Chapter 5: Germanate Glasses Containing Conditional Glassformers Check Access

The oxides of As, Sb, Bi, Te, and V, which are called “pseudoglassformers”, form binary glasses with GeO₂ over significant compositional ranges. Since these glasses contain toxic components, proper care must be taken in their preparation. All these oxides increase the molar volume, refractive index, molar refractivity, and thermal expansion coefficient, while, with the exception of Bi₂O₃, they decrease the T_g of the glass. There are only a few studies of ternary germanate glasses containing both a modifier oxide and a pseudoglassformer. In every case, the addition of equimolar concentrations of the modifier oxide and the pseudoglassformer increases the density and refractive index. The antimony bismuth germanate glasses are the only germanate glasses containing two pseudoglassformers where property data are available. The density and refractive index of these glasses increase as the GeO₂ concentration decreases. Tables of the best values of the densities and refractive indices of the binary and ternary glasses are included.