Raman, DSC, ESR and optical properties of lithium cadmium zinc tellurite glasses

The glasses with composition 64TeO2-15ZnO-(20−x)CdO-xLi2O-1V2O5 (0≤x≤20 mol%) were prepared by conventional melt quenching technique. X-ray diffraction was used to confirm the amorphous nature. The optical absorption studies revealed that the cut-off wavelength decreases while optical energy gap (Eopt) and Urbach energy (ΔE) values increase with an increase of Li2O. Refractive index (n) evaluated from Eopt was found to decrease with increase of Li2O content. The physical parameters such as density (ρ), molar volume (Vm) and oxygen packing density (OPD) have been analyzed and discussed. The electron paramagnetic resonance (EPR) spectra of VO2+ glasses have been recorded on X-band (v=9.14GHz) at room temperature. The spin Hamiltonian parameters of VO2+ ions have been calculated. It has been found that V4+ ions in these glasses exist as VO2+ in octahedral coordination with a tetragonal distortion. Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1/TeO3 and ZnO4 units as basic structural units. The glass transition temperature (Tg), onset crystallization (To) and thermal stability (ΔT) were determined from Differential Scanning Calorimetry (DSC).