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
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