The complete high-order perturbation formulas based on a 2-mechanism model for the spin-Hamiltonian parameters (g-factors and zero-field splitting) of 3d3 ions in trigonal octahedral sites were derived. In the model, not only the conventional contribution to spin-Hamiltonian parameters from the crystal-field mechanism, but also that from the charge-transfer mechanism (which was omitted in the crystal-field theory) were included. From these formulas, the spin-Hamiltonian parameters of Mn4+ replacing Al3+ in Al2O3 crystal were calculated by using the parameters related to the optical spectral data and the defect structure of the studied system. The results (including the relative importance of the charge-transfer mechanism on the spin-Hamiltonian parameters and the defect structure of Mn4+ impurity center) were considered.

Investigations of Spin-Hamiltonian Parameters and Defect Structure for Mn4+ in Al2O3 from a Two-Mechanism Model. X.X.Wu, W.L.Feng, W.Fang, W.C.Zheng: Physica Status Solidi B, 2008, 245[4], 756-60