Effect of replacing SiO2 by ZnO on the physical properties of aluminosilicate glasses

Abstract

The effect of replacing SiO2 by ZnO was studied in aluminosilicate glasses containing alkaline earth oxides or lanthanum oxide with respect to the molar volume V1, the molar refraction RM, the Vickers microhardness Hv, the coefficient of linear thermal expansion A and the transformation temperature Tg. Nearly constant V1 and RM values are observed with increasing ZnO content and indicate that there is no change in the space filling degree of the network structure. Here ZnO may be regarded as a network former. Hv and A increase slightly with the addition of ZnO, where the extent of the increase depends on alkaline earth oxide. In contrast Tg values decrease with the addition of ZnO for all types of alkaline earth oxides. Therefore, it can be concluded that the incorporation of ZnO effects a decrease of viscosity in the transition temperature range.