Effect of Li2O content on structural and optical properties of Li2O-TeO2-As2O3-B2O3 glasses

Abstract

Arsenate-based alkali borotellurite glasses with the general formula xLi2O-(30−x)TeO2-10A2O3-60B2O3, where 5 ≤ x ≤ 25, were formulated by the conventional melt quenching technique. The glassy nature of the samples was confirming by X-ray diffraction measurements. The influence of Li2O content on the Fourier transform IR, optical, and thermal properties, density, and other related properties of the prepared glasses was studied. The results reveal that the density and molar volume decrease and the glass transition temperature increases with increasing Li2O content This can be attributed to the difference in the ionic radii of lithium and tellurium oxides. The variation in the indirect optical bandgap and band tail with Li2O content is discussed in relation to the glass structure. On the basis of the values obtained for αO2−, the optical basicity, and the interaction parameter, the present glasses were termed normal ionic (basic) glasses. Fourier transform IR spectroscopy of the present glasses revealed that the borate network is affected by the replacement of TeO2 by Li2O. It was found that the fraction of four-coordinate boron atoms decreases and the fraction of three-coordinate boron atoms increases with increasing Li2O content.