Study of electron paramagnetic resonance, optical transmission and dc conductivity of vanadyl doped Bi 2O 3·B 2O 3·Li 2O glasses

Abstract

Glasses with composition xBi 2O 3·(70− x)B 2O 3·30Li 2O containing 2 mol% V 2O 5 have been prepared over the range 0≤ x≤20 (in mol%). The electron paramagnetic resonance (EPR) spectra of VO 2+ ions of these glasses have been recorded in the X-band (≈9.13 GHz) at room temperature. Spin Hamiltonian parameters (SHP), g ||, g ⊥, A ||, A ⊥, dipolar hyperfine coupling parameter, P, and Fermi contact interaction parameter, K, have been calculated. The molecular orbital coefficients, α 2 and γ 2, have been calculated by recording the optical transmission spectra in the wavelength range of 500–850 nm. It has been observed that the octahedral symmetry around V 4+ ion is improved, and the 3d xy orbit of the unpaired electron of the vanadium ion expands with increase in Bi 2O 3:B 2O 3 ratio. Values of the theoretical optical basicity, Λ th, have also been reported. The dc conductivity increases with an increase in temperature. The dc conductivity variation with Bi 2O 3 content shows mixed glass-former effect at x=8 mol%. For x=10 mol%, the conductivity decreases with increase in Bi 2O 3 content because of the decrease in the mobility and the number of Li + ions available for the conduction.