I am not an expert on strain analysis, but can offer a few comments. The first is that GSAS-II is way better for this than GSAS/EXPGUI for the simple reason that it decouples the instrumental broadening (which should be determined from a standard) from the sample-depended terms (size/microstrain) and offers a three-level approach to the model (isotropic/uniaxial/full-blown-Stephens-expansion) which is also nice. The values for these broadenings are expressed as a function of the peak widths (delta d/d or equivalently delta Q/Q, no units).
As to what one can do with a lab instrument: usually one wants to separate size broadening from strain broadening (unless the former can be ruled out); this requires data over a wide angular range. This depends on the scattering from the sample as well as the instrument. Likewise, it is very hard to discern small broadening values affecting peaks that are already broad from a low resolution instrument — so it depends on your project and is very hard to say much on a general basis. Brian On Dec 19, 2016, at 6:45 AM, Daxu Liu <[email protected]<mailto:[email protected]>> wrote: Hi, everyone, Someone can supply some information on analyzing strain using GSAS? Because one of the reviewers asked me to determine the stain of biogenic calcite, however I don't know how to analyze the refinement data to obtain the strain. I wonder whether the resolution of conventional Bragg-Brentano X-ray diffratometer is able to determine the strain. I know GSAS does describe the strain using some functions for conventional XRPD data. How to output the corresponding data to calculate the strain. Best regrads, Daxu ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <[email protected]<mailto:[email protected]>> Send commands to <[email protected]<mailto:[email protected]>> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/[email protected]/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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