Dear Ahmed,
two different things should be distinguished:
- the physical possibility do the refinement
- the mathematical way do implement the constraints in eg Fullprof
Concerning the first point, as it has already been pointed out, it is
not possible to refine site occupancies of two atoms sha
Our chemical engineers like to make perovskites with about 6 elements in
two sites for their solid state fuel cells...
On Mon, 2 Sep. 2019, 16:15 Le Bail Armel, wrote:
> If more than 2 atoms sharing the same site, then fire the chemist...
>
> Armel
> +
If more than 2 atoms sharing the same site, then fire the chemist...
Armel
++
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Adding a little bit to the previous answers,
aside from using neutron diffraction, on can also use anomalous
diffraction close to the absorption edge of the respective chemical
elements. This requires a synchrotron source in most cases (unless one
happens to have just the right exotic X-ray tu
Dear all,
Thank you very much for your prompt and kind suggestions.
Best regards,
Ahmed Subrati
From: Luca Lutterotti
Sent: Monday, September 2, 2019 7:22 AM
To: Ahmed Subrati ; rietveld_l@ill.fr
Subject: Re: Simultaneous refinement of multiple atoms sharing
With 3 atoms, as Larry and Alan explain it cannot be done unless you have
additional info (e.g. chemical info). In our lab, if the three atoms or at
least 2 are in the range for XRF, we do a combined XRD+XRF refinement.
Luca
---Luca
Lutterotti---
>how three atoms, sharing the same xyz position, could be refined in terms of
>their occupancies via FullProf
One of many possible options is to set 11.0 for one atom and -10.5 for the two
others.
***
Leonid A. Solovyov
Institute of Chemistry
Even with neutron diffraction :-) you can only refine the scattering power
(length) of each site. When you refine the occupancy of two atoms on a
single site you are adding additional "information" by assuming that the
site is fully occupied by one or the other. That may be true, or not. If
the sca
On 8/31/19 9:44 AM, Ahmed Subrati wrote:
Dear all,
I wanted to ask how three atoms, sharing the same xyz position, could be refined
in terms of their occupancies /via /FullProf. We know that for the case of two
atoms, the first atom is set as 11.0 and the second one as -11.0 so that their
sum