A uniform research on the optical and EPR spectral data for the trigonal Cr3+ center in Cr3+-doped Ca3Ga2Ge3O12 garnet

Abstract

This article represents a uniform calculation for the optical and electron paramagnetic resonance (EPR) spectral data of the trigonal Cr3+ center in Cr3+-doped Ca3Ga2Ge3O12 (CGGG) garnet crystal by using the full diagonalization (of energy matrix) method. The method is built on the two-spin-orbit-parameter model where the contributions due to both the spin-orbit parameter of central dn ion in the traditional crystal-field theory and that of ligand ion via covalence effect are comprised. The calculated results indicate that the observed ten optical and EPR data (seven optical bands and three EPR parameters g//, g⊥, D) can be rationally interpreted by this method with only four adjustable parameters. The crystal field parameters applied in the calculation are evaluated by the superposition model, which leads the defect structure of Cr3+ center in CGGG: Cr3+ crystal to be determined. The outcomes are discussed.