Mixed former effect between TeO2 and SiO2 in the Li2O·TeO2·SiO2 system

Glass samples of the 0.30Li2O·0.70(xTeO2·(1−x)SiO2) system were synthesized. The difference between the melting points of silica and tellurium oxide, which melts at 733°C with further volatilization, makes this synthesis a complex one. However, transparent and homogeneous glasses were obtained in the SiO2-rich domain up to x=0.30 by mixing appropriate amounts of the two binary systems, 0.30Li2O·0.70SiO2 and 0.30Li2O·0.70TeO2, in an induction furnace. With the increase of the TeO2 content in the samples investigated a decrease of Tg and an increase in the samples’ densities were measured. The results of electrical measurements, carried out by impedance spectroscopy, show an increase in electrical conductivity when TeO2 is added to the Li2O·SiO2 glass, which we attribute to a mixed former effect between TeO2 and SiO2. Both the activation energy and the σ0 parameter of the Arrhenius equation increase with increased TeO2 content in the samples. A carbon replica analysis of the samples shows a phase separation in the ternary glasses.