Study of EPR, optical properties and electrical conductivity of vanadyl doped Bi2O3·PbO·B2O3 glasses

Heavy metal based oxide glasses having composition xBi2O3·(0.30 − x)PbO·0.70B2O3 have been prepared (0.00 ≤ x ≤ 0.15, mol%) containing 2.0 mol% of V2O5 by normal melt-quenching technique. Electron paramagnetic resonance (EPR), optical spectra and dc conductivity of these glasses have been studied. Spin Hamiltonian parameters (SHP) of VO2+ ions, dipolar hyperfine parameter, P and Fermi contact interaction parameter, K, molecular orbital coefficients (α2 and γ2) and optical band gap have been calculated. It is observed that in these glasses, the tetragonal nature of V4+O6 complex increases with Bi2O3 content. Increase in Bi2O3:PbO ratio results in the contraction of 3dxy orbit of the unpaired electron in the vanadium ion, and the SHP are dependent on the theoretical optical basicity, Λth. In present glasses, the conductivity (activation energy) first decreases (increases) with increase in mol% of Bi2O3 content upto x = 0.08 and then shows a maxima (minima) at x = 0.10 and then starts decreasing (increasing) upto x ≤ 0.15 with mol% of Bi2O3 content.