Hi Matthew,
About the form factors : there is an active community doing "Quantum
Crystallography" or charge density analysis with the IUCr. Some of them have
been running a nice series of online lectures recently:
https://qcrwebinar.chem.uw.edu.pl/
You can find many experts there, and there are also recordings on youtube. For
Al2O3 there should be several charge density studies in the literature.
Extinction is usually discussed, as well as f' and f" values. More accurate data
is a continuing need for that kind of work, so perhaps a combined refinement of
powder and single crystal data can be interesting.
For Al2O3: this paper (https://doi.org/10.1107/S0567739482001478) gives Al:1.32+
and O:0.88-. You can probably find other numbers in the literature.
Best,
Jon
On 22/02/2023 04:14, Matthew Rowles wrote:
Warning, anecdote ahead! (and this wasn't the point of my original post...)
I get better (flatter difference plot) fits with SRM676A using charged atoms
(Al+3, O-2) than I do with neutral. (Co Ka, lab BB diffractometer)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Please do NOT attach files to the whole list <alan.he...@neutronoptics.com>
Send commands to <lists...@ill.fr> eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
