPA methods.
Best
Reinhard

Lubomir Smrcok schrieb:

 Hi,
 I really wonder why do you bother about 1% difference when the error
 of the method (XRD, quantitative phase analysis) could reach 10%
 (absolute) ...
 People in the discussions appearing here seem to forget about two 
things:


 i) quantitative phase analysis done by rietveld method is always
 re-scaled to 100%, i.e. the accuracy of % attributed to the individual
 phase directly depend on %'s attributed to the another phases present
 in the mixture (i.e. when you forget or ignore one phase having 10%
 share, those %'s are redistributed among the other phases);

 ii) this method completely ignores any amorphous parts (i.e. those not
 providing Bragg peaks, to be more exact) - ignores, because it cannot
 do anything else about it. Obviously, when you compare XRF and XRD you
 can find yourself in troubles as XRF dos not bother about the state of
 the compounds.

 Finally, my personal advice. If someone tells you you can analyze
 clinkers or even cements by XRD accurately, do not trust him. He, most
 probably, thinks of selling you a machine you can hardly use for this
 purpose :-)
 Bad luck if you have already bought it ...

 Best,
 Lubo



 On Thu, 29 May 2008, [iso-8859-1] José Carlos Cordeiro wrote:

 My samples are cements (fine samples with 30 microns) and don't need
 micronize its. The problem in my refinements is that periclase
 quantified with fixed slit is bigger than MgO

Re: Preferred orientation?

[Reinhard Kleeberg]

Luca,
I understood Gerard's problem to have a measurement of a powder (of 
unknown particle shape) in Bragg-Brentano geometry, for structure 
refinement. As you said the graininess problem can be minimized 
primarily by grinding and to a certain extent by rotation and enhancing 
the divergence, axial as well as equatorial. It is obvious that overmuch 
graininess would prohibit any reasonable structure refinement or 
quantitative phase analysis, with or without the application of a 
harmonic model for intensity correction.
Regarding the PO of powder mounts produced from minerals (big crystals) 
by grinding (McCrone mill, particle size 1-5 µm) and front- back- or 
sideloading the powder we must state that it is frequently present, of 
course strongly dependent from the particle shape (by cleavage) of the 
crystals. Not only platy or needle-like crystals tend to PO, but also 
cubes (e.g. halite), octahedra (e.g. fluorite), rhombohedra (e.g. 
calcite), pinakoids (e.g. feldspars) show PO because such crystals tend 
to stacking and orientation face by face, like bricks, in a real 
powder mount. The variation of the preparation technique (say 
sideloading instead of frontloading) does induce changes in PO what can 
be used to identify PO, as I understood Frank's recommendation. This is 
indeed the trick we apply every second week if a sample is suspicious 
to be not adequately prepared. I remember also that an intentionally 
enhancement of PO by preparation may also be applied for indexing and to 
add information in structure refinement (of multiple patterns, McCusker..).
Of course the degree of orientation in such prepared powder samples is 
probably not as high as in your real textured samples, but m.r.d.'s in 
the magnitude of 3 (or down to 0.5) may appear. I believe this is weak 
texture in the context of texture analysis? For such (in my opinion also 
real and textured) powder samples, a model similar to the harmonics 
works fine for PO correction, provided that enough measurable peaks are 
in the pattern. E.g. the application of a model having 3 parameters to a 
cubic material showing only 2 different lattice planes in the 
one-dimensional scan must fail of course. Other problems may arise when 
two directions (e.g. h00 and 0k0) show strongly overlapping peaks by 
pseudo-symmetry, or when the intensity of a lot of hkl is very week for 
structural reasons. In all these cases the one-dimensional powder 
pattern contains not enough information to apply such a harmonic model, 
the model must be deactivated, a better (more random) sample must be 
prepared, the number of peaks must be enhanced... Thus, any  PO 
correction in Rietveld refinement is second-best solution only.
But in the daily routine work in Rietveld phase analysis, we can see 
that in the most cases the calculated PO correction factors are 
reasonable (reflecting the shape of the crystals, biggest faces get 
highest, directions inbetween lowest...), and the quantitative results 
are acceptable for such realisticly oriented powder samples what can 
produced by standard techniques.  I believe this is an argument to apply 
these models, even though they are perhaps not able to decribe stronger 
PO or maybe unable to do a texture analysis (what is anyway impossible 
from a single Bragg-Brentano scan).

Greetings
Reinhard

Luca Lutterotti schrieb:


Reinhard,

I stick with what Gerard said:

But i have no other information that supports the existence of  
preferred orientation


so what information give you the confirmation it is the powder mount  
responsible of preferred orientation. I work almost exclusively with  
image plate detectors and I can assure you that the graininess 
problem  is appearing more often than the preferred orientation case. 
I am  working on texture mostly so I am happy when you find them, but 
this  case is not s frequent as people think and for sure not s 
frequent as  graininess.


I wait also confirmation from Gerard that his sample is a powder and  
it has plate like or fiber like particles. Otherwise I will  
investigate the graininess case that with a proper grinding or a  
spinner is easily resolvable.


Also, for who think that because the harmonic model can fit it is for  
sure preferred orientation. I can just suggest to work for a while  
with real textured sample and the harmonic and see if there is really  
this relationship, you may be surprise by the result.


cheers,
Luca

On May 8, 2008, at 3:08 PM, Reinhard Kleeberg wrote:


Luca,
speaking about powder samples, Frank is right. The PO of powder  
mounts is seldom reproducible and the filling technique is  
responsible for particle orientation, depending on particle shape,  
filling direction, pressure... In practice it is a nice trick to  
repeat the filling of the powder holder with different filling  
techniques to look for PO. Of course, sample graininess may be also  
a reason for not reproducible intensity, but these effects (rocks  
in the dust

Re: Preferred orientation?

[Reinhard Kleeberg]

Luca,
speaking about powder samples, Frank is right. The PO of powder mounts 
is seldom reproducible and the filling technique is responsible for 
particle orientation, depending on particle shape, filling direction, 
pressure... In practice it is a nice trick to repeat the filling of the 
powder holder with different filling techniques to look for PO. Of 
course, sample graininess may be also a reason for not reproducible 
intensity, but these effects (rocks in the dust) ar mostly hard to 
correct successfully by spherical harmonics as Gerard stated for his 
problem. In any case, the problem sounds to be related to sample 
preparation.

Reinhard

Luca Lutterotti schrieb:


On May 8, 2008, at 12:30 AM, May, Frank wrote:

You can check for texture effects (preferred orientation) by  
obtaining multiple patterns of the material.  It's realistic to  
expect some differences, but preferred orientation is manifest by  
not being able to replicate the pattern.




Not true,

preferred orientation or texture are perfectly reproducible, provided  
you use the same sample orientation. What is not reproducible and  
probably what Frank May is referring to is not preferred orientation  
but graininess or few big grains that do not guarantee the correct  
statistic. So if you need to check for graininess, you just move a  
little your sample, so the beam covers a different area on the 
sample.  If you think you have texturte, to check for it you have to 
change the  sample orientation to see a change. Beware that in a 
Bragg-Brentano  instrument turning around the axis normal to the 
sample surface is not  a valid change in orientation as nothing will 
change for texture; you  have to change the sample inclination instead 
(omega or chi).


Best Regards,

Luca Lutterotti





That's the simple test.  Let us know what you find.

Another issue for improper intensities is when the specimen is not  
sufficiently wide enough at low angles (typically below 20-degrees 2- 
Theta with copper radiation) and the x-ray beam does not fully  
impinge on the specimen.  The observed reflections in the low angle  
region will be less than calculated by a modelling program.


Frank May
Research Investigator
Department of Chemistry and Biochemistry
University of Missouri - St. Louis
One University Boulevard
St. Louis, Missouri  63121-4499

314-516-5098



From: Gerard, Garcia S [mailto:[EMAIL PROTECTED]
Sent: Wed 5/7/2008 8:57 AM
To: rietveld_l@ill.fr
Subject: Preferred orientation?



Dear all,

I have a laboratory Bragg-Brentano X-ray (Cu) pattern that shows  
intensity mismatches only at low angles, ie 20-50 2theta or 1.8 to 4  
Angstroms.
There are overestimated peaks and also underestimated peaks.I have  
tried to discard factors that might cause this problem:


The thermal parameters look sensible. Moreover, the data at high  
angle looks ok, so intensity transfer from low angle to high angle  
or vice versa does not seem to be the cause.


Atomic positions also look sensible. And again, data at high angle  
looks ok. Is the scattering angle dependence of the atomic positions  
the same as for the thermal parameters? (I cannot remember that, but  
i am pretty sure it is not).


Following the advice published in J. Appl. Cryst. 32, 36 (1999), the  
other factor that might cause this problem is preferred orientation:
I have tried to find a hkl dependence in the overestimated and  
underestimated peaks but i could not find any. If i try to model  
preferred orientation with spherical harmonics the problems  
disappears nicely. The problem is how to justify the existence of  
preferred orientation. The crystal system is orthorhombic. But i  
have no other information that supports the existence of preferred  
orientation.


Is there any other problem that I cannot think of?Is the preferred  
orientation correction masking any of these other problems I cannot  
think of?


Regards

Gerard





Heriot-Watt University is a Scottish charity registered under  
charity number SC000278.

Re: Amorphous content

[Reinhard Kleeberg]

We have positive experience with commercial ZnO pigments or chemicals, 
heated to 700°C for about 2 hours in air for recrystallisation of the 
amorphous ZnO or the spurious Zn carbonates/hydrates to get nearly 100% 
crystalline ZnO. In 1:1 mixtures of the best NIST corundum, we found no 
significant deviation in Rietveld quantification, and so we use it 
routineously as internal standard. Such ZnO shows separate particles of 
about 0.5 µm diameter what can be assumed to persist a grinding and 
allow an appropriate low phase-specific correction for microabsorption.
As Pamela stated, in case of the CeO2 one problem may be the absorption 
contrast between the materials. The problem can only minimised by (a) 
choosing an appropriate wavelength (as Pamela recommended Mo?), and/or 
(b) optimising/minimising the effect of the PARTICLE size of all 
constituents of the mixture. Thus, it is recommended to grind as fine as 
possible and then to look for the resulting particle size of the powder 
(e.g. by laser scattering). The particle size should at least fulfill 
the conditions of µ*D to be fine or medium given in
Brindley, G.W. 1945. The effect of grain or particle size on X-ray 
reflections from mixed powders and alloys considered in relation to the 
quantitative determination of crystalline substances by X-ray methods, 
Phil. Mag., Ser. 7, 36: 347-369.
In general, a correct mean particle size of the phases should used in 
the Brindley correction term.
In our experience, the mixing of the standard ZnO and the sample powders 
can cause problems like forming aggregates of the both materials. For 
example, if larger aggregates of ZnO persist in the sample one can get 
negative amorphous content because of the underestimation of the ZnO 
by microabsorption. In contrast, coarse aggragates of sample phases 
cause underestimation of these crystalline phases and result in 
pseudo-amorphous contents. Therefore we prefer admixing of the 
standard before grinding the sample to reach a really homogeneous 
mixture, assume the 0.5 µm particle size for Brindley correction of the 
scale factor of ZnO, and set an estimated particle size (mostly 1-4 µm) 
globally for the phases of the powdered sample, according to some 
experience regarding hardness and behaviour of the material in our mill.
However, the uncertainty of this estimated values can still 
significantly bias the result of quantification of the amorphous 
content, especially for heavily absorbing materials. This can simply 
checked by calculating the Brindley correction factors for linear 
absorption coefficients of the actual sample material and varying the 
particle size in a realistic interval.


Reinhard Kleeberg

Whitfield, Pamela schrieb:

At first glance it looks like a classic microabsorption problem, but I 
don’t have the linear absorption coefficients to hand. Using an 
internal standard with a too small absorption will tend to 
over-estimate the amorphous content. Ce versus Zn is a pretty big 
contrast for CuKa, even if the particle sizes are small enough. The 
whole point of that NIST series (674 I think) is that they were to be 
used as appropriate contrast matching standards for quant analysis, 
and were supposed to be quite different from each other.


Changing the wavelength to reduce the contrast (e.g. Mo) may help for 
that particular mix but probably won’t completely solve it.


Pam

*From:* Peter Y. Zavalij [mailto:[EMAIL PROTECTED]
*Sent:* November 15, 2007 9:07 PM
*To:* rietveld_l@ill.fr
*Subject:* Amorphous content

Hi,

I am trying to determine amorphous content using Rietveld refinement 
and internal standard. However resulting content of amorphous phase is 
really unrealistic.


Moreover testing the method using standards with known amorphous 
content does not clarify the situation. For example ZnO (NIST, 95% 
crystallinity) used as standard to determine amorphous content in CeO2 
(also NIST standard with 91% crystallinity) yield 25% of amorphous 
phase which is a little bit too much comparing with expected 9%.


We tested several different standards, mixtures and preparations, 
different diffractometers and software without much luck... Seems like 
something simple is missing...


Any clues?

Many thanks,

Peter Zavalij

X-ray Crystallographic Laboratory
Department of Chemistry  Biochemistry
091 Chemistry Building
University of Maryland
College Park, MD 20742-4454

Phone: (301)405-1861
Fax: (301)314-9121
E-mail: [EMAIL PROTECTED]
http://www.chem.umd.edu/facility/xray/

Re: fixed slits or fixed radiated length Bragg-Brentano XRPD

[Reinhard Kleeberg]

Wojciech pointed out an important issue regarding ADS measurements:

Wojciech Paszkowicz schrieb:


Dear All,

Additional comment concerning the usefulness of variable slits for structure
refinement: The angular distribution of the radiation from an X-ray tube is
not necessarily uniform, so using variable slits for collection of
Rietveld-refined (Bragg-Brentano geometry) data may imply the need for an
additional intensity correction for this effect. 

Because the intensity distribution versus take-off angle of a tube is a 
priori unknown, one must find an working compromise, see again our 
comments at

http://www.bgmn.de/vardiv.html
Our comment: Maximum divergence angle should be much less than take-off 
angle of X-rays from tube anode. The latter angle usually is 6°. 


An additional restriction of the maximum slit opening may be given by 
the limited length of a secondary beam monochromator. The crystal may 
act like a fixed antiscatter slit and may cut the intensity if a certain 
ADS divergence is reached. But this can be modeled by the Monte-Carlo 
approach.



Moreover, the opening of
the variable slits requires an extremely high precision mechanics so there
may be a doubt  concerning the smoothness of the flux variation with varying
two theta, at the given instrument.

This is true for conventional stepper-motor driven slits at low angles, 
say below 15 °2theta. In that range the smallest steps of the slit  may  
be too large to fix the irradiated sample length over two theta. But the 
intensity data at very low angles may be biased by a number of additonal 
factors like sample roughness and misalignment of the sample surface. 
Thus, high accuracy/reproducibility of the intensity at low angles 
cannot be expected at all, and excluding this range from the refinement 
is common practice.
For higher angles, my personal experiences with ADS are positive, even 
for older instruments (built from 1986 to 1995, from 3 different 
manufacturers, 3 different types of stepper-motor driven ADS systems). 
Other people have been less happy with their ADS system, see

Peplinski, B.  Wenzel, J. (2000) Mat.Sc.Forum, Vols. 321-324, pp. 144-149.
It should be pointed out that it is necessary to check the a alignment 
and programming of the ADS in the way that Ian Madsen recommended in a 
previous mail (refining the temperature factors of a known standard). 
See also the literatur cited above. For a first coarse check of the 
primary beam ADS, a simple look on a fluorescent screen with a scale 
during a measurement (2° step, 2 sec per step) helps to see coarse 
angular fluctuations of the irradiated length, for example by a wrong 
programming. To check the zero point alignment of the slit, a 
divergence slit scan from negative to positive opening at 0 °2theta 
without sample (of course at reduced tube power and with absorber) can 
be done. If the instrument or the control software is not flexible 
enough to do this, one should ask the manufacturer service for help 
respective for a demonstration that the ADS is correctly aligned.
It is clear that such additional efforts that are neccessary for the 
correct use of the ADS system (compared to fixed slit systems) must be 
counterbalanced to the advantages of an ADS. Here, everyone must do his 
own judging.

Regards
Reinhard Kleeberg

Re: fixed slits or fixed radiated length Bragg-Brentano XRPD

[Reinhard Kleeberg]

Hi,
as William Bisson stated, the main purpose of automatic divergence slits 
is to enhance the intensities at higher angles. But, the changes in 
intensity and profile shape compared to fixed slit systems are no 
mysterium. They can calulated and introduced into the refinement.
However, some (?) Rietveld programs can not deal with this problem, 
consequently artifacts like negative temperature factors can occur 
during refinement of data measured with automatic slits. If you are 
using such a program, recalculation of the intensities to fixed slit 
data is necessary, but this procedure may cause other problems.
I disagree that TOPAS is the only program that is able to calculate peak 
profiles and intensities of variable slits, see:

http://www.bgmn.de/vardiv.html
BGMN simulates the instrumental profile shapes by a MonteCarlo 
technique, at certain steps over 2theta. So, the profile function can be 
very well modeled.
In my personal experience, the automatic slit data can also be used for 
structure refinement, provided that they are programmed correctly. For 
phase analysis work, we always prefer ADS data.

Regards
Reinhard Kleeberg

[EMAIL PROTECTED] schrieb:


Dear Silvina,

The purpose of divergence slits is to increase the intensities of 
reflections at
high angle, the flip side is an increase in background and peak 
broadening (that

will extenuate peak overlap) at high angle.

For structural work it is best to stay with fixed slits, no 
modification needed

for the profile function  - though TOPAS (academic) is the only program
to date (I know of) that can model divergence slits.

Old school techniques of counting for longer at high angle is the best 
way to

improve stats and will not unduly effect your profile function.

Divergence slits are useful for phase identification especially if you 
are

processing a bulk number of samples. Stick with fixed slits for Rietveld
analysis.

Regards

William Bisson
CCP14 administrator
http://www.ccp14.ac.uk

Quoting Silvina Pagola [EMAIL PROTECTED]:


Hi,
I have a question regarding the use of fixed radiated length data in 
a laboratory powder diffractometer, with Bragg-Brentano geometry and 
programmable divergence and antiscatter/receiving slits, which can 
also be used in the fixed slit mode (in which the irradiated length 
on the sample varies with the theta angle).
This is, for what cases the fixed radiated lenght is recommended 
instead of fixed slits data?.
I have only these two choices for structure solution. For one 
compound I solved, it seems to work better the fixed radiated length 
data, although the background increases at high angles and I have to 
refine absorption (surface roughness), to get positive thermal 
factors. Could someone explain why to use one dataset or the other 
for structure solution and refinement?

Thanks,
Silvina.

Re: Use fix or programmable slits for Rietveld analysis

[Reinhard Kleeberg]

Hello Maria,
the main reason for using ADS is avoiding the beam-overflow at low 
angles by FDS and limited sample dimension, together with the increasing 
of the intensity at higher angles compared to FDS data. So we get more 
information at higher angles and less biased intensity at very low 
angles, provided that the ADS system is working correctly. This is 
advantageous for example in routine phase analysis, and practically 
working well if the maximum diffraction angle is limited to about 70-80 
deg 2theta, if a certain ADS divergence angle is not exceeded. In our 
experience, ADS systems with  diffracted beam monochromators can be also 
used for structure refinement, see

http://www.bgmn.de/vardiv.html
but again only up to a certain divergence angle. As Alan stated, 
deviations from the correct sin(Th) intensity relation can arise at high 
angles when the high divergence of the ADS beam can not completely reach 
the detector, mainly by cutting the diffracted beam by a narrow fixed 
antiscatter slit or by the limited dimension of the monochromator, 
starting from a certain diffraction angle.


In general, it is recommended to use untreated data in Rietveld 
refinement. Thus, the recalculation from ADS to FDS data prior to a 
Rietveld refinement is only the second choice method, necessary for 
Rietveld programs what are unable to treat the ADS data directly 
(inclusive the intensity function and profile shape dependency over 
2theta) inside of their models. That's why (i) such a recalculation 
changes the counting statistics, (ii) the intensity scaling may fail if 
any non-sample dependent background contribution like air-scatter is 
present, and (iii) the angle-dependent changes in peak shape can hardly 
be recalculated from ADS to FDS. The better solution is surely to model 
the instrumental profile shape and intensity versus 2theta by a more 
fundamental approach, for example by MonteCarlo simulation. Doing so, 
most of these biasing things like the cutting antiscatter slits can be 
treated satisfyingly, in our experience.


Reinhard Kleeberg


AlanCoelho schrieb:


Hi Maria

Automatic Divergence Slits (ADS) illuminate different parts of the post
monochromator as a function of 2Th. I am guessing but I think that the
crystals are good enough not to change the intensity too much; this is my
experience with Y2O23 in any case. 


At around 70 to 80 degrees 2Th however the beam (typically around 4 degrees
in the equatorial plane) spills out of the post monochromator. This
situation should be avoided; instead above that angle the slits should be
fixed. Thus you have the situation where part of your pattern is analysed
using ADS corrections and part using FDS corrections.

ADS corrections comprise:

- A Sin(Th) scaling of intensities
- A change in peak shape

Note, that anti scatter slits could  also influence intensities at large
divergences.

Cheers
Alan




-Original Message-
From: Fabra-Puchol, Maria [mailto:[EMAIL PROTECTED] 
Sent: Tuesday, 27 March 2007 12:03 AM

To: rietveld_l@ill.fr
Subject: Use fix or programmable slits for Rietveld analysis


Hi all,

I have a question using fix (FDS) and programmable slits (ADS) for
Rietveld analysis.
Actually, I work with a X'PERT equipment with fast detection and with
programmable divergence slits in the incident beam and a programmable
antiscattering slits in the diffracted beam.
I have also the possibility to use them in a fix mode. 
I would like to know the opinion of the community about the best

configuration of this slits (fix or programmable) if a Rietveld analysis
is required.
In fact, using programmable slits, the software corrects data and
changes from ADS to FDS. What is the interest to use ADS in this case? 


Thank you all


Maria Fabra Puchol
Microanalysis Engineer
Saint-Gobain CREE
---
550, Avenue Alphonse Jauffret
84306 Cavaillon Cedex-France
[EMAIL PROTECTED] 
telf: +33 (0)4 32 50 09 36

fax: +33 (0)4 32 50 08 51



 



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Re: Problems using TOPAS R (Rietveld refinement)

[Reinhard Kleeberg]

Dear colleagues,
sorry, my mail should go directly to Leandro, but I used this damned 
reply buttom...
My answer was related to Leandro's questions regarding these line 
broadening models. I realised that Leandro is going on to apply a 
Rietveld program for phase quantification, including kaolinite and later 
other clay minerals. I only tried to express my personal experience, 
that any inadequate profile description of a clay mineral will surely 
cause wrong QPA results, nothing else. This is a practical issue, and it 
is only partially related to structure refinement. Lubomir Smrcok is 
definitely right that other things like PO are frequently biasing a QPA 
result, but for the most of these problems working solutions do exist. 
But I disagree that anisotropic line broadening is a noble problem. In 
clay mineral mixtures, it is essentially to fit the profiles of the 
single phases as best as one can, to get any reasonable QPA result in 
a +-5 wt% interval. On the other hand, for the QPA purpose it is not so 
much important to find any sophisticated description of the 
microstructure of a phase. But the model should be flexible enough to 
cover the variablility of the profiles in a given system, and, on the 
other hand, stabil enough (not over-parametrised) to work in mixtures. 
The balancing out of these two issues could be the matter of an endless 
debate. And here I agree again, a better, more stable minimisation 
algorithm can help to keep a maximum of flexibility of the models.

Best regards
Reinhard Kleeberg

Lubomir Smrcok schrieb:


Gentlemen,
I've been listening for a week or so and I am really wondering what do you
want to get ... Actually you are setting up a refinement, whose results
will be, at least, inaccurate. I am always surprised by attempts to refine
crystal structure of a disordered sheet silicate from powders, especially
when it is known it hardly works with single crystal data. Yes, there are
several models of disorder, but who has ever proved they are really good ?
I do not mean here a graphical comparison of powder patterns with a
calculated trace, but a comparison of structure factors or integrated
intensities. (Which ones are to be selected is well described in the works
of my colleague, S.Durovic and his co-workers.)
As far as powders are concerned, all sheet silicates suffer from
prefered orientation along 001. Until you have a pattern taken in a
capillary or in transmission mode, this effect will be dominating and you
can forget such noble problems like anisotropic broadening.

Last but not least : quantitative phase analysis by Rietveld is (when only
scale factors are on) nothing else but multiple linear regression. There
is a huge volume of literature on the topic, especially which variables
must, which should and which could be a part of your model.
I really wonder why the authors of program do not add one option called
QUAN, which could, upon convergence of highly sophisticated non-linear
L-S, fix all parameters but scale factors and run standard tests or factor
analysis. One more diagonalization is not very time consuming, is it ? To
avoid numerical problems, I'd use SVD.
This idea is free and if it helps people reporting 0.1% MgO (SiO2) in a
mixture  of 10 phases to think a little of the numbers they are getting, I
would only be happy :-)
Lubo

P.S. Hereby I declare I have never used Topas and I am thus not familiar
with all its advantages or disadvantages compared to other codes.


On Wed, 21 Mar 2007, Reinhard Kleeberg wrote:

 


Dear Leandro Bravo,
some comments below:

Leandro Bravo schrieb:

   


In the refinement of chlorite minerals with well defined disordering
(layers shifting by exactly b/3 along the three pseudohexagonal Y
axis), you separate the peaks into k = 3.n (relative sharp, less
intensive peak) and k #61625; 3.n (broadened or disappeared
reflections). How did you determined this value k = 3.n and n =
0,1,2,3..., right?

 


The occurence of stacking faults along the pseudohexagonal Y axes causes
broadening of all reflections hkl with k unequal 3n (for example 110,
020, 111..) whereas the reflections with k equal 3n remain unaffected
(001, 131, 060, 331...). This is clear from geometric conditions, and
can be seen in single crystal XRD (oscillation photographs, Weissenberg
photographs) as well in selected area electron diffraction patterns. The
fact is known for a long time, and published and discussed in standard
textbooks, for example *Brindley, G.W., Brown, G.:  Crystal Structures
of Clay Minerals and their X-ray Identification. Mineralogical Society,
London, 1980.*

   


First, the chlorite refinement.

In the first refinement of chlorite you used no disordering models and
used ´´cell parameters`` and ´´occupation of octahedra``. So you
refined the lattice parameters and the occupancy of all atoms?
 


Yes, the lattice parameters.
Only the occupation/substitution of atoms with significant difference in
scattering power can be refined

Re: Problems using TOPAS R (Rietveld refinement)

[Reinhard Kleeberg]

Dear Leandro Bravo,
some comments below:

Leandro Bravo schrieb:



In the refinement of chlorite minerals with well defined disordering 
(layers shifting by exactly b/3 along the three pseudohexagonal Y 
axis), you separate the peaks into k = 3.n (relative sharp, less 
intensive peak) and k #61625; 3.n (broadened or disappeared 
reflections). How did you determined this value k = 3.n and n = 
0,1,2,3..., right?


The occurence of stacking faults along the pseudohexagonal Y axes causes 
broadening of all reflections hkl with k unequal 3n (for example 110, 
020, 111..) whereas the reflections with k equal 3n remain unaffected 
(001, 131, 060, 331...). This is clear from geometric conditions, and 
can be seen in single crystal XRD (oscillation photographs, Weissenberg 
photographs) as well in selected area electron diffraction patterns. The 
fact is known for a long time, and published and discussed in standard 
textbooks, for example *Brindley, G.W., Brown, G.:  Crystal Structures 
of Clay Minerals and their X-ray Identification. Mineralogical Society, 
London, 1980.*



First, the chlorite refinement.

In the first refinement of chlorite you used no disordering models and 
used ´´cell parameters`` and ´´occupation of octahedra``. So you 
refined the lattice parameters and the occupancy of all atoms?


Yes, the lattice parameters.
Only the occupation/substitution of atoms with significant difference in 
scattering power can be refined in powder diffraction. In case of 
chlorites, the substitution Fe-Mg at the 4 octahedral positions can be 
refined.




In the second refinement, you use na anisotropic line broadening ´´in 
the traditional way``. So you used a simple ellipsoidal model and/or 
spherical harmonics?


Simple ellipsoidal model, assuming very thiny platy crystals. But it was 
clear that this model must fail, see above the known fact of disorder in 
layer stacking. And from microscopy it is clear that the crystals are 
much too large to produce significant line broadening from size effects. 
You can see this for a lot of clay minerals: If the ellipsoidal 
crystallite shape model would be ok, the 00l reflections would have the 
broadest lines, and the 110, 020 and so on should be the sharpest ones. 
But this is not true in practice, mostly the hkl are terribly broadenend 
and smeared, but the 00l are still sharp.


The last refinement, describing a real structure. You used for the 
reflections k #61625; 3.n (broadened peaks) a ´´rod-like intensity 
distribution``, with the rod being projected by the cosine of the 
direction on the diffractogram. You used also the lenghts of the rods 
as a parameter, so as the dimension of the rods for 0k0 with k 
#61625; 3.n. I would like to know how did you ´´project`` these rods 
and use them in the refinement.


For the k = 3.n reflections, you used an anisotropic broadening model 
(aniso crystallyte size) and and isotropic broadening model 
(microstrain broadening). But you said that crystallite size is an 
isotropic line broadening in my kaolinite refinement and I should not 
use it. So I use or not the cry size?


Yes, we used an additional ellipsoidal broadening in order to describe 
any potential thinning of the crystals. But this broadening model was 
not significant because the broadening was dominated by the stacking 
faults. A microstrain makes sense because of natural chlorits are 
sometimes zoned in their chemical composition and a distribution of the 
lattice constants may occur.
In one of your mails you mentioned crysize gave reasonable numbers with 
low error, and from that I assumed you looked only on the errors of the 
isotropic crysize as defined in Topas. You must know what model you did 
apply. But it is clear that any crysize model is inadequate to 
describe the line broadening of kaolinite.



Now the kaolinite refinement.

In the first refinement was used fixed atomic positions and a 
conventional anisotropic peak broadening. This conventional 
anisotropic peak broadening would be the simple ellipsoidal model 
and/or spherical harmonics?!


Only ellipsoidal model, assuming a platy crystal shape, see above. Only 
for comparision.




After that you use the introduced model of disorfering. Is this model 
the same of the chlorite (rods for k #61625; 3.n and microstrain 
broadening and anisotropic crystallite size?


Not exactly the same like in chlorite, because the disorder in kaolinite 
is much more complicated like in chlorites. See also the textbook cited 
above, and extensive works of Plancon and Tchoubar. Thus, most of the 
natural kaolinites show stacking faults along b/3 as well as along a, 
and additional random faults. Thus, more broadening parameters had to be 
defined, and this is not completely perfect until now. See the 
presentation I sent you last week.


Best regards

Reinhard Kleeberg
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Re: Problems using TOPAS R (Rietveld refinement)

[Reinhard Kleeberg]

Dear Leandro,
some comments:
Leandro Bravo schrieb:

I know that refining the atoms positions is ´´too much´´, exagerated. 
But is the only way I can make the calculated DRX pattern fit with the 
measured one. There must a problem in the instrument details since I´m 
using Fundamental Parameters (FP) for peak shape, the values I put in 
the instrument description play a major role in FP, am I right?


No. The misfit in your Rietveld refinement of kaolinite you get by using 
published atomic coordinates and temperature factors does definitely not 
arise from wrong published structure date and probably not significantly 
from any error in your instrumental parameters.  Kaolinite diffraction 
pattern can not be described by simple isotropic line broadening as you 
tried by the crystallite size parameter. The different types and 
amounts of stacking faults in kaolinite are the reason for different 
kinds of smearing of the reciprocal lattice points. It makes no sense 
to refine atomic coordinates and temperature factors in an ideal cell to 
get a better Rwp of a disordered structure: One will of course get a 
better fit, but this is reached by variations of intensity by 
meaningless atomic positions.


I made a new scan, of the same sample, with range from 10° to 80°, 
step size 0,02 and count time 4 seconds. The old one was from 5° to 
120,° maybe it is prejudicing the background refining.


Tomorrow I´m gonna to scrap this old pattern and work with the new 
one. I´m having a good response refining the calcite and teh dolomite 
in the sample only refining lattice parameters, cry size and beq. I 
think that refining this is what we can call a ´´normal refining 
method``. Now the kaolinite...


The major problem is that I have a sample from a laterite with 
hydroxyapatite, calcite, dolomite, vermiculite and other phases. The 
vermiculite is very alterated and in the DRX pattern we can confuse it 
with other ``layered silicates``, it will be a huge problem. But I 
will only put my hands on these samples after finishing with the 
kaolinite. 


Altered vermiculite is probably a mixed-layered clay mineral? If yes, 
I'm in doubt that you can quantify this by the Rietveld method. See:


Omotoso, O., McCarty, D.K., Hillier, S., Kleeberg, R. (2006) Some 
successful approaches to quantitative mineral analysis as revealed by 
the 3^rd Reynolds Cup contest. Clays and Clay Minerals, 54 (6),  751-763.


One question, these ´´models`` and ´´trials`` that you talk about 
regarding the kaolinite is used in the CIF part of the refinement, am 
I right?! It´s not a part of the TOPAS itself. right?


I think he CIF part you are referring is from the database you used 
(ICSD), right? These data refer to the ideal cell. One must introduce 
any models regarding line broadening or supercell coordinates into your 
structure model (*.str ?) what is used in your refinement. You will not 
find such models in a crystallographic database, specific formulations 
are necessary, depending on your disorder problem and on the 
capabilities of your Rietveld program. 
Best regards


Reinhard



Thank you,

Leandro

_
Chegou o Windows Live Spaces com rede social. Confira 
http://spaces.live.com/




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Re: McCrone Micronizing Mill Users - New Style Corundum Elements

[Reinhard Kleeberg]

Yes, the problem was already reported by some colleagues in Germany and 
the US as well. These customers did reclaim, but I don't know the 
answers of the company. It is obvious that McCrone Ltd needs a new 
supplier for more densely sintered corundum ceramics.

Reinhard Kleeberg

Mati Raudsepp schrieb:



We have been using the McCrone Micronizing mill for many years with 
the pink corundum grinding elements with good results. Generally, 
contamination from the grinder ranged from not detectable to a maximum 
of 1-3 wt.% depending on the  specimen. Most of the material we grind 
is quartz/feldspar rich rock. Recently we got the new style elements 
which are white, not as well finished and look slightly porous 
relative to the old elements. Regrinding old specimens as a check now 
gives about 7-10 wt.% contamination from the elements. McCrone admits 
having complaints about the new elements but I have not had a chance 
to follow up to see if there is a solution.


Have any of you McCrone users found the same problem with the new 
white elements?



Mati Raudsepp, Professor (Hon.)
Director:  Electron-microbeam/X-ray Diffraction Laboratory
Department of Earth  Ocean Sciences
6339 Stores Road
The University of British Columbia
Vancouver, BC  V6T 1Z4

Tel:   604-822-6396
Fax:  604-822-6088



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title:Dr.
tel;work:(+49) (0)3731 393244
tel;fax:(+49)(0)3731 393129
url:http://www.mineral.tu-freiberg.de/mineralogie/roelabor/
version:2.1
end:vcard

SPAM via our list

[Reinhard Kleeberg]

Hello all,
actually we get some mails with German subjects to our list. These are
spams with links to sites with rassistic or neo-nazi content, generated by
a worm sober.p or so.
Beschreibung: W32.Sober.P alias Trojan.Ascetic.C
see http://www.heise.de/security/artikel/59580
Would be great if anyone who found his address as sender would check his
computer for the worm, to reduce this trash.

Reinhard Kleeberg

At 23:11 17.05.2005 GMT, you wrote:
und weisst es nicht einmal:


Dr. R. Kleeberg
TU Bergakademie Freiberg
Institut für Mineralogie
Brennhausgasse 14
D-09596 Freiberg
Germany
Tel. +49 (0) 3731-39-3244
Fax. +49 (0) 3731-39-3129

Re: SPAM via our list

[Reinhard Kleeberg]

Sorry Vincent,
you are right, I did not read carefully the article . There seems to be no
chance to clean the list by asking the misused senders.
Sorry again
Reinhard

At 10:14 18.05.2005 +0200, you wrote:
 actually we get some mails with German subjects to our list. These are
 spams with links to sites with rassistic or neo-nazi content, generated by
 a worm sober.p or so.
 Beschreibung: W32.Sober.P alias Trojan.Ascetic.C
 see http://www.heise.de/security/artikel/59580
 Would be great if anyone who found his address as sender would check his
 computer for the worm, to reduce this trash.

   This is useless. The email adress of the sender if always *forged*, and 
will *not* correspond to the computer from which the email originates. So no 
need to bother the person whose adress has been used.
   This is actually described @ http://www.heise.de/security/artikel/59580, 
near the middle of the page:


Von: Absender gefälscht


English translation: From: Sender falsified

-- 
Vincent Favre-Nicolin
Université Joseph Fourier
http://v.favrenicolin.free.fr
ObjCryst  Fox : http://objcryst.sourceforge.net

Dr. R. Kleeberg
TU Bergakademie Freiberg
Institut für Mineralogie
Brennhausgasse 14
D-09596 Freiberg
Germany
Tel. +49 (0) 3731-39-3244
Fax. +49 (0) 3731-39-3129

Colloquium Microstructure Analysis in the Materials Science

[Reinhard Kleeberg]

Dear colleagues,
the program of the Freiberg colloquium

Microstructure Analysis in the Materials Science

is available at
http://www.ww.tu-freiberg.de/mk/bht/

registration at

http://www.tu-freiberg.de/allgemein/presse/aktuell/bht2005/karten.html 

Regards
R. Kleeberg

Dr. R. Kleeberg
TU Bergakademie Freiberg
Institut für Mineralogie
Brennhausgasse 14
D-09596 Freiberg
Germany
Tel. +49 (0) 3731-39-3244
Fax. +49 (0) 3731-39-3129

modelling turbostratically disorded clays

[Reinhard Kleeberg]

Dear Rietvelders,
if you are interested in analyzing clay-bearing samples, you can find an
idea at 

http://www.bgmn.de/smectite.html

The text of the structure description files *.str can be used in BGMN
directly. People who would like to adapt this approach to other programs
can find some helpful comments in these files. 

Reinhard Kleeberg
Dr. R. Kleeberg
TU Bergakademie Freiberg
Institut für Mineralogie
Brennhausgasse 14
D-09596 Freiberg
Germany
Tel. +49 (0) 3731-39-3244
Fax. +49 (0) 3731-39-3129

Second Reynolds Cup - information available

[Reinhard Kleeberg]

Dear Rietvelders,
you can find some information about the Second Reynolds Cup in quantitative
phase analysis at:

http://www.dttg.ethz.ch/thereynoldscup.html

More details like the powder patterns of the reference minerals and the
mixtures can be requested from the author.

Thanks again to all participants for their efforts in improving the methods
of phase analysis.

Best regards

Reinhard Kleeberg
Dr. R. Kleeberg
TU Bergakademie Freiberg
Institut für Mineralogie
Brennhausgasse 14
D-09596 Freiberg
Germany
Tel. +49 (0) 3731-39-3244
Fax. +49 (0) 3731-39-3129

Re: fundamental parameters approach

[Reinhard Kleeberg]

Hi Jon and Pamela,
my very personal opinion regarding the fundamental parameter stuff:
- fundamental is that the observed peak shape is a folding of contributions
from (i) wavelength distribution, (ii) instrumental/geometrical aberations
and (iii) microstructure of the sample. From this point of view all
programs keeping constant (i) and (ii) and refining only a model for (iii)
do use a FP approach.
- The fundamental parameters in profile modelling could be defined as the
sample independent or fixed contributions to the profile shape, for
example the wavelength distribution function, slit widths/divergencies,
distances, sample dimensions... So a program that uses such values for the
calculation of (i) and especially (ii) could be called FPA program in
sensu strictu. This is true for Topas if the full axial model is chosen
and for BGMN if the raytracing simulation is used. 
- each fundamental parameter approach contains, of course, a model,
(sometimes an oversimplificated one).
- refining of fundamental parameters is nonsense, unless one is not
familiar with his diffractometer or want/must absorb any unkown effects
or weaknesses of his model :-)
- The main advantage of the fundamental parameter approach (in comparison
to learnt profiles) is that no standard measurement is required and that
the whole angular range can be described without extrapolations.
- Jon, I agree completely: any model what is able to describe adequately
the profile shapes caused by the device INDEPENDENTLY of the
microstructural broadening is a priori the better choice than a together
fitting of any dubious parameters of physically meaningless analytical
functions.
- Pamela, there are surely additional reasons (besides the FPA peak shape
modelling) for the high stability and the easy use of the programs like
BGMN and Topas in comparision to traditional DBWS and similar codes: a more
stable minimization algorithm, the extensive and easy use of
restraints/constraints...

Reinhard


At 15:11 04.06.2004 +0200, you wrote:

Is the fundamental parameter approach better than
mathematical approach used in most of the Rietveld
refinement programs? 

Perhaps someone is about to explain the difference is between 
fundamental parameters and anything else? I used to think it might 
mean convoluting something which was actually measured into the 
peakshape description, but this doesn't always seem to be the case? I'm 
guessing it has to be more than choosing suitable equations for peak 
width parameters and peak positions as a function of scattering 
variable, otherwise all programs are using fundamental parameters 
already, just some are better approximations for certain diffractometers 
than others.

In any case, if the calculated peakshape matches the observed peakshape 
then it makes no difference for refinement of a crystal structure. For 
deriving microstructural parameters, like size and strain, then a 
better description of the instrument can help, and can be a good 
indicator of diffractometer misalignment. In that sense, zero shift is a 
fundamental parameter, but does not seem to be unique to fundamental 
parameters programs. Perhaps the difference is that programs which 
don't do fundamental parameters make you compute size and strain 
from the peakshape parameters yourself.

Jon

Dr. R. Kleeberg
TU Bergakademie Freiberg
Institut für Mineralogie
Brennhausgasse 14
D-09596 Freiberg
Germany
Tel. +49 (0) 3731-39-3244
Fax. +49 (0) 3731-39-3129

RE: fundamental parameters approach

[Reinhard Kleeberg]

Pamela,
At 10:24 07.06.2004 -0400, you wrote:
In a perfect world this would be the case, but given that very few people
run systems that conform to the requirements for true fundamental parameters
(Bragg-Brentano with NO monochromator, mirrors, etc), then one is not really
using fundamental parameters per se, which is why using the term
convolution-based profile fitting is a better terminology.  

sounds like a reasonable definition. 

Some of the
effects of things like monochromators are amenable to modelling - they act
in the same way as a Soller slit, as well as having a slight effect on the
radiation characteristics reaching the detector.

At least for standard diffractometers equipped with secondary beam
pyrolitic graphite monochromators we did never observe such problems. You
are right for single crystal monochromators (they cut the wavelength
distribution profile in the feets), and of course for mirrors having
unknown divergence and sometimes a dubious lateral intensity distribution.
But what is a parameter to be refined in such a case? Any virtual
divergence? This sounds a little bit empiric.

In the case of the conventional
Bragg-Brentano, these functions are known, and their dependence on the
geometry known.  For other systems is it a good start, but other, user
defined functions (or modifications of the existing ones) may be necessary
to correctly model the instrument function, which, at the end of the day is
what you need.

O.K., this is really learning the instrumental function by fitting of
empirical parameters. 


I don't know if you've any experience with them, but if you can model the
effects of two mirrors on the profiles of a system (including minor errors
in alignment in both) then you are a better person than I.  

 We never tried to invent any divergencies of these optics. But we tried
to get the geometric profile by learning from a standard for a D5000 with
2 Goebel mirrors (http://www.bgmn.de/learnt.html) and also for another
device using a position sensitive detector. No problem to get the
instrumental profile, but a high quality standard measurement is necessary.
And this must done again after realignement ... :-)

This is true - I don't know about BGMN, but Topas has a very stable
algorithm.  However, Topas will also use more conventional profile
characteristics, and can suffer from some similar and some different
problems from conventional programs. I have been a long time user of GSAS
and appreciate the stability of Topas, but one must be careful to make sure
the parameters make sense at the end of the day.  Only having one or two
variables in the profile shape is a constraint in itself, additionally
contributing to a stable refinement in complex systems.  


Absolutely, this is the same deep impression I got when I was coming from
DBWS to BGMN. The program ALWAYS converges. But the choice of a reasonable
model stays the task of the user.

Reinhard
Dr. R. Kleeberg
TU Bergakademie Freiberg
Institut für Mineralogie
Brennhausgasse 14
D-09596 Freiberg
Germany
Tel. +49 (0) 3731-39-3244
Fax. +49 (0) 3731-39-3129