CALCIUM GALLIOSILICATE GLASSES

The glassforming region has been determined for the calcium galliosili cate system. These glasses are less refractory than the corresponding calcium aluminosilicate glasses and are more prone to phase separation . The density, refractive index and thermal expansion coefficient are higher than those of the corresponding aluminosilicate glass. In gener al, differences between the properties of calcium galliosilicate and a luminosilicate glasses can be explained on the basis of differences be tween the mass and radius of the gallium and aluminium ions. However, differences in behaviour between the galliosilicate and aluminosilicat e glasses at low silica concentrations cannot be explained using the e xisting model for the role of calcium in the structure of low silica g lasses.