Dear all,
I think Jon is right. In the case of Cu this is the position of a (100)
reflection of a hcp polytype. I have seen this feature in a couple of
cases, and presence of this feature is sometimes taken as a sign for a
two-phase character of the specimen, which need not be the case (other
reflections from the hcp-like polytype generally are then lacking). In
the case of Copper or alpha-Cu alloys a real two-phase character of the
material is very unlikely. Diffax and Diffax_plus are able to model this
feature.
The mentioned ice example is reported in some more depth in PNAS 109
(2012) 21259
Best regards
Andreas
On 07.04.2014 09:05, Jonathan WRIGHT wrote:
On 06/04/2014 08:06, Leonid Solovyov wrote:
The faulting model in DDM gives nearly perfect agreement with the
experiment:
http://sites.google.com/site/ddmsuite/home/Copper-DDM.png
It looks a little bit reminiscent of this pattern for ice:
http://www.science24.com/paper/15441
...but the little step at about 40.5 degrees doesn't seem to be in the
model? Isn't that coming from some sort of defects or diffuse
scattering? Not that I would attempt to model something like that, but
a 1D "rod" in 3D reciprocal space (coming from 2D defects) gives
step-like profiles in a 1D powder pattern. Although you generally only
know that if you've also got data from a single crystal :-)
Cheers,
Jon
--
Dr. Andreas Leineweber
Max-Planck-Institut fuer Intelligente Systeme
(ehemals Max-Planck-Institut fuer Metallforschung)
Heisenbergstrasse 3
70569 Stuttgart
Germany
Tel. +49 711 689 3365
Fax. +49 711 689 3312
e-mail: a.leinewe...@mf.mpg.de
home page of department: http://www.is.mpg.de/de/mittemeijer
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