Electron paramagnetic resonance studies of Bi2O3-Li2O-As2O3-B2O3 glasses doped with vanadium

Electron paramagnetic resonance studies of the xBi2O3−(30-x)Li2O-10AS2O3−58B2O3 (where x=5, 10, 15, 20 and 25 mol%) containing 2 mol% V2O5 as the paramagnetic probe were carried out at room temperature. These glasses were prepared using conventional melt quenching. The amorphous nature of the prepared glass samples was confirmed by x-ray diffraction studies. From the EPR spectra, the spin-Hamiltonian parameters (SHP) of VO2+ ions, dipolar hyperfine parameter (P) and Fermi contact interaction parameter (K), molecular orbital coefficients (α2 and γ2), the number of spins participating in the resonance (N), and susceptibility (χ) have been evaluated. From the spin-Hamiltonian parameters, it was concluded that the vanadyl ions exist as VO2+ ions in octahedral coordination with tetragonal compression with C4V symmetry and the ground state is dxy. Tetragonality (Δg||/Δg1) of V4+ ion sites exhibited nonlinear variation in the glass composition in all the glasses studied. Further, the theoretical optical basicity of the glasses has also been evaluated and it is observed that the changes in optical basicity values are in accordance with the changes in SHPs.