>We are working on graphite intercalates with adsorbed gases. The XRD
>shows nicely indexable peaks with Warren-like lineshapes. Does anybody
>know how to model these profiles in a standard package. We have
>been using GSAS.
Alan Hewat (hewat@ill.fr) replied:
>Philip, have a look at an article by Traecy, Newsam and Diam in Proc.Roy.Soc.
>A433 p 499. The program for faulted 2D structures can be obtained from the
>authors, and is also part of BioSym software (ask John Newsam). Jean Pannetier
>here has adapted it to run on a Mac. (and hopefully a Silicon Graphics Indy ;-)
As P. Reynolds mentions GSAS, one may suppose than he expects to model
its profiles together with structure refinement in a Rietveld-type
process. To my knowledge this is possible by an empirical approach
in a lot of Rietveld packages at one condition : intrinsec peak
broadening should corresponds to symmetrical profiles...
This may not be the case of graphite intercalates due to faulted 2D
structures for which a Rietveld-type refinement would require a simple
general relation between faults and line-profile of any reflection :
a challenge.
Now, simulated patterns may be realized that could help in the data
interpretation. Other softwares than DIFFaX (Treacy, Newsam and Deem
in Proc. Roy. Soc. Lond. A433, 499-520, 1991) exist. See for instance
PRECRAY, SIMVAX and SIMVAX1 (Espinat, Thevenot, Grimoud and El Malki,
J. Appl. Cryst. 26, 368-383, 1993). Have also a look on fits of glassy
carbon powder diagrams in J. Appl. Cryst. 18, 320-325 (1985) by H.
Boysen.
___________________________________________________________________
Armel LE BAIL armel@ONE.univ-lemans.fr
Laboratoire des Fluorures
Universite du Maine
72017 Le Mans Cedex
FRANCE
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