EPR studies of strontium alkali borate glasses doped with vanadium

Electron paramagnetic resonance (EPR) studies were made on 10Li(2)O-10Na(2)O-10K(2)O-xSrO-(68-x)B2O3-2V(2)O(5) glasses. The glasses were prepared by the conventional melt quenching method and amorphous nature of the glass samples was confirmed by x-ray diffraction. From the EPR spectra the spin -Hamiltonian parameters were evaluated. It was observed that the V4+ ions are present as VO2+ vanadyl ions in octahedral coordination with tetragonal compression and belong to C-4v symmetry, with d(xy) ground state. The measure of tetragonality Delta g(parallel to)/Delta g(perpendicular to) varies in a nonlinear manner with SrO content which may be due to change in the ligand field strength at the site V4+ ion site. The covalency rates indicated moderate covalency for the sigma- and pi-bonds. The number of spins participating in the resonance (N) and susceptibility (chi) were evaluated, and found to vary with SrO content.