Investigations on the local structure and the spin Hamiltonian parameters for Cu²⁺ in xCuO-(68-x)V₂ O₅ -32TeO₂...

The defect structure, spin Hamiltonian parameters (SHPs: anisotropic $$ factors $$ and $$ and the hyperfine structure constants $$ and $$ ), and their compositional dependence of $$ in $$ ( $$ = 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 $$ group is subjected to tetragonal elongation distortion of varying degrees. $$ , and $$ show nonlinear changes with the concentrations of $$ . When $$ = 10 mol% CuO, the degree of distortion ( $$ ) is the smallest; when $$ = 30 mol% CuO, the degree of distortion ( $$ ) is the largest, which indicates that excessive distortion leads to the appearance of $$ -axis oxygen vacancies and the coordination number of copper ions from six to four. The increasing tendency of the evaluated $$ and $$ reveals decreasing covalency of the whole glass system. Present theoretical studies would be useful to the explore the structural properties and optical applications of glass with different $$ concentrations.