MIXED-VALENCE EFFECTS IN TELLURIUM-MOLYBDENUM OXIDES

Powdered samples of α-Te2MoO7, TeMo5O16, α-TeO2 and MoO3 were studied by various spectroscopic techniques (XPS, IR, Raman, diffuse reflectance). Observed Mo(3d 1 2-3d 5 2 and Te(3d 3 2-3d 5 2 binding energies, combined with bond-strength bond-length calculations, indicate the presence of Te(IV) in both α-Te2MoO7 and TeMo5O16. In the latter compound some Mo(VI) valencies are trapped in specific cation sites whereas at other sites considerable Mo(V)-Mo(VI) mixing occurs; Mo(IV) contributions are ruled out. The class II mixed valence system TeMO5O16 is formally best described as TeO2·3MoO3·Mo2O5. Assignments of skeletal modes are suggested for MoO3, α-MoO3·H2O, α-Te2MoO7 and TeMo5O16. © 1979.