Investigations on the local structure and the spin Hamiltonian parameters for Cu2+ in xCuO-(68-x)V2O5-32TeO2 glasses

The defect structure, spin Hamiltonian parameters (SHPs: anisotropic g factors g(parallel to) and g(perpendicular to) and the hyperfine structure constants A(parallel to) and A(perpendicular to)), and their compositional dependence of Cu2+ in xCuO - (68 - x) V2O5 - 32TeO(2) (x = 5, 10, 20, 30 mol%) glasses are quantitatively analyzed by using the higher-order perturbation formula of octahedral complex with tetrahedral elongation distortion. Due to the Jahn-Teller effect, the [CuO6](10-) group is subjected to tetragonal elongation distortion of varying degrees. D-q, N, rho, kappa, and H show nonlinear changes with the concentrations of Cu2+. When x = 10 mol% CuO, the degree of distortion (rho approximate to 0.1%) is the smallest; when x = 30 mol% CuO, the degree of distortion (rho approximate to 15%) is the largest, which indicates that excessive distortion leads to the appearance of Z-axis oxygen vacancies and the coordination number of copper ions from six to four. The increasing tendency of the evaluated N and H reveals decreasing covalency of the whole glass system. Present theoretical studies would be useful to the explore the structural properties and optical applications of glass with different CuO concentrations.