Electron paramagnetic resonance and optical absorption studies on vanadyl doped alkali tetraborate glasses

Abstract

Electron paramagnetic resonance (EPR) and optical absorption studies have been made for VO(II) ions in alkali tetraborate glasses. The EPR spectrum shows eight hyperfine lines characteristic of VO(II) ions. The spin-Hamiltonian parameters, Fermi contact interaction parameter K, dipolar hyperfine coupling parameter P have been evaluated from the spectra. The anisotropy energy of the VO(II) ions have also been calculated. The values of the spin-Hamiltonian parameters confirm that V 4+ ions are present in the glasses as VO(II) molecular ions in an octahedral site with a tetragonal compression. The theoretical values of optical basicity (^ th) of glasses have also been evaluated. The optical absorption spectra of VO(II) ions in these glasses show two bands corresponding to the transitions 2B 2g → 2B 1g and 2B 2g → 2E g in the order of decreasing energy respectively. By correlating the electron paramagnetic resonance data and optical data, the molecular orbital coefficients have been evaluated.