Theoretical studies of the optical and EPR spectra for Fe3+ ion in the MF3:Fe3+ (M=Al, Ga) systems

Abstract

By analyzing the EPR spectra of Fe 3+ ion in the fluorinde glasses, the local lattice structures around impurity Fe 3+ ion in MF 3 :Fe 3+ (M=Al, Ga) systems have been studied by means of diagonalizing the complete energy matrices of the electron–electron repulsion, the ligand-field and the spin–orbit coupling for a d 5 configuration ion in a trigonal ligand-field. Both the second-order and fourth-order EPR parameters D and ( a − F ) are taken simultaneously in the structural investigation. The results indicate that the local lattice structure around octahedral Fe 3+ center has an expansion distortion for Fe 3+ in MF 3 :Fe 3+ (M=Al, Ga). The expansion distortion may be ascribed to the fact that the radius of Fe 3+ ion is larger than that of Al 3+ ion and Ga 3+ ion, and the Fe 3+ ion will push the fluoride ligands upwards and downwards, respectively. The local lattice structure parameters R= 1.927 A, θ =55.538° for Fe 3+ in AlF 3 :Fe 3+ and R =1.931 A, θ =56.09° for Fe 3+ in GaF 3 :Fe 3+ are determined, respectively, and the EPR spectra of the MF 3 :Fe 3+ (M=Al, Ga) systems are satisfactorily explained.