<div dir="rtl"><div dir="ltr">Hi</div><div dir="ltr">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.</div><div dir="ltr">Then I took the best fit to be the proper answer.</div><div dir="ltr"><br></div><div dir="ltr">VIC</div><div dir="ltr"><br></div></div><br><div class="gmail_quote"><div dir="rtl" class="gmail_attr">בתאריך יום ב׳, 8 ביוני 2020 ב-20:00 מאת <<a href="mailto:gsas-ii-request@aps.anl.gov">gsas-ii-request@aps.anl.gov</a>>:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Send GSAS-II mailing list submissions to<br>
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Today's Topics:<br>
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1. Parameters that won't refined (Victor Zenou)<br>
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Message: 1<br>
Date: Mon, 8 Jun 2020 09:29:32 +0300<br>
From: Victor Zenou <<a href="mailto:zanov@post.bgu.ac.il" target="_blank">zanov@post.bgu.ac.il</a>><br>
To: <a href="mailto:gsas-ii@aps.anl.gov" target="_blank">gsas-ii@aps.anl.gov</a><br>
Subject: [GSAS-II] Parameters that won't refined<br>
Message-ID:<br>
<CAOFFwJ43WRN=F4_psG6_JpPE=Y7znJDz5mPfD0=<a href="mailto:tjxx4%2BODcKw@mail.gmail.com" target="_blank">tjxx4+ODcKw@mail.gmail.com</a>><br>
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<br>
Hi<br>
<br>
I'm working on Sc-doped TiO2 nano-crystallites. As Sc and Ti have close<br>
atomic number, and therefore atomic scattering factor, XRD cannot be used<br>
to differentiate between Sc and Ti, sitting on the same Wyckoff atomic<br>
position. On the other hand, the neutron scattering length of Sc is<br>
different from Ti.<br>
<br>
Therefore, I'm using neutron diffraction (ND) data and X-ray diffraction<br>
(XRD) data of a few Sc-doped TiO2 samples in a joint refinement using<br>
GSAS-II. Among the usual lattice parameters and sample displacement (bragg<br>
brentano geometry; XRD) or zero shift (*Debye**-*Scherrer ; ND) the<br>
refinement includes Ti and Sc site occupancy parameters (s.o.f) in addition<br>
to the crystallite size. These site occupancy parameters are refined at the<br>
end, however they won't be "refined" (refinement ends without changing the<br>
s.o.f. parameters).<br>
<br>
Changing these Ti/ Sc s.o.f manually can give better results. It is more<br>
complicated as there are some vacancies at the same position.<br>
<br>
Does anybody have an idea how to refine these s.o.f of Ti and Sc?<br>
<br>
Best regards,<br>
<br>
Victor Zenou<br>
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