Influence of ion distribution on the ionic conductivity of lithium tellurite glasses (Li 2OTeO 2 and LiFTeO 2)

Abstract

TeO 2 forms stable glasses with Li 2O and LiF in a large range of compositions (from 0.45 to 0.9 in molar ratio of TeO 2). The ionic conductivity of these glasses is measured as a function of temperature and chemical composition by the complex impedance method (frequency range: 10 −2 −10 4 Hz, temperature range: 100°C− T g_. A parallel study by 7Li- and 19F-NMR spectroscopy allows identification of Li + ions as the carriers responsible for the ionic conductivity of these solids. From the second moment of NMR signals, two different distributions of lithium are proposed: one in which Li + ions are dispersed in Li 2OTeO 2 glasses and another one, in which Li + and F − ions are associated in the network of LiFTeO 2 glasses. These distributions are correlated with ionic conductivity results.