Tellurite Glasses

JSGT 1952 V36 T217-T241

Consideration of the electronegativity values of the elements leads to the conclusion that lead oxide–tellurium oxide and barium oxide–tellurium oxide mixtures may well form glasses of high refractive index and low softening point. A barium tellurite glass has a refractive index of 2·08, a deformation temperature of 326°, a linear thermal expansion coefficient of 191×10^-7 cm/cm/°, and a dielectric constant of 25, all values of unusual interest. Lead tellurite glasses have similar properties, with refractive index values up to 2·25. Many three component glasses are reported containing TeO₂, PbO or BaO and one of the following: Li₂O, Na₂O, B₂O₃, Cb₂O₅, P₂O₅, MoO₃ , WO₃, ZnF₂, V₂O₅, MgO, CdO, TiO₂, GeO₂, ThO₂, Ta₂O₅, La₂O₃. Some of these glasses have remarkably good infra-red transmission at least to 5·5 µm.

J. E. Stanworth