Investigations of the optical and EPR spectral data for the trigonal Cr3+ center in ZnGa2O4: Cr3+ crystal with a unified method-complete diagonalization of energy matrix

Abstract

The optical and EPR spectral data of the trigonal Cr3+ centers in ZnGa2O4: Cr3+ crystal are unifiedly calculated by applying the complete diagonalization of energy matrix method resting on the two-spin-orbit-parameter model, where the one-electron basis functions are the molecular orbitals and the contributions from both the spin-orbit parameters of dn ion and ligand ion are included. Thus, the Racah parameters B, C, two spin-orbit parameters and two orbit reduction factors can be evaluated from a adjustable parameter, the covalence factor, and so only three adjustable parameters are used in the calculation. The ten calculated spectral data (seven optical band positions and three EPR parameters, g factors g//, g⊥ and zero-field splitting D) are rationally consistent with the experimental values. The defect structure of the trigonal Cr3+ center is also given. These outcomes are discussed.