Investigations of the defect structures and the EPR parameters for the substitutional Mo5+ centers in rutile type crystals

Abstract

The defect structures and the electron paramagnetic resonance parameters for the substitutional Mo5+ centers in rutile type SnO2, TiO2 and GeO2 crystals are theoretically investigated from the perturbation formulas of these parameters for a 4d1 ion in rhombically compressed octahedra. The [MoO6]7− clusters suffer the Jahn–Teller effect and transform the ligand octahedra from original elongation on host tetravalent sites to compression in the impurity centers, with additional smaller rhombic (perpendicular) distortions when compared with those in the hosts. The defect structures and the importance of the ligand contributions are discussed.