Electron paramagnetic resonance investigation of the paramagnetic centres in polycrystalline MoO3
Abstract
The defect MoO3 was obtained by thermal decomposition of hexakisammonium heptamolybdate in vacuo at 630 K. Different signals present in the EPR spectrum of reduced MoO3 and those appearing in the course of oxidation, were attributed to Mo5+ ions in various symmetry, situated in different sites of the MoO3 lattice. The signal of Mo3+ ions with effective spin S= 1/2 was observed in the EPR spectrum of both reduced and reoxidized MoO3. A hole centre (Mo—O)5+ was found in reoxidized MoO3. Various methods of stabilization of reduced molybdenum in the MoO3 lattice were postulated.