Chapter 14: Rare Earths in Germanate Glasses Check Access

Binary rare earth germanate glasses containing La₂O₃ are phase separated for glasses containing less than 15 mol% La₂O₃. The density and refractive index increase with increasing La₂O₃ concentration, while two values of T_g are present for the glasses within the phase separated region. Property studies of ternary germanate glasses containing La₂O₃ and either BaO, B₂O₃, Ga₂O₃, ZrO₂ or Ta₂O₅ reveal that the density and refractive index increases with increasing Ta₂O₅ concentration and decrease with increasing B₂O₃ concentration. The density and T_g of rare earth aluminogermanate and gallogermanate glasses increase with increasing atomic number of the rare earth ion present. The refractive indices of these glasses lie in the range of 1.7 to 1.9. These glasses exhibit very low electrical conductivities and very high chemical durabilities and hardnesses. The magnetic susceptibility and Verdet coefficient vary with the identity of the rare earth ion present. Ternary germanate glasses containing Na₂O and a rare earth oxide exhibit small glassforming regions, with property trends similar to those of the other glasses containing rare earth oxides.