Thermal, optical and spectroscopic studies of boro-tellurite glass system containing ZnO

Abstract

A series of stable and transparent glasses with the composition (72–0.5x)TeO2–(27.5–0.5x)B2O3–xZnO–0.5V2O5 (x=0, 6, 12, 18, 24 and 30mol%) were prepared by melt quenching technique. These glasses were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, differential scanning calorimetry (DSC), EPR and optical absorption. XRD and DSC analysis confirmed the glassy nature of the prepared samples. The physical properties such as density (ρ), molar volume (Vm) and oxygen packing density (OPD) were calculated. FTIR and Raman studies showed that the glass network consists of TeO3, TeO3+1, TeO4, BO3 and BO4 units. These studies also revealed that TeO4 units transform into TeO3 units and BO4 into BO3 units with the addition of ZnO content at the expense of both B2O3 and TeO2 glass forming oxides. From DSC, it was found that the glass transition temperature (Tg) increases with the increase of ZnO content. The thermal stability (ΔT=To−Tg) of the sample with ZnO of 30mol% was found to be maximum (166°C).The optical band gap energy (Eopt) and Urbach energy (∆E) values of the glass system were calculated using the optical absorption data. Using electron paramagnetic resonance (EPR) spectra of the present glasses the spin Hamiltonian parameters of VO2+ ions were calculated.