[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[sdpd] Indexing problem
Dear all,
I encounter a (serious) problem when trying to index an X-ray powder
pattern. The data was measured on a good diffractometer (Philips
X-celerator, Cu Kalpha1;-Brag-Brentano geometry) (lowest FWHM~0.06 °) with
a step of 0.016° and a lot of counting time.
The sample has a perovskite like structure and undergoes a number of
structural transitions when heating. Triclinic at room temperature (I have
refined this one), unknown intermediary temperature phase, and a
tetragonal high temperature phase (I have refined this one too).
When indexing with the majority of the available software (Dicvol, Treor,
Ito?) alone or in the Crysfire suite, in the front of the list I get a
monoclinic cell a=7.86 b=7.68 c= 7.72 A and Beta~90.3° with rather good
agreement factors (M20 about 180). Refining the cell in FullProf, gives a
perfect fit for the low 2Theta pattern (2Theta<80°), but at high 2Theta
values there are some shifts in the positions or the reflections.
I have thought that this could came from some instrumental error, but the
tetragonal high temperature phase give a perfect fit even in this are, so
I have excluded this possibility.
Is someone has any idea or maybe has encountered the same kind of problem,
please help me.
Thank you in advance
=====
Cristian PERCA
Laboratoire de Physico-Chimie de l'Etat Solide
Bât. 414 - Université Paris XI
91405 ORSAY Cedex - France
http://www.u-psud.fr/chimsol
Tél : 01 69 15 48 04
cristian.perca...@lpces.u-psud.fr
cristianperca...@yahoo.com
__________________________________
Do you Yahoo!?
Meet the all-new My Yahoo! - Try it today!
http://my.yahoo.com
------------------------ Yahoo! Groups Sponsor --------------------~-->
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!
http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/UIYolB/TM
--------------------------------------------------------------------~->
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/sdpd/
<*> To unsubscribe from this group, send an email to:
sdpd-unsubscribe...@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/