Properties of lithium aluminoborate glasses

The density, refractive index, thermal expansion coefficient, glass transformation temperature and d.c. conductivity have been determined for a number of lithium aluminoborate glasses. The glasses studied lie on lines of constant Al2O3 to Li2O concentration with values of 0 (binary lithium borate glasses), 1/2 and 1/1. The thermal expansion coefficient passes through a minimum for all three series of glasses, while the glass transformation temperature for each series passes through a maximum. This behaviour is characteristic of the borate anomaly for all three series of glasses. Replacement of B2O3 by Al2O3 in these glasses has only a slight effect on the density and refractive index. The d.c. electrical conductivity of these glasses is controlled by the Li2O concentration, with little change due to replacement of B2O3 by Al2O3.