Dear Maxim, Gaussian peak shape is, normally, related to the instrumental, strain and/or lattice distribution broadening. The Williamson-Hall plot shows the dependency of broadening on the diffraction angle and if this dependency can not be explained by strain then it is most probably instrumental. If you use the Bragg-Brentano geometry a possible reason might be a loose powder, sample misalignment or surface roughness.
Regards, Leonid ******************************************************* Leonid A. Solovyov Institute of Chemistry and Chemical Technology K. Marx av., 42 660049, Krasnoyarsk Russia Phone: +7 3912 495663 Fax: +7 3912 238658 www.icct.ru/eng/content/persons/Sol_LA ******************************************************* --- On Tue, 10/21/08, Maxim V. Lobanov <[EMAIL PROTECTED]> wrote: > From: Maxim V. Lobanov <[EMAIL PROTECTED]> > Subject: question on size-strain analysis > To: rietveld_l@ill.fr > Cc: "Дмитрий А. Павлов" <[EMAIL PROTECTED]> > Date: Tuesday, October 21, 2008, 7:20 AM > Dear colleagues, > > I have a probably very basic question related to > size-strain analysis: > > we have a pattern of a nanocrystalline oxide, which shows > (from > Williamson-Hall plot) almost purely size broadening, and > shape of > reflections is to good accuracy Gaussian. > I am curious what type of microstructure this Gaussian > behavior can reflect. > Maybe it is just something usual, but so far I had only > observed > predominantly Lorentzian broadening in similar materials... > > Sincerely, > Maxim. > > > ------------------------------------------- > Dr. Maxim Lobanov > R&D Director > Huntsman-NMG > mailto: [EMAIL PROTECTED] > > ********************************* > If you encounter any difficulties > sending e-mails to the addresses in huntsman-nmg.com > domain, > this could be due to the our spam filter malfunction. > In case of such an event please send a message to > [EMAIL PROTECTED] > > Please note that the old domain nmg.com.ru does not exist > anymore - > please update your address book accordingly