Calculations with the two-mechanism model for the spin-Hamiltonian parameters of Mo5+ ions in phosphate glasses

The high-order perturbation formulas based on the two-mechanism model are used to calculate the spin-Hamiltonian parameters (g factors g(parallel to), g(perpendicular to) and hyperfine structure constants A(parallel to), A(perpendicular to)) of the tetragonal Mo5+ centers in phosphate glasses xMoO(2)center dot(100 - x)[2P(2)O(5)center dot Na2O]. In the calculations, not only the crystal-field (CF) mechanism concerning CF excited states in the widely-applied CF theory, but also the charge-transfer (CT) mechanism concerning CT excited states (which is often omitted) is taken into account. The calculated results are close to the experimental values. The calculations show that the contributions Delta g(i)(CT) (= g(i) - g(e), where g(e) approximate to 2.0023) and A(i)((2)CT) due to CT mechanism in sign are contrary to the corresponding Delta g(i)(CF) and A(t)((2)CF) due to CF mechanism, and the values of relative importance vertical bar Q(CT)/Q(CF)vertical bar of CT mechanism are about 19%, 17%, 8% and 13% for Q = Delta g(parallel to), Delta g(perpendicular to), A parallel to((2)) and A(perpendicular to)((2)). It appears that in the complete and exact calculations of spin-Hamiltonian parameters for the high valence state d(n) ions (e.g., Mo5+ considered here) in crystals, one should take into account the two (CF and CT)-mechanism model. (C) 2013 Elsevier B.V. All rights reserved.