Theoretical studies of local structures and spin hamiltonian parameters for Cu2+ in alkali barium borate glasses

The local structures and spin Hamiltonian parameters are theoretically studied for Cu2+ in alkali barium borate glasses 20A2O ∙ 24.5BaO · 55B2O3 · 0.5CuO, where A = Li, Na and K by the quantitative calculations of these parameters for tetragonally elongated octahedral 3d9 clusters. The [CuO6]10‒ clusters are subject to the local relative tetragonal elongation ratios 7.8, 8.1 and 8.4% in Li, Na and K barium borate glasses, respectively, owing to the Jahn–Teller effect. The increasing (Li < Na < K) local relative elongation ratio and decreasing cubic field parameter and covalency factor are discussed in a consistent way.