Effect of intermediate oxide (Y2O3) on thermal, structural and optical properties of lithium borosilicate glasses

• Phase separation observed in glasses with modifier and intermediate oxides.
• Higher concentration of Y2O3 prevents the glass formation.
• Glass transition temperature and Urbach energy exhibited non-linear variation.

Glass and glass ceramic samples with composition 55SiO2–30B2O3–(x)Li2O–(15 − x)Y2O3, where x = 0, 5, 10, 15 are prepared by conventional melt-quench technique. The structural, physical, thermal, optical, mechanical and conducting properties of these glasses are studied using X-ray diffraction (XRD), Differential Thermal Analyzer (DTA), Fourier Transform Infrared spectroscopy (FTIR), UV–visible spectroscopy and Impedance spectroscopy. Theoretical elastic moduli are calculated for the better understanding of the glass network strength. All samples, except with x = 0 glass, are amorphous in nature. Two broad halos are observed in x = 5 and x = 10 glasses, indicating phase separation in these glasses. Optical band gap of the samples decreases with increasing Y2O3 content. The lowest band gap is observed ∼3.60 eV for x = 15 glass. Urbach energy increased with an increase in Y2O3 concentration. Y2O3 played different roles at different concentrations and enhanced the phase separation tendency in glass. The typical conductivity was observed ∼10−6 S/cm at 620 °C for x = 10 glass.