LAUSR

Abstract A novel mixed valence tellurium oxide, TiGa 0.67 Te 2.33 O 8 , was synthesized and its crystal structure determined using the X-ray powder diffraction technique. The obtained oxide was found to crystallize in a cubic unit-cell, Ia 3 ¯ space group, with the lattice parameter a  = 10.9557(1) A. Rietveld refinement of the structure led to ultimate confidence factors R p  = 7.63 and R wp  = 6.71. This structure was based on slabs containing groups of (Te/Ga)O 4 joined by the metal cations Ti 4+ . The structure analysis showed a cation ordering of Te 4+ and Te 6+ yielding a TiGa 2/3 Te 7/3 O 8 formula. The IR and RAMAN spectra confirmed the presence of the TiO 6 and (Te/Ga)O 4 groups. The dielectric anomalies observed at 500 K were attributed to the mixed valence structure, arising from the mixed-valence Te 6+ /Te 4+ . We detected only one peak in thermal behavior by the DTA/TG analysis; which implied a melting reaction.