Impedance analysis of TeO2-SeO2-Li2O nano glass system

Abstract

Nano crystallization in tellurium selenite glasses (TeO2-SeO2-Li2O) is achieved by the conventional heat treatment method. The structural phase transformation of glass samples is verified by X-Ray diffraction. The morphology, crystallinity, and the size of crystals were determined by Field Emission Scanning Electron Microscopy. The main crystalline phases detected are Li2Te2O5|α- Li2Te2O5, TeO2, Li2TeO3, SeO2, Li2Te2O5|β - Li2Te2O5, Se. It is found that nanoparticles are agglomerated into a rod-like structure having size in the range of 20–93 nm. Conduction mechanism and relaxation behavior in the present glass system is studied with a function of temperature and frequency. The conductivity is slightly increased from 1.04 × 10−4 to 2.87 × 10−4 Ω−1m−1 as the temperature is increased from 100 to 250 °C. It is observed that the electrical resistance decreases as the Li2O concentration is increased from 10 to 20 mol %. From the modulus spectra, the presence of both grain and grain boundary effect is observed. From the data, the hump is observed around temperature 200 °C in the tested glass system and indicates transition which represents resonance in the glass system due to nano crystalline behavior in the glass matrix. The power law exponent is calculated by fitting the data and suggesting those ideal long-range pathways, diffusion-limited hopping in the glass sample. Based on exponent values, ionic conductivity exists in the glass sample. Keywords: Nano crystallization, Nano glasses, Nanorods, Impedance analysis, AC and DC conductivity