Re: Size Strain In GSAS

[Luca Lutterotti]

Dear Apu,
difficult to say without seeing the pattern with your actual fitting. 
Broadening with small domain size is normally more easy to fit. It 
could be you didn't use the proper function or refines all necessary 
parameters, or there is an anisotropic broadening or faulting.
Every sample/analysis has his own story.
Try to put a picture of the fitting somewhere on the web and post here 
a link to the picture as attachments are not permitted in the list. 
This would be better as everyone can see it and give you some 
suggestions.

        Luca
On Mar 25, 2005, at 12:00, [EMAIL PROTECTED] wrote:
Dear Prof. Lutterotti,
 I was also aware of the fact that GSAS is not made for Size Strain 
analysis. I got interested to use the Size strain refinement feature 
of GSAS only after going through the article :
"Size-strain line broadening analysis of the ceria round-robin sample" 
by Prof. D. Balzar et. al. Journal of Applied Crys. 37(2004)911-924.

In that round robin results they have reported the size strain 
obtained from GSAS.

I my case also when I am trying with GSAS, the diffraction pattern is 
fitting well except the peak braodening. I think this brodening is due 
to small domain size effect. I that case how will I obatin a good fit 
with GSAS.

Thanking you.
Best Regards,
Apu



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Apu Sarkar
Research Fellow
Variable Energy Cyclotron Centre
Kolkata 700 064
phone: 91-33-2337-1230 (extn. 3190)
Fax:   91-33-2334-6871
INDIA
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----- Original Message -----
From: Luca Lutterotti <[EMAIL PROTECTED]>
Date: Friday, March 25, 2005 3:31 pm
Dear Apu,
I know I will start up a "good" debate here, but size-strain
analysis
with GSAS is a non-sense. The program was not written with that
purpose
in mind and in fact it does not contains the instrumental
aberration
part of the broadening that is necessary for such computation.
Indeed it is possible to get at end some size-strain data, but
quite
hard as you have to do all correction later and out of the
program. So
it is like using GSAS for peak fitting, so better to use a peak
fitting
dedicated program.
        Best wishes,
                Luca Lutterotti
On Mar 25, 2005, at 7:15, [EMAIL PROTECTED] wrote:
Dear All,
I am trying to perform Rietveld refinement on a very simple
system
using GSAS. I have obtained a reasonable fit except the peak widths.
 I want to use the size and strain refinement option in GSAS to
make
the fit well.
Please tell me how to use the SIZE STRAIN refinement option in GSAS.
P.S. I am using the EXPGUI.
Thanks in advace.
Regards,
Apu
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 Apu Sarkar
Research Fellow
Variable Energy Cyclotron Centre
Kolkata 700 064
phone: 91-33-2337-1230 (extn. 3190)
Fax: 91-33-2334-6871
INDIA
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