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: "Leonid Solovyov" <[EMAIL PROTECTED]>
To: <rietveld_l@ill.fr>
Sent: Tuesday, October 21, 2008 10:04 AM
Subject: Re: question on size-strain analysis
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
__________ NOD32 3541 (20081021) Information __________
This message was checked by NOD32 antivirus system.
http://www.eset.com
