Dear Dr. Bianchini,
in such structures you have typically also stacking faulting (very
frequently h+k equal 3n yields narrow reflections, of a hexagonal
setting is adopted but it depends on the actual structure). That
broadening cannot be simply described as anisotropic size or micostrain
(although sometimes you can describe the most severe misfits with such
models). Perhaps to some extend it can be regarded as hkl-specific
anisotropic size.
In fact, antiphase boundaries is stacking faults, if you simply consider
the relation between fault plane and translation lattice.
To find recent examples also beyond the old works on metals, you might
check for works which have been performed using the software Diffax or
Faults.
Best regards
Andreas Leineweber
Am 12.08.2019 um 18:11 schrieb Bianchini, Matteo (INT):
Dear Rietveld people,
I am hoping to find some advice on microstructural effects.
I have a sample, a layered oxide (R-3m, with fcc oxygen packing) that
exhibits peculiar broadening of Bragg peaks in synchrotron XRD powder
data.
I tried using various strain and size formulations implemented in
Fullprof (Stephens for strain, spherical harmonics for size) but none
of them gives good results.
So I think the broadening is related to a very specific kind of
defect. Also, it is very clearly lorentzian.
Finally I found a pretty good fit using a specific rule for hkl, i.e.
l = 2n+1. I am not sure if this is the best possible rule, but it
works quite well.
I am trying to figure out what kind of defect specifically this might
relate to. I think it might be antiphase boundaries, but am not sure.
Most of the literature I could find on the subject relates to binary
alloys, not oxides.
If anyone has advice on how to physically interpret specific
broadening rules such as the one I found, or can point me to the
relevant literature, I would be very grateful.
Best regards
--------------------------------------------------------------------------------------------------
Dr. Matteo Bianchini
Postdoctoral researcher
Battery and Electrochemistry Lab - Karlsruhe Institute of Technology
Email: matteo.bianch...@kit.edu
Phone Office: +4972160826415
Personal: +4917674710480
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Prof. Dr. rer. nat. habil. Andreas Leineweber
Institute of Materials Science
TU Bergakademie Freiberg
Gustav-Zeuner-Str. 5
D-09599 Freiberg
Germany
Phone: +49-3731-39-2622
Fax: +49-3731-39-2604
http://tu-freiberg.de/fakult5/iww/
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