Dear colleagues, I would like first to thank everybody who responded to my question on Gaussian size broadening.
And now would like to ask another closely related (but "more practical") question: I think the easiest way to do particle size estimate in case when one has mixed alpha1/alpha2 (and/or a series of similar samples) is to do Rietveld or Le Bail fit and estimate particle size from the refined profile parameters (e.g. P and X in TCH PV). But once you have refined values for both P and X, you easily calculate "Lorentzian size" and "Gaussian size" - but (citing Woodward's lecture on size-strain analysis), "it is not immediately clear to me how to combine these results and get an accurate estimate of the crystallite size (though perhaps there may be a good way to do this)" Can anybody suggest such "good way"? This must be something really simple... Sincerely, Maxim. -----Original Message----- From: Nicolae Popa [mailto:[EMAIL PROTECTED] Sent: Tuesday, October 21, 2008 3:48 PM To: Maxim V. Lobanov; rietveld_l@ill.fr Subject: Re: question on size-strain analysis Hi, Besides strain and instrument also size broadening can be close to a Gaussian if the crystallite size distribution is very narrow. For zero dispersion of size distribution the size peak profile is about 75% Gaussian and 25% Lorentzian (on tails). For details see JAC (2002) 35, 338-346 (self citation) and other ref. cited there (Langford, Louer, Scardi (2000)) Best, Nicolae Popa ----- Original Message ----- From: "Maxim V. Lobanov" <[EMAIL PROTECTED]> To: <rietveld_l@ill.fr> Cc: "Дмитрий А. Павлов" <[EMAIL PROTECTED]> Sent: Tuesday, October 21, 2008 9:20 AM Subject: question on size-strain analysis > 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 > > > > > __________ NOD32 3541 (20081021) Information __________ > > This message was checked by NOD32 antivirus system. > http://www.eset.com > >
