[GSAS-II] GSAS-II Digest, Vol 267, Issue 1

[Victor Zenou]

Hi
About my question, after getting Bob's remark to avoid singular matrix, I
used a constraint on the sum of s.o.f parameter for  Ti and Sc (say 0.9),
and refined s.o.f of each, later repeating that up to 1.0.
Then I took the best fit to be the proper answer.

VIC


‫בתאריך יום ב׳, 8 ביוני 2020 ב-20:00 מאת <‪gsas-ii-request at aps.anl.gov‬‏>:‬

> Send GSAS-II mailing list submissions to
>         gsas-ii at aps.anl.gov
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         https://mailman.aps.anl.gov/mailman/listinfo/gsas-ii
> or, via email, send a message with subject or body 'help' to
>         gsas-ii-request at aps.anl.gov
>
> You can reach the person managing the list at
>         gsas-ii-owner at aps.anl.gov
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of GSAS-II digest..."
>
>
> Today's Topics:
>
>    1. Parameters that won't refined (Victor Zenou)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 8 Jun 2020 09:29:32 +0300
> From: Victor Zenou <zanov at post.bgu.ac.il>
> To: gsas-ii at aps.anl.gov
> Subject: [GSAS-II] Parameters that won't refined
> Message-ID:
>         <CAOFFwJ43WRN=F4_psG6_JpPE=Y7znJDz5mPfD0=
> tjxx4+ODcKw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi
>
> I'm working on Sc-doped TiO2 nano-crystallites. As Sc and Ti have close
> atomic number, and therefore atomic scattering factor, XRD cannot be used
> to differentiate between Sc and Ti, sitting on the same Wyckoff atomic
> position. On the other hand, the neutron scattering length of Sc is
> different from Ti.
>
> Therefore, I'm using neutron diffraction (ND) data and X-ray diffraction
> (XRD) data of a few Sc-doped TiO2 samples in a joint refinement using
> GSAS-II. Among the usual lattice parameters and sample displacement (bragg
> brentano geometry; XRD) or zero shift (*Debye**-*Scherrer ; ND) the
> refinement includes Ti and Sc site occupancy parameters (s.o.f) in addition
> to the crystallite size. These site occupancy parameters are refined at the
> end, however they won't  be "refined" (refinement ends without changing the
> s.o.f. parameters).
>
> Changing these  Ti/ Sc s.o.f manually  can give better results. It is more
> complicated as there are some vacancies at the same position.
>
> Does anybody have an idea how to refine these s.o.f of Ti and Sc?
>
> Best regards,
>
> Victor Zenou
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://mailman.aps.anl.gov/pipermail/gsas-ii/attachments/20200608/e11ab9f4/attachment-0001.html
> >
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> GSAS-II mailing list
> GSAS-II at aps.anl.gov
> https://mailman.aps.anl.gov/mailman/listinfo/gsas-ii
>
> ------------------------------
>
> End of GSAS-II Digest, Vol 267, Issue 1
> ***************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.aps.anl.gov/pipermail/gsas-ii/attachments/20200608/c80b434c/attachment.html>