EPR and Optical Properties of Alkali Halo Cadmium Borate Glasses Containing Vanadium Ions

The glass composition x NaF-(40-x) CdO-58B(2)O(3)-2V(2)O(5) with (x=5, 10, 15, 20, 25, 30 & 35 mole %) have been prepared by melt quenching technique. Glasses are characterized by XRD, EPR and UV -Visible spectra. No characteristic peaks are found in XRD spectra revealing the amorphous nature of prepared glasses. Spin -Hamiltonian parameters g(parallel to), g(perpendicular to), A(parallel to), A(perpendicular to) bonding parameters (1-alpha(2)), (1-gamma(2)), Fermi contact interaction parameter (K), dipolar hyperfine coupling parameter (P), number of spins (N) and paramagnetic susceptibility (chi) were calculated. It was observed that these parameters are varying nonlinearly with increasing NaF concentration. From the spin Hamiltonian parameters it is confirmed that vanadium ions exist as VO2+ ions with octahedral co-ordination with tetragonal compression with C-4v symmetry and the ground state is being dxy. Optical absorption spectra of VO2+ ions in the present glass samples had shown two transitions correspond to B-2(2g) -> B-2(1g), B-2(2g)-> E-2(g). Optical band gap, Urbach energy and refractive index values are varying non -linearly with increasing NaF concentration.