Research on the Spin-Hamiltonian Parameters and Local Structure for the Tetragonal Mo5+Centers in CaWO4Crystal

Abstract

The spin-Hamiltonian parameters (g factors g‖, g⊥ and hyper ne structure constants A‖(A), A⊥(A), A‖(B) and A⊥(B), A(A) and A(B) belonging to isotopes Mo and Mo) of Mo ion at the tetragonally-compressed tetrahedral W site in CaWO4 crystal are calculated from the high-order perturbation formulae based on the two-mechanism model, where besides the contributions to spin-Hamiltonian parameters due to the crystaleld mechanism concerning the crystaleld excited states in the extensively-applied crystaleld theory, those due to charge-transfer mechanism concerning charge-transfer excited states (which are omitted in crystaleld theory) are included. The calculated results are in reasonable agreement with the experimental values. The calculations show that for the high-valence state d ions (e. g., Mo considered) in crystals, the contributions due to charge-transfer mechanism should be taken into account in the studies of spin-Hamiltonian parameters. The local structure of Mo center in CaWO4 crystal due to the impurity-induced local lattice relaxation is estimated from the calculations. The results are discussed.