Solid state solubility between SnO2 and (FeSb)O-4 at high temperature

The solubility in the solid state was investigated for the pseudo-binary system SnO2-(FeSb)O-4 at high temperature. Stoichiometric amounts of pure SnO2 and (FeSb)O-4 powders were mixed and reacted in air at 1373 K. Solid state solubility was ascertained in the whole compositional range at high temperature, whereas at low temperature a miscibility gap occurs. The structural refinement performed according to the Rietveld method reveals that the (Sn2xFe1-xSb1-x)O-4 solid solution (0 <= x <= 1) crystallizes in the tetragonal system with a rutile-type structure. Negative deviations from Vegard's law were observed. An anisotropic broadening of the X-ray reflections was observed and analysed by means of Williamson-Hall plots.