Role of PbO in EPR, optical properties and DC conductivity of vanadyl-doped alkali lead borate glasses

Glasses with composition xM2O (0.30−x) PbO 0.70 B2O3 (M=Li, K) containing 2.0 mol% of V2O5 have been prepared in the range 0.00⩽x⩽0.15 by normal melt quenching method. Electron paramagnetic resonance (EPR), optical properties and DC conductivity of these glasses have been studied. Spin Hamiltonian parameters (SHPs), dipolar hyperfine parameter, P and Fermi contact interaction parameter, K and molecular orbital coefficients (α2 and γ2) have been calculated. In these glasses there is an increase in the tetragonality of the V4+O6 complex and the 3dxy orbit expands with an increase in the M2O:PbO ratio. Values of the theoretical optical basicity, Λth, have also been reported. Optical band gap increases with decrease in PbO content. For x>0.02, the DC conductivity of these glasses increases and activation energy decreases.