Investigation of the local structure and the effects of the orbit reduction factor on the EPR g-factors for octahedral (CrO6)9− cluster in TiO2:Cr3+ and MgO:Cr3+ systems

Abstract

A theoretical method for studying the inter-relation between electronic and molecular structure has been proposed based on the complete energy matrices for a d(3) configuration ion in a tetragonal ligand-field. By means of this method, the local structure for Cr(3+) ion doped in oxides TiO(2) (anatase) and MgO has been determined. The calculated results indicate that the local structure of the (CrO(6))(9-) cluster in TiO(2):Cr(3+) and MgO:Cr(3+) systems exists as a compressed distortion relative to the regular octahedron. Meanwhile, the dependence of the EPR zero-field splitting parameter D on the local structure parameter Delta R (Delta R = R(1)-R(2)) has been revealed. In addition, the relation between the EPR g-factors (g(II),g(perpendicular to),Delta g) and the orbit reduction factor k has been discussed for the two systems, suggesting that the orbit reduction factor k is very important to understand the EPR g-factors. (C) 2009 Elsevier B.V. All rights reserved.