RE: Quantitative analysis

[Matthew.Rowles]

Hi Blaise

In Bragg-Brentano mode, sample spinning does nothin for PO. This is because the 
diffraction vector is normal to the sample surface, and sample spinning rotates 
along this vector.

Spinning does increase your particle statistics, which almost always helps.


If you're looking at a capillary, spinning the capillary does help with PO, but 
just being in a capillary helps PO.


As to spinning speeds, a good guide is one revolution per data point.




Cheers

Matthew


Matthew Rowles

CSIRO Minerals
Box 312
Clayton South, Victoria
AUSTRALIA 3169

Ph: +61 3 9545 8892
Fax: +61 3 9562 8919 (site)
Email: [EMAIL PROTECTED]




From: Mibeck, Blaise [mailto:[EMAIL PROTECTED]
Sent: Wednesday, 29 October 2008 01:25
To: rietveld_l@ill.fr
Subject: RE: Quantitative analysis


I am learning QPA and am worried about PO.

I wonder why sample spinning isn't discussed more.

I am luckily able to barrow time on a newer diffractometer with a sample 
spinner.

Does this reduce PO? Or completely eliminate it? There is a set up variable in 
GSAS for whether you are spinning the sample - are there guidelines for how 
many revolutions to spin the sample if you just want to reduce PO?

Thanks to all for there help!!!
Blaise




* * * * * * * * * * * * *
Blaise Mibeck
Research Scientist
Energy & Environmental Research Center
University of North Dakota
15 North 23rd Street, Stop 9018
Grand Forks, ND 58202-9018

Phone: (701) 777-5077
Email: [EMAIL PROTECTED]


-Original Message-
From: David L. Bish [mailto:[EMAIL PROTECTED]
Sent: Tuesday, October 28, 2008 9:09 AM
To: Martin; [EMAIL PROTECTED]; rietveld_l@ill.fr
Subject: RE: Quantitative analysis

I agree that it's always best to avoid preferred orientation, but that is 
easier said than done on a routine basis.  I have personally had good luck with 
the M-D PO correction on many known samples, as long as the PO was not severe.

However, I imagine that Mario's problems are related to microabsorption in this 
case.  Mario, if you can re-measure your data with a Co or Fe tube, it would be 
a good test of this.

Dave Bish

At 08:51 AM 10/28/2008 -0400, Martin wrote:

Sorry to disagree. Experience tells me otherwise - the March-Dollase correction 
has nearly always led to poor quant results for me. It most certainly cannot be 
applied safely.

Martin

--

M Vickers
Dept of Chemistry
UCL



> Subject: Re: Quantitative analysis
> Date: Tue, 28 Oct 2008 02:53:20 -0700
> From: [EMAIL PROTECTED]
> To: Rietveld_l@ill.fr
>
> Dear Mario,
>
> One more possible problem of applying preferred orientation corrections in 
> QPA is that not all of them are normalized. For example, the March-Dollase 
> correction is normalized and can be applied safely, but the Rietveld-Toraya 
> correction is inapplicable to QPA as it does not preserve the scale 
> normalization.
>
> Best regards,
> Leonid
>
> ***
> Leonid A. Solovyov
> Institute of Chemistry and Chemical Technology
> K. Marx av., 42
> 660049, Krasnoyarsk Russia
> Phone: +7 3912 495663
> Fax: +7 3912 238658
> www.icct.ru/eng/content/persons/Sol_LA
>

For the best free wallpapers from MSN Click 
here!

RE: Quantitative analysis

[Martin]

Spinning the sample doesn't reduce preferred orientation much. It does, 
however, improve ones counting statistics very nicely.
 
Martin 
 

M Vickers
Dept. of Chemistry
UCL
20, Gordon Street
London
WC1E 0HX



Subject: RE: Quantitative analysisDate: Tue, 28 Oct 2008 09:25:13 -0500From: 
[EMAIL PROTECTED]: rietveld_l@ill.fr




 
I am learning QPA and am worried about PO. 
 
I wonder why sample spinning isn’t discussed more. 
 
I am luckily able to barrow time on a newer diffractometer with a sample 
spinner. 
 
Does this reduce PO? Or completely eliminate it? There is a set up variable in 
GSAS for whether you are spinning the sample – are there guidelines for how 
many revolutions to spin the sample if you just want to reduce PO?
 
Thanks to all for there help!!!
Blaise
 
 
 
 

* * * * * * * * * * * * * 
Blaise Mibeck 
Research Scientist
Energy & Environmental Research Center
University of North Dakota
15 North 23rd Street, Stop 9018
Grand Forks, ND 58202-9018
 
Phone: (701) 777-5077
Email: [EMAIL PROTECTED]
_
Discover Bird's Eye View now with Multimap from Live Search
http://clk.atdmt.com/UKM/go/111354026/direct/01/

RE: Quantitative analysis

[mariomacias]

Thank you to all for your generous help... has been very important your
information..

Mario.



Mario,
>
> From the information that you just gave, it appears that the corundum 012
> and siderite 012 are not well resolved causing more of the siderite 012
> intensity to be attributed to the corundum 012 and an overestimation of
> corundum.  If it is a microabsorption problem, you wouldn't get a good QPA
> data without PO correction to start with. If you can, reduce the receiving
> slit size and run the sample again or don't correct for PO.
>
> Dipo Omotoso
>
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Sent: October 28, 2008 8:24 AM
> To: Rietveld_l@ill.fr
> Subject: RE: Quantitative analysis
>
>>Dear all,
>
> the well-known data are: CaCO3 (20%), CaF2 (35%), SiO2 (1%), Al2O3 (20%),
> and FeCO3 (24%). The data obtained without PO are: CaCO3 (24%), CaF2
> (36%), SiO2 (1%), Al2O3 (17%), and FeCO3 (23%). The data obtained with PO
> are: CaCO3 (19%), CaF2 (32%), SiO2 (2%), Al2O3 (31%), and FeCO3 (16%).
> it seems to have a problem among Al2O3 and FeCO3 data after PO.
>
> Mario.
>
>
>  Dear all,
>>
>> The data collection conditions is: hand grind (35 microns), scan:
>> 2Theta/Theta Coupled, to steps 2 sec., target Cu, graphite
>> monochromator, side loading. The correction of preferential
>> orientation has been refined by March-Dollase model.
>>
>> Thanks a lot,
>>
>> Mario.
>>
>>
>>
>>
>> Dear Mario,
>>>
>>> Please tell me a little about the data collection conditions you used
>>> for this work:-
>>>
>>> How was the sample prepared (hand ground, micronised in McCrone mill
>>> )
>>> What was the tube target Cu, Co, other ??
>>>
>>> Cheers
>>> Ian Madsen
>>> 
>>> From: [EMAIL PROTECTED] [EMAIL PROTECTED]
>>> Sent: Tuesday, October 28, 2008 2:48 AM
>>> To: Rietveld_l@ill.fr
>>> Subject: Quantitative analysis
>>>
>>> Dear all,
>>>
>>> I have this question,
>>>
>>> I have been refined one mixture (of well-know percentage composition)
>>> of CaCO3, CaF2, SiO2 and Al2O3, with preferential orientation in
>>> CaCO3
>>> (104)
>>> and CaF2 (111) with good results. When I add to the mixture FeCO3 and
>>> I refine with preferential orientation (104), it happens that when I
>>> don´t apply the preferential orientation in all this phases, I have
>>> correct values of percentage composition, but when I apply the
>>> preferential orientation the refinement is good but with incorrect
>>> values of percentage composition. This experiment has been taken in
>>> Bragg Brentano geometry.
>>> How I should refine this mixture?
>>>
>>> Thanks a lot by your help.
>>>
>>> Mario Macías
>>> Universidad Industrial de Santander
>>> Colombia
>>>
>>>
>>
>>
>>
>>
>
>
>
>
>

RE: Quantitative analysis

[Omotoso, Oladipo]

Mario,

>From the information that you just gave, it appears that the corundum 012 and 
>siderite 012 are not well resolved causing more of the siderite 012 intensity 
>to be attributed to the corundum 012 and an overestimation of corundum.  If it 
>is a microabsorption problem, you wouldn't get a good QPA data without PO 
>correction to start with. If you can, reduce the receiving slit size and run 
>the sample again or don't correct for PO.

Dipo Omotoso   

-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] 
Sent: October 28, 2008 8:24 AM
To: Rietveld_l@ill.fr
Subject: RE: Quantitative analysis

>Dear all,

the well-known data are: CaCO3 (20%), CaF2 (35%), SiO2 (1%), Al2O3 (20%), and 
FeCO3 (24%). The data obtained without PO are: CaCO3 (24%), CaF2 (36%), SiO2 
(1%), Al2O3 (17%), and FeCO3 (23%). The data obtained with PO
are: CaCO3 (19%), CaF2 (32%), SiO2 (2%), Al2O3 (31%), and FeCO3 (16%).
it seems to have a problem among Al2O3 and FeCO3 data after PO.

Mario.


 Dear all,
>
> The data collection conditions is: hand grind (35 microns), scan:
> 2Theta/Theta Coupled, to steps 2 sec., target Cu, graphite 
> monochromator, side loading. The correction of preferential 
> orientation has been refined by March-Dollase model.
>
> Thanks a lot,
>
> Mario.
>
>
>
>
> Dear Mario,
>>
>> Please tell me a little about the data collection conditions you used 
>> for this work:-
>>
>> How was the sample prepared (hand ground, micronised in McCrone mill
>> )
>> What was the tube target Cu, Co, other ??
>>
>> Cheers
>> Ian Madsen
>> 
>> From: [EMAIL PROTECTED] [EMAIL PROTECTED]
>> Sent: Tuesday, October 28, 2008 2:48 AM
>> To: Rietveld_l@ill.fr
>> Subject: Quantitative analysis
>>
>> Dear all,
>>
>> I have this question,
>>
>> I have been refined one mixture (of well-know percentage composition) 
>> of CaCO3, CaF2, SiO2 and Al2O3, with preferential orientation in 
>> CaCO3
>> (104)
>> and CaF2 (111) with good results. When I add to the mixture FeCO3 and 
>> I refine with preferential orientation (104), it happens that when I 
>> don´t apply the preferential orientation in all this phases, I have 
>> correct values of percentage composition, but when I apply the 
>> preferential orientation the refinement is good but with incorrect 
>> values of percentage composition. This experiment has been taken in 
>> Bragg Brentano geometry.
>> How I should refine this mixture?
>>
>> Thanks a lot by your help.
>>
>> Mario Macías
>> Universidad Industrial de Santander
>> Colombia
>>
>>
>
>
>
>

Re: Quantitative analysis

[Radovan Cerny]

The empirical PO corrections like March-Dollase or Rietveld-Toraya can 
correct only for fibre like PO, i.e. symmetrical around one axis. If it 
is not your case, you can make it fibre like by spinning, if you spin 
around the PO vector. If not than see J. Appl. Cryst. 28(1995)247-253.


However, there are few other limitations, which are usually completly 
ignored:


The distribution of crystallites around any pole hkl must be axially 
symmetrical either, so-called disc- or rod-shape like behavior. No way 
to do it by spinning ...


Most of implementations of these corrections in the Rietveld codes also 
assume another condition: The texture axis is parallel (or 
perpendicular) to the diffraction vector for all measured hkls. This 
condition is fullfilled only in Bragg-Brentano or Debye-Scherrer geometries.


Surprising that it still works ...


Radovan


Mibeck, Blaise a écrit :
 


I am learning QPA and am worried about PO.

 


I wonder why sample spinning isn’t discussed more.

 

I am luckily able to barrow time on a newer diffractometer with a sample 
spinner.


 

Does this reduce PO? Or completely eliminate it? There is a set up 
variable in GSAS for whether you are spinning the sample – are there 
guidelines for how many revolutions to spin the sample if you just want 
to reduce PO?


 


Thanks to all for there help!!!

Blaise

 

 

 

 


* * * * * * * * * * * * *

Blaise Mibeck

Research Scientist

Energy & Environmental Research Center

University of North Dakota

15 North 23rd Street, Stop 9018

Grand Forks, ND 58202-9018

 


Phone: (701) 777-5077

Email: [EMAIL PROTECTED] 

 

 


-Original Message-
*From:* David L. Bish [mailto:[EMAIL PROTECTED]
*Sent:* Tuesday, October 28, 2008 9:09 AM
*To:* Martin; [EMAIL PROTECTED]; rietveld_l@ill.fr
*Subject:* RE: Quantitative analysis

 

I agree that it's always best to avoid preferred orientation, but that 
is easier said than done on a routine basis.  I have personally had good 
luck with the M-D PO correction on many known samples, as long as the PO 
was not severe.


However, I imagine that Mario's problems are related to microabsorption 
in this case.  Mario, if you can re-measure your data with a Co or Fe 
tube, it would be a good test of this.


Dave Bish

At 08:51 AM 10/28/2008 -0400, Martin wrote:

Sorry to disagree. Experience tells me otherwise - the March-Dollase 
correction has nearly always led to poor quant results for me. It most 
certainly cannot be applied safely.
 
Martin
 
--
 
M Vickers

Dept of Chemistry
UCL





 Subject: Re: Quantitative analysis
 Date: Tue, 28 Oct 2008 02:53:20 -0700
 From: [EMAIL PROTECTED]
 To: Rietveld_l@ill.fr

 Dear Mario,

 One more possible problem of applying preferred orientation 
corrections in QPA is that not all of them are normalized. For example, 
the March-Dollase correction is normalized and can be applied safely, 
but the Rietveld-Toraya correction is inapplicable to QPA as it does not 
preserve the scale normalization.


 Best regards,
 Leonid

 ***
 Leonid A. Solovyov
 Institute of Chemistry and Chemical Technology
 K. Marx av., 42
 660049, Krasnoyarsk Russia
 Phone: +7 3912 495663
 Fax: +7 3912 238658
 www.icct.ru/eng/content/persons/Sol_LA 








For the best free wallpapers from MSN Click here! 






--
Radovan Cerny
Laboratoire de Cristallographie
24, quai Ernest-Ansermet
CH-1211 Geneva 4, Switzerland
Phone  : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08
mailto : [EMAIL PROTECTED]
URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm

RE: Quantitative analysis

[Mibeck, Blaise]

 

I am learning QPA and am worried about PO. 

 

I wonder why sample spinning isn't discussed more. 

 

I am luckily able to barrow time on a newer diffractometer with a sample
spinner. 

 

Does this reduce PO? Or completely eliminate it? There is a set up
variable in GSAS for whether you are spinning the sample - are there
guidelines for how many revolutions to spin the sample if you just want
to reduce PO?

 

Thanks to all for there help!!!

Blaise

 

 

 

 

* * * * * * * * * * * * * 

Blaise Mibeck 

Research Scientist

Energy & Environmental Research Center

University of North Dakota

15 North 23rd Street, Stop 9018

Grand Forks, ND 58202-9018

 

Phone: (701) 777-5077

Email: [EMAIL PROTECTED]

 

 

-Original Message-
From: David L. Bish [mailto:[EMAIL PROTECTED] 
Sent: Tuesday, October 28, 2008 9:09 AM
To: Martin; [EMAIL PROTECTED]; rietveld_l@ill.fr
Subject: RE: Quantitative analysis

 

I agree that it's always best to avoid preferred orientation, but that
is easier said than done on a routine basis.  I have personally had good
luck with the M-D PO correction on many known samples, as long as the PO
was not severe.

However, I imagine that Mario's problems are related to microabsorption
in this case.  Mario, if you can re-measure your data with a Co or Fe
tube, it would be a good test of this.

Dave Bish

At 08:51 AM 10/28/2008 -0400, Martin wrote:



Sorry to disagree. Experience tells me otherwise - the March-Dollase
correction has nearly always led to poor quant results for me. It most
certainly cannot be applied safely.
 
Martin
 
--
 
M Vickers
Dept of Chemistry
UCL






> Subject: Re: Quantitative analysis
> Date: Tue, 28 Oct 2008 02:53:20 -0700
> From: [EMAIL PROTECTED]
> To: Rietveld_l@ill.fr
> 
> Dear Mario,
> 
> One more possible problem of applying preferred orientation
corrections in QPA is that not all of them are normalized. For example,
the March-Dollase correction is normalized and can be applied safely,
but the Rietveld-Toraya correction is inapplicable to QPA as it does not
preserve the scale normalization. 
> 
> Best regards,
> Leonid
> 
> ***
> Leonid A. Solovyov
> Institute of Chemistry and Chemical Technology
> K. Marx av., 42
> 660049, Krasnoyarsk Russia
> Phone: +7 3912 495663
> Fax: +7 3912 238658
> www.icct.ru/eng/content/persons/Sol_LA
> 



For the best free wallpapers from MSN Click here!
  

RE: Quantitative analysis

[mariomacias]

>Dear all,

the well-known data are: CaCO3 (20%), CaF2 (35%), SiO2 (1%), Al2O3 (20%),
and FeCO3 (24%). The data obtained without PO are: CaCO3 (24%), CaF2
(36%), SiO2 (1%), Al2O3 (17%), and FeCO3 (23%). The data obtained with PO
are: CaCO3 (19%), CaF2 (32%), SiO2 (2%), Al2O3 (31%), and FeCO3 (16%).
it seems to have a problem among Al2O3 and FeCO3 data after PO.

Mario.


 Dear all,
>
> The data collection conditions is: hand grind (35 microns), scan:
> 2Theta/Theta Coupled, to steps 2 sec., target Cu, graphite monochromator,
> side loading. The correction of preferential orientation has been refined
> by March-Dollase model.
>
> Thanks a lot,
>
> Mario.
>
>
>
>
> Dear Mario,
>>
>> Please tell me a little about the data collection conditions you used
>> for
>> this work:-
>>
>> How was the sample prepared (hand ground, micronised in McCrone mill
>> )
>> What was the tube target Cu, Co, other ??
>>
>> Cheers
>> Ian Madsen
>> 
>> From: [EMAIL PROTECTED] [EMAIL PROTECTED]
>> Sent: Tuesday, October 28, 2008 2:48 AM
>> To: Rietveld_l@ill.fr
>> Subject: Quantitative analysis
>>
>> Dear all,
>>
>> I have this question,
>>
>> I have been refined one mixture (of well-know percentage composition) of
>> CaCO3, CaF2, SiO2 and Al2O3, with preferential orientation in CaCO3
>> (104)
>> and CaF2 (111) with good results. When I add to the mixture FeCO3 and I
>> refine with preferential orientation (104), it happens that when I don´t
>> apply the preferential orientation in all this phases, I have correct
>> values of percentage composition, but when I apply the preferential
>> orientation the refinement is good but with incorrect values of
>> percentage
>> composition. This experiment has been taken in Bragg Brentano geometry.
>> How I should refine this mixture?
>>
>> Thanks a lot by your help.
>>
>> Mario Macías
>> Universidad Industrial de Santander
>> Colombia
>>
>>
>
>
>
>

RE: Quantitative analysis

[David L. Bish]

I agree that it's always best to avoid preferred orientation, but that is 
easier said than done on a routine basis.  I have personally had good luck 
with the M-D PO correction on many known samples, as long as the PO was not 
severe.


However, I imagine that Mario's problems are related to microabsorption in 
this case.  Mario, if you can re-measure your data with a Co or Fe tube, it 
would be a good test of this.


Dave Bish

At 08:51 AM 10/28/2008 -0400, Martin wrote:
Sorry to disagree. Experience tells me otherwise - the March-Dollase 
correction has nearly always led to poor quant results for me. It most 
certainly cannot be applied safely.


Martin

--

M Vickers
Dept of Chemistry
UCL



--

> Subject: Re: Quantitative analysis
> Date: Tue, 28 Oct 2008 02:53:20 -0700
> From: [EMAIL PROTECTED]
> To: Rietveld_l@ill.fr
>
> Dear Mario,
>
> One more possible problem of applying preferred orientation corrections 
in QPA is that not all of them are normalized. For example, the 
March-Dollase correction is normalized and can be applied safely, but the 
Rietveld-Toraya correction is inapplicable to QPA as it does not preserve 
the scale normalization.

>
> Best regards,
> Leonid
>
> ***
> Leonid A. Solovyov
> Institute of Chemistry and Chemical Technology
> K. Marx av., 42
> 660049, Krasnoyarsk Russia
> Phone: +7 3912 495663
> Fax: +7 3912 238658
> www.icct.ru/eng/content/persons/Sol_LA
>


--
For the best free wallpapers from MSN Click here!

RE: Quantitative analysis

[Whitfield, Pamela]

While my coffee pot gurgles away here's my tuppence worth

As mentioned by previous answers prevention is MUCH better than cure.

Having said that a couple of comments.  If there's significant PO then it's a 
pretty sure thing that the particles are not spherical - so you can forget the 
Brindley correction which assumes spherical (and also monodisperse BTW) 
particles.  PO is also strongly suggestive (but not certain) of fairly large 
particles, so microabsorption could be pretty severe. In this case with FeCO3 
and Cu radiation microabsorption is going to be an issue independent of whether 
the PO correction preserves the scale normalization.

Pam


Dr Pamela Whitfield MRSC CChem
Energy Materials
Institute for Chemical Process and Environmental Technology (ICPET)
Building M12
National Research Council Canada
1200 Montreal Road
Ottawa  ON  K1A 0R6
CANADA

Tel: (613) 998-8462Fax: (613) 991 2384
Email: [EMAIL PROTECTED]



-Original Message-
From: Leonid Solovyov [mailto:[EMAIL PROTECTED] 
Sent: October 28, 2008 5:53 AM
To: Rietveld_l@ill.fr
Subject: Re: Quantitative analysis

Dear Mario,

One more possible problem of applying preferred orientation corrections in QPA 
is that not all of them are normalized. For example, the March-Dollase 
correction is normalized and can be applied safely, but the Rietveld-Toraya 
correction is inapplicable to QPA as it does not preserve the scale 
normalization. 

Best regards,
Leonid

***
Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
K. Marx av., 42
660049, Krasnoyarsk  Russia
Phone: +7 3912 495663
Fax:   +7 3912 238658
www.icct.ru/eng/content/persons/Sol_LA
***

--- On Mon, 10/27/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:

> From: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
> Subject: Quantitative analysis
> To: Rietveld_l@ill.fr
> Date: Monday, October 27, 2008, 3:48 PM
> Dear all,
> 
> I have this question,
> 
> I have been refined one mixture (of well-know percentage
> composition) of
> CaCO3, CaF2, SiO2 and Al2O3, with preferential orientation
> in CaCO3 (104)
> and CaF2 (111) with good results. When I add to the mixture
> FeCO3 and I
> refine with preferential orientation (104), it happens that
> when I don´t
> apply the preferential orientation in all this phases, I
> have correct
> values of percentage composition, but when I apply the
> preferential
> orientation the refinement is good but with incorrect
> values of percentage
> composition. This experiment has been taken in Bragg
> Brentano geometry.
> How I should refine this mixture?
> 
> Thanks a lot by your help.
> 
> Mario Macías
> Universidad Industrial de Santander
> Colombia


  

RE: Quantitative analysis

[mariomacias]

Dear all,

The data collection conditions is: hand grind (35 microns), scan:
2Theta/Theta Coupled, to steps 2 sec., target Cu, graphite monochromator,
side loading. The correction of preferential orientation has been refined
by March-Dollase model.

Thanks a lot,

Mario.




Dear Mario,
>
> Please tell me a little about the data collection conditions you used for
> this work:-
>
> How was the sample prepared (hand ground, micronised in McCrone mill )
> What was the tube target Cu, Co, other ??
>
> Cheers
> Ian Madsen
> 
> From: [EMAIL PROTECTED] [EMAIL PROTECTED]
> Sent: Tuesday, October 28, 2008 2:48 AM
> To: Rietveld_l@ill.fr
> Subject: Quantitative analysis
>
> Dear all,
>
> I have this question,
>
> I have been refined one mixture (of well-know percentage composition) of
> CaCO3, CaF2, SiO2 and Al2O3, with preferential orientation in CaCO3 (104)
> and CaF2 (111) with good results. When I add to the mixture FeCO3 and I
> refine with preferential orientation (104), it happens that when I don´t
> apply the preferential orientation in all this phases, I have correct
> values of percentage composition, but when I apply the preferential
> orientation the refinement is good but with incorrect values of percentage
> composition. This experiment has been taken in Bragg Brentano geometry.
> How I should refine this mixture?
>
> Thanks a lot by your help.
>
> Mario Macías
> Universidad Industrial de Santander
> Colombia
>
>

RE: Quantitative analysis

[Omotoso, Oladipo]

Mario,

You may want to check for the presence of solid solution in your siderite 
(especially Ca and Mg).  In my experience refining the PO in siderite with 
measurable amounts of Ca or Mg correlates significantly with the occupancy if 
the Fe/(Ca or Mg) ratio is not constrained to the true chemistry. The chemistry 
may be estimated by the d104 shift.

Dipo Omotoso
Natural Resources Canada
CETC-Devon
#1 Oil Patch drive, Devon AB. T9G 1A8.



-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Mon 10/27/2008 7:10 PM
To: [EMAIL PROTECTED]; Rietveld_l@ill.fr
Subject: RE: Quantitative analysis
 
Dear Mario,

Please tell me a little about the data collection conditions you used for this 
work:-

How was the sample prepared (hand ground, micronised in McCrone mill )
What was the tube target Cu, Co, other ??

Cheers
Ian Madsen

From: [EMAIL PROTECTED] [EMAIL PROTECTED]
Sent: Tuesday, October 28, 2008 2:48 AM
To: Rietveld_l@ill.fr
Subject: Quantitative analysis

Dear all,

I have this question,

I have been refined one mixture (of well-know percentage composition) of
CaCO3, CaF2, SiO2 and Al2O3, with preferential orientation in CaCO3 (104)
and CaF2 (111) with good results. When I add to the mixture FeCO3 and I
refine with preferential orientation (104), it happens that when I don´t
apply the preferential orientation in all this phases, I have correct
values of percentage composition, but when I apply the preferential
orientation the refinement is good but with incorrect values of percentage
composition. This experiment has been taken in Bragg Brentano geometry.
How I should refine this mixture?

Thanks a lot by your help.

Mario Macías
Universidad Industrial de Santander
Colombia

Re: Quantitative analysis

[Radovan Cerny]

Martin,

The reason of your bad experience with March-Dollase can be different, 
however, Leonid was right. The March-Dollase is normalized, the 
Rietveld-Toraya not. It can be easily normalized (see for example J. 
Appl. Cryst. 28(1995)247-253) but in all Rietveld codes I know it is not.


Best

radovan




Martin a écrit :
Sorry to disagree. Experience tells me otherwise - the March-Dollase 
correction has nearly always led to poor quant results for me. It most 
certainly cannot be applied safely.
 
Martin
 
--
 
M Vickers

Dept of Chemistry
UCL




 > Subject: Re: Quantitative analysis
 > Date: Tue, 28 Oct 2008 02:53:20 -0700
 > From: [EMAIL PROTECTED]
 > To: Rietveld_l@ill.fr
 >
 > Dear Mario,
 >
 > One more possible problem of applying preferred orientation 
corrections in QPA is that not all of them are normalized. For example, 
the March-Dollase correction is normalized and can be applied safely, 
but the Rietveld-Toraya correction is inapplicable to QPA as it does not 
preserve the scale normalization.

 >
 > Best regards,
 > Leonid
 >
 > ***
 > Leonid A. Solovyov
 > Institute of Chemistry and Chemical Technology
 > K. Marx av., 42
 > 660049, Krasnoyarsk Russia
 > Phone: +7 3912 495663
 > Fax: +7 3912 238658
 > www.icct.ru/eng/content/persons/Sol_LA
 >


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RE: Quantitative analysis

[Martin]

Sorry to disagree. Experience tells me otherwise - the March-Dollase correction 
has nearly always led to poor quant results for me. It most certainly cannot be 
applied safely.
 
Martin
 
--
 
M Vickers
Dept of Chemistry
UCL



> Subject: Re: Quantitative analysis> Date: Tue, 28 Oct 2008 02:53:20 -0700> 
> From: [EMAIL PROTECTED]> To: Rietveld_l@ill.fr> > Dear Mario,> > One more 
> possible problem of applying preferred orientation corrections in QPA is that 
> not all of them are normalized. For example, the March-Dollase correction is 
> normalized and can be applied safely, but the Rietveld-Toraya correction is 
> inapplicable to QPA as it does not preserve the scale normalization. > > Best 
> regards,> Leonid> > ***> 
> Leonid A. Solovyov> Institute of Chemistry and Chemical Technology> K. Marx 
> av., 42> 660049, Krasnoyarsk Russia> Phone: +7 3912 495663> Fax: +7 3912 
> 238658> www.icct.ru/eng/content/persons/Sol_LA> 
_
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Re: Quantitative analysis

[Leonid Solovyov]

Dear Mario,

One more possible problem of applying preferred orientation corrections in QPA 
is that not all of them are normalized. For example, the March-Dollase 
correction is normalized and can be applied safely, but the Rietveld-Toraya 
correction is inapplicable to QPA as it does not preserve the scale 
normalization. 

Best regards,
Leonid

***
Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
K. Marx av., 42
660049, Krasnoyarsk  Russia
Phone: +7 3912 495663
Fax:   +7 3912 238658
www.icct.ru/eng/content/persons/Sol_LA
***

--- On Mon, 10/27/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:

> From: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
> Subject: Quantitative analysis
> To: Rietveld_l@ill.fr
> Date: Monday, October 27, 2008, 3:48 PM
> Dear all,
> 
> I have this question,
> 
> I have been refined one mixture (of well-know percentage
> composition) of
> CaCO3, CaF2, SiO2 and Al2O3, with preferential orientation
> in CaCO3 (104)
> and CaF2 (111) with good results. When I add to the mixture
> FeCO3 and I
> refine with preferential orientation (104), it happens that
> when I don´t
> apply the preferential orientation in all this phases, I
> have correct
> values of percentage composition, but when I apply the
> preferential
> orientation the refinement is good but with incorrect
> values of percentage
> composition. This experiment has been taken in Bragg
> Brentano geometry.
> How I should refine this mixture?
> 
> Thanks a lot by your help.
> 
> Mario Macías
> Universidad Industrial de Santander
> Colombia