Theoretical Studies of the Electron Paramagnetic Resonance Parameters and Local Structure for VO~(2+) in Oxyfluoroborate Glasses

摘要

The electron paramagnetic resonance parameters (g factors g_(II), g and hyperfine structure constants A_(II), Ai_) of a tetragonal V~(4+) center in oxyfluoroborate glasses (20Li2O-10Li2F2-70B2O3) are theoretically investigated by using the perturbation formulas for a 3d~1 ion in tetragonally compressed octahedra. The calculated results are in good agreement with the experimental data. Local structure parameters of [VO6]~(8-) clusters are obtained from the calculation (i.e., R_(II) ≈ 1.74 A and R ≈ 1.985 A for the metal-ligand distances parallel and perpendicular to the C4 axis, respectively). It is shown that the local structure around the V~(4+) ion possesses a compressed tetragonal distortion along Cn axis. The signs of the hyperfine structure constants A_(II) and A for V~(4+) centers in oxyfluoroborate glasses were also suggested in the discussion.