Refractive Indices of Glasses of CaO-Ga2O3-GeO2 System

The results for the refractive indices of undoped and Nd- and Ce-doped glasses of CaO-Ga2O3-GeO2 system are obtained and analyzed. The glasses with the garnet (Ca3Ga2Ge3O12) and Ca-gallogermanate (Ca3Ga2Ge4O14) compositions have been obtained by high-temperature synthesis. Nd and Ce impurities have been added to the garnet-composition glass as Nd2O3 and Ce2O3 oxides in the amounts of 0.2 and 0.7 wt. %, respectively. The refractive indices of the glasses depend on the basic glass composition. In particular, the refractive index increases with increasing Ge content. The presence of Nd and Ce impurities in the garnet-composition glasses in the amounts larger than 0.1 wt. % gives rise to essential increase of the refractive indices. The average refractive indices for the glasses with Ca3Ga2Ge4O14 composition are considerably smaller than those of the corresponding crystals with the garnet and Ca-gallogermanate structure. Significant deviations of the refractive index measured in different parts of Ca3Ga2Ge3O12 garnet crystal can be related to inhomogeneous distribution of Ge.