Structural investigations of vanadyl doped Nb2O5•K2O•B2O3 glasses

Pottasium nioborate glasses of composition xNb(2)O(5)center dot(30-x)K2O center dot 69B(2)O(3) containing 1 mol % of V2O5 were prepared by melt quench technique (1473K, 1h). The electron paramagnetic resonance spectra of VO2+ in these glasses have been recorded in X- band (v approximate to 9.14 GHz) at room temperature (RT). The spin Hamiltonian parameters, dipolar hyperfine coupling parameters, P and Fermi contact interaction parameter, K have been calculated. It is found that V4+ ions in these glasses exist as VO2+ in octahedral coordination with a tetragonal distortion. The tetragonality of V4+O6 complex decreases with increasing Nb2O5:K2O ratio and also there is an expansion of 3d(XY) orbit of unpaired electron in the vanadium ion. The study of IR transmission spectra over a range 400- 4000 cm(-1) depicts the presence of both BO3 and BO4 structural units and Nb5+ ions are incorporated into the glass network as NbO6 octahedra, substituting BO4 groups.