Dependence of properties on structural units in Li2O-Al2O3-SiO2 glasses

Density, thermal expansion coefficient, transformation temperature and elec trical resistivity have been investigated for (33-x)Li2O.xAl(2)O(3).67SiO(2 ) glasses. There is a marked change in all these properties for Al2O3/Li2O >1. The change is correlated to the formation of AlO6 units. Some change wa s observed in the thermal expansion coefficient, transformation temperature and electrical conductivity at Al2O3/Li2O approximate to0-5. At this ratio there would be an equal number of Q(4)-AlO4 and Q(4)-Q(3) linkages. When i ncreasing Al2O3 content the thermal expansion coefficient decreases and the transformation temperature increases. It is deduced that the network becom es more crowded with the structural units in spite of the increase in molar volume. A maximum in both electrical resistivity), and activation energy i s observed at Al2O3/Li2O approximate to0.5. It is attributed to changes in the concentration and mobility of the Li+ ions belonging to the AlO4 and Q( 3) units.