Refractive index and density of alkali lime borogermanosilicate glasses

Abstract

Refractive index and density data of glasses having molar compositions 15% A2O-10% CaO-45% SiO2-(30−x%) GeO2-x% B2O3 with A=Na or K are reported. From these data the molar refraction and the contribution of oxygen to the molar refraction are calculated. The co-ordination of germanium and boron in these glasses is discussed. At x=0, GeO6 octahedra are observed which are gradually transformed into GeO4 tetra-hedra as the GeO2 is replaced by B2O3. In B2O3-rich glasses no GeO6 octahedra are present and the structure of the B2O3-rich glasses is found to be the same as that of comparable alkali borosilicate glasses.