X-Ray absorption and X-ray diffraction studies on molybdenum doped vanadium pentoxide

Abstract

Molybdenum doped vanadium pentoxide, (V_1 − xMo_x)₂O₅, is considered to be a suitable model substance for the investigation of oxidation catalysts based on vanadium molydenum mixed oxides. Series of the doped oxide with 0 ≤ x ≤ 0.20 have been investigated by X-ray absorption spectroscopy and diffraction. The mean vanadium valence as a function of the molybdenum content was determined, and a simple defect model was applied. The structure can be described as a distorted vanadium pentoxide structure for low dopand fractions up to x < 0.08 (single phase region). Further details of the local structure could be elaborated by EXAFS analysis. Lattice constants showing a dependence on x resulted from a structure refinement based on the Rietveld method. With increasing molybdenum content, the presence of a two phase region has been confirmed for x > 0.08.