Theoretical studies of spin Hamiltonian parameters for the tetragonally elongated Cu2 + centers in ARbB4O7 (A = Li, Na, K) glasses

The spin Hamiltonian parameters (g factors g||, g⊥ and the hyperfine structure constants A||, A⊥) for the Cu2 + centers in ARbB4O7 (A = Li, Na, K) glasses were theoretically studied based on the high-order perturbation formulas of these parameters for a 3d9 ion in a tetragonally elongated octahedron. In these formulas, the contributions to the g factors from the tetragonal distortion, characterized by the tetragonal field parameters Ds and Dt are taken into account by considering the relative axial elongation of the ligand octahedron around the Cu2 + due to the Jahn–Teller effect. Based on the calculations, the ligand octahedra around Cu2 + are suggested to suffer about 6.8%, 8.9% and 12.3% relative elongation along C4 axis for LiRbB4O7, NaRbB4O7, and KRbB4O7 glasses, respectively, and a negative sign for A|| and A⊥ for these Cu2 + centers was suggested in the discussion.