Effect of Bi2O3 on electron paramagnetic resonance, optical transmission and conductivity in vanadyl-doped Bi2O3·K2O·B2O3 glasses

Glasses with composition xBi2O3·(30−x)K2O·70B2O3 doped with 2 mol% of V2O5 have been prepared over the range 0≤x≤15 (in mol%). The electron paramagnetic resonance spectra of VO2+ in these glasses have been recorded in the X-band (≈9.3 GHz) at room temperature. The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that, with increase in Bi2O3:K2O ratio, tetragonal distortion of the V4+O6 complex increases and there is an expansion of the 3dxy orbit of unpaired electron in the vanadium ion. The values of theoretical optical basicity have also been reported. The molecular orbital coefficients have been calculated by recording the optical transmission spectra in the wavelength range 500–850 nm. The direct-current electrical conductivity, σ, has been measured in the temperature range 443–523 K. σ decreases with increase in Bi2O3:K2O ratio because of the decrease in the mobility and number of mobile K+ ions and there is no electronic contribution to the conductivity by Bi2O3.