Synthesis, characterization and AC conductivity of alkali metal substituted telluride glasses

A glass system 0.70TeO2·(0.30-x) Na2O·xK2O with 0 ≤ x ≤ 0.3 was prepared using Quenching method. The structural, optical and electrical properties of these compositions were investigated. The structural analysis indicated that these glasses are composed of structural units of TeO3, TeO4, TeO3 + d and TeOTe. The optical band gap of the investigated glasses was found to lie between 3.43 and 3.74 eV range. With the increasing content of K2O, the values of density, molar volume, optical basicity, refractive index, molar refractivity, electronic polarizability and electric susceptibility were found to increase, whereas Urbach energy and oxygen packing density decreased. The ion dynamics in these glass systems were studied using Dyre's free energy barrier model and Jonscher Power Law. The conductivity data followed both the models. The scaling behaviour of the two glass systems was studied using Ghosh and Dyre's scaling models. The conductivity spectra were found to follow the Dyre's scaling law, however, surprisingly, the spectra were failed to follow the Ghosh scaling law.