Spectroscopic and dielectric properties of ZnF2–As2O3–TeO2 glass system doped with V2O5

ZnF2–As2O3–TeO2 glasses mixed with different concentrations of V2O5 (ranging from 0 to 0.6 mol%) were synthesized. The amorphous nature of these glasses was checked by X-ray diffraction and scanning electron microscopy techniques. A variety of properties, i.e. optical absorption, photoluminescence, infrared, ESR spectra and dielectric properties (constant ε′, loss tan δ, ac conductivity σac over a wide range of frequency and temperature) of these glasses have been explored. The optical absorption, electron spin resonance studies together indicated vanadium ions coexist in V4+ with V5+state in these samples. The IR spectra of these samples have exhibited bands due to νs-TeO2ax and AsO3 structural groups; these results indicated the most structural disorder in the network as the concentration of V2O5 is increased. Luminescent emission spectra recorded at room temperature of these glasses excited at 640 nm have exhibited a broad emission band in the spectral wavelength range of 750–850 nm. The luminescence efficiency is found to be the highest for the sample doped with 0.6 mol%. The dielectric parameters viz., ε′, tan δ and σa.c are found to increase and the activation energy for ac conduction is found to decrease with the increase in the concentration of V2O5 up to 0.6 mol%, reflecting an increase in the concentration of V4+ ions that take part modifying positions in the glass network. The ac conduction in these glasses could satisfactorily be explained by both classical activation energy and the tunneling phenomena.