BaTl0.5Te0.5O3: a simple cubic perovskite oxide with pentavalent tellurium

BaTl0.5Te0.5O3 has been synthesized for the first time with a perovskite-related structure. Synchrotron X-ray diffraction study shows that this compound has a primitive cubic unit cell with Tl and Te atoms disordered at the octahedral site of the perovskite structure. The compound shows high electrical conductivity, but with an activated process for conduction. The observed structural parameters and electrical behavior suggest that the valence picture in the title compound is BaTl0.5+3Te0.5+5O3. The estimated ionic radius for Te+5 in octahedral coordination is similar to 0.62 Angstrom, which is close to the value observed for Sb5+ as expected from their location in the periodic table. (C) 2000 Elsevier Science Ltd. All rights reserved.