Structural, Optical and Dielectric Properties of Tellurite Borate Glasses Doped with Cerium Oxide

Synthesis of tellurite borate (35-x) TeO2 + 35 B2O3 + 20 Bi2O3 + 10 Li2O + x CeO2 and x = 0, 0.5, 1.5, 3 mol% glasses have been achieved by using the melt quenching technique. Density, X-ray diffraction (XRD), Raman spectroscopy measurements and UV–Vis analysis were measured. Dielectric measurements were recorded in the frequency range of 100 Hz–100 kHz at room temperature. XRD patterns of all the investigated glass samples doped with CeO2 are completely amorphous. Densities of the prepared glasses increased from 4.80 to 4.89 g/cm3 and molar volumes decreased from 36.74 to 36.14 cm3/mole. Raman spectroscopy reveals that the Raman intensity increases with increasing substitution of CeO2 by TeO2. UV–Vis analysis reveals that a higher CeO2 substitution ratio increased the absorbance and optical properties of produced glass samples. The CeO2 content of tellurium borate glass samples were found to affect all of the optical characteristics. With increasing CeO2 concentration, the optical energy gap decreases (Egopt\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(E_{g}^{opt}$$\end{document}) from 2.77 to 1.96 eV for direct allowed transitions and from 2.45 to 1.82 eV for indirect allowed transitions. It has also been studied how electrical conductivity and dielectric properties change with frequency and composition. Values ε′, ε″ and σac of sample with x = 0 are greater than those values of with x = 3. The variation of the imaginary part of the electric modulus (M″) versus frequency (F) plot curve is asymmetric of non-Lorentzian type. A shift of the frequency peak towards the higher frequency region was observed by increasing CeO2 mol%.