Frank wrote,
>......
>Now the big question? What do I do with data with this good
>resolution? I know there are differences, but is there software to do
>something with it? For instance, I have a pattern with clearly
>resolved, indexed peaks from about 13-33 degrees 2-theta which have
>varying breadths. The variations of of the order of 0.04-0.10 degrees
>2-theta. Over the years I have looked at patterns from this material
>which appear to vary as a function of preparation (which causes
>differences in particle shape--by SEM). Any suggestions?
>
>I have tried Rietveld refinement on the pattern(s) (structure is known),
>but the program I'm using doesn't allow me to accommodate the different
>peak breadths. Any hope for Rietveld?
If the anisotropic broadening is due to crystallite and/or microstrain
and/or planar faulting there are Rietveld programs that allows anisotropic
broadening. The first work on that was again due to Armel Le Bail (anything
seem to go around him) (French congress, I didn't have the reference on my
desk now), but actually there are more options availables.
Maud is one of these Rietveld program (use the Popa model for anisotropic
broadening and also planar defect from Warren models). I should remark the
goodness of the Popa model (J. Appl. Cryst. (1998). 31, 176-180).
But probably you should got a reply also from Bergmann that bgmn will do
anything.
I think also GSAS should have something because I remember Von Dreele
presenting something on anysotropic broadening two years ago. May be others
program are availables too.
Best regards,
Luca Lutterotti
-----------------------Luca Lutterotti----------------------------
Dipartimento di Ingegneria dei Materiali, Universita' di Trento,
via Mesiano 77, 38050 Trento, Italy
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