EPR study of vanadyl ions in Li2O-MoO3-B2O3 glasses

Electronic paramagnetic resonance (EPR) spectra of xLi2O·(30 minus x)MoO3·70B2O3 glasses (0 le x le 25) containing 2 mol% V2O5 were studied between room and liquid-helium temperatures at X-band frequencies. The spectra are typical of V4+ ions present in vanadyl (VO2+) form in the glass. The spin-Hamiltonian parameters (SHP), gparallel gperpendicular, Aparallel, and Aperpendicular, the dipolar hyperfine coupling parameter, P, and the Fermi constant interaction parameter, k, were evaluated. It was found that these parameters are independent of the temperature. Results suggest that the tetragonal distortion of the V4+O6 complex increases with increase in the Li2O:MoO3 ratio. It was also found that the increase in this ratio results in an expansion of the 3dxy orbit of unpaired electrons in the vanadium ion and that the spin-Hamiltonian parameters do not depend on the value of theoretical optical basicity