Hello fellow researchers.
As I'm new to the list, first few words about me. I'm a PhD student in
the laboratory of Inorganic Chemistry at the University of Helsinki.
I've been responsible for our XRD equipment for a couple of years now
and as it seems that the subject of my dissertation will (after all)
be closely related to XRD, I've started to teach myself some Rietveld
refinement skills. I'm still not very experienced in this field and in
order to not invent the wheel again, I decided to join here and start
to bug you with my questions :-)
I haven't seen much thin film related discussion here, so I'm probably
going to start some, at least until MAUD forum reopens. This is
related to the following example:
http://www.helsinki.fi/~mwheikki/temp/MAUD_example.pdf From the widths
of the peaks alone I'd suspect that there has to be some anisotropy in
crystallite sizes, right? The uppermost image in the pdf depicts the
isotropic situation. The middle one is refined with Popa anisotropic
rules and the result is slighly better. However, the best fit is
achieved with some exponential harmonics describing slight fiber
texture.
The question is, is this a reasonable approach to fit thin films? I
mean, I could refine anything if I just add more and more variables,
but I'm hoping this to be physically valid approach. As opposed to
powders, thin films can grow in a more anisotropic manner, even
showing fiber textures. This was measured with 1° constant incident
angle, though, and I'm not sure how successfully I can use this kind
of texture to describe non-symmetric measurements.
Do you think I'm heading to right or wrong direction here? I'm glad if
someone has time to read this through.
Best regards and successfull start to your year,
Mikko
---
Mikko Heikkilä, M.Sc.
Laboratory of Inorganic Chemistry
Department of Chemistry
P.O.Box 55
FI-00014 University of Helsinki
phone: +358 9 191 50216
mobile: +358 440 572 372
email: mikko.j.heikk...@helsinki.fi
