Hi,
Self Citation: "NIST Standard Reference Materials for
Characterization of Instrument Performance" Industrial Applications
of X-ray Diffraction Ed by F. H. Chung & D. K. Smith, pp 903-917. A
pdf is available; email to request.
In this I outline how I use SRM 660 (it was 660 in 2000, then it was
660a until ~July '07, we are working on 660b) for qualifying and
characterizing instrument performance with both profile fitting and
the Rietveld method, via GSAS. I suggest obtaining a set of TCH
parameters with LaB6. The instrument specific ones thereafter
remained fixed while the other are used as a "floor" for refined
values. With this approach I was able to obtain stable and
meaningful results from laboratory equipment.
Regards,
Jim
At 08:25 PM 11/30/2008, you wrote:
To all:
What is the correct procedure for refining U,V,W? It is my
understanding that those parameters are a function of instrument
geometry. Does one use a standard material to determine U,V,W and
then fix their values for the instrument you're using?....or do the
values of U,V,W change depending on the sample being examined? If
so, why do the values change?
Thanks in advance.
Frank May
________________________________
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Sun 11/30/2008 1:32 PM
To: rietveld_l@ill.fr
Subject: Re: I am a newcome, how can I begin my rietveld refinement analysis
Hi, Li:
To me, the most wonderful tool to determine initial peakshape parameters is
CMPR.
CMPR is especially oriented to GSAS and gives you GU, GV, GW etc. And when
you use EXPGUI for GSAS, you can also try Graphs->widplt to see how FWHM
develops when parameters are tuned.
When you prefer Fullprof, you should take a factor to get U, V, W etc. i am
not sure about the facor exactly, maybe GX~100X(X=U, V, W), er..? Anyway,
just go ahead and make a try.
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/
James P. Cline
Ceramics Division
National Institute of Standards and Technology
100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ]
Gaithersburg, MD 20899-8523 USA
[EMAIL PROTECTED]
(301) 975 5793
FAX (301) 975 5334
