Dear Lubomir Smrock,
linear pattern analysis is _not_ Rietveld, this was a common QPA
method prior to Rietveld QPA. In a Rietvel QPA, one must refine
the lattice parameter at least. And that makes it nonlinear.
Depending on the sample, one may decide to add more nonlinear
details to the
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
PROTECTED]
Sent: Wednesday, 21 March 2007 7:48 PM
To: rietveld_l@ill.fr
Subject: Re: Problems using TOPAS R (Rietveld refinement)
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
for wollastonite though!
I will shut up at this point as I trying to avoid doing clay analysis!
Pam
-Original Message-
From: David L. Bish [mailto:[EMAIL PROTECTED]
Sent: March 21, 2007 9:11 AM
To: rietveld_l@ill.fr
Subject: Re: Problems using TOPAS R (Rietveld
to investigate it.
Cheers
Alan
-Original Message-
From: Lubomir Smrcok [mailto:[EMAIL PROTECTED]
Sent: Wednesday, 21 March 2007 5:50 PM
To: rietveld_l@ill.fr
Subject: Re: Problems using TOPAS R (Rietveld refinement)
Gentlemen,
I've been listening for a week or so and I am really wondering
From: Whitfield, Pamela [mailto:[EMAIL PROTECTED]
Sent: Wednesday, March 21, 2007 7:51 AM
To: rietveld_l@ill.fr
Subject: RE: Re: Problems using TOPAS R (Rietveld refinement)
I have to disagree with that; at least on a practical front with lab XRD. I
have done measurements myself with samples
: Re: Problems using TOPAS R (Rietveld refinement)
My limited experience with X-ray capillary measurements of ultra fine clay
minerals suggests that you could have significant preferred orientation along
the b* axis. It is actually a good way of determining aspect ratios in
phyllosilicates
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
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,
Mr. Kleeberg,
Read the paper that you send to me, ´´RIETVELD ANALYSIS OF DISORDERED LAYER
SILICATES``, and I have some questions about it.
In the refinement of chlorite minerals with well defined disordering (layers
shifting by exactly b/3 along the three pseudohexagonal Y axis), you
,
Leandro
From: AlanCoelho
[EMAIL PROTECTED]
Reply-To: rietveld_l@ill.fr
To: rietveld_l@ill.fr
Subject: RE: Problems using TOPAS R (Rietveld refinement)
Date: Fri, 16 Mar 2007 09:56:33 +1100
Leandro
Not sure what the purpose of your refinement is but if it's
quantification
then your results would
= Exp(-b /D_spacing^2)
Does it give reasonable values!?
Regards,
Leandro
From: AlanCoelho [EMAIL PROTECTED]
Reply-To: rietveld_l@ill.fr
To: rietveld_l@ill.fr
Subject: RE: Problems using TOPAS R (Rietveld refinement)
Date: Fri, 16 Mar 2007 09:56:33 +1100
Leandro
Not sure what the purpose of your
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
Subject: Re: Problems using TOPAS R (Rietveld refinement)
Ok, I´m starting to have sucess in the kaolinite refinement, the
quantification is giving me reasonable values. I´m refining the thermal
factors, all the atoms positions in the kaolinite, the lattice parameters
and the cystallite size
To: rietveld_l@ill.fr
Subject: Re: Problems using TOPAS R (Rietveld refinement)
Ok, I´m starting to have sucess in the kaolinite refinement, the
quantification is giving me reasonable values. I´m refining the thermal
factors, all the atoms positions in the kaolinite, the lattice parameters
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
Reinhard Kleeberg said:
There are not so much trials published to find a
working solution for practical Rietveld quantification of clays. One
would be a self-citation of a paper, so I can't do this here in the list.
A good one is :-)
Pitfalls in Rietveld Phase Quantification of Complex
Or, to see how bad the results from Rietveld refinements of kaolintes are
try review
paper in
Zeitschrift fuer Kristallographie 210(3) 177-183, 1997
lubo smrcok
On Wed, 14 Mar 2007, Alan Hewat wrote:
Reinhard Kleeberg said:
There are not so much trials published to find a
working solution
: Re: Problems using TOPAS R (Rietveld refinement)
Date: Mon, 12 Mar 2007 13:35:54 -0300
I think that I just did a good job in my quantification: 50,2% calcite and
49,8% dolomite. Now I´m moving foward to a sinthetic mixture of calcite,
dolomite and kaolinite.
I have other questin, how can I
Leandro Bravo said:
I don´t think that the kaolinite CIF that I´m using is working well, I´m
refining the temperature factors and it´s giving me non realistic numbers.
Can somebody send me a trustable kaolinite CIF, with good temperature
factors?!
You will find a dozen papers on the structure
Subject: Re: Problems using TOPAS R (Rietveld refinement)
Date: Mon, 12 Mar 2007 10:39:41 -0600
Leandro :
here is an example of calcite I used. You can use min and max to confine
the parameters.
One way to know whether it is right is to mix a known fraction of a
compound, e.g. ZnO with a ratio
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