Ti³⁺-Free Titanophosphate Glasses as Eco-Optical Glasses

Abstract

The glasses containing a large amount of TiO₂ are considered as eco-optical glasses with high refractive index and low density. In the present work, the phosphate glasses with high TiO₂ content, which have been developed as electronic conduction glasses and are black in color due to the inclusion of relatively large amount of Ti³⁺ ions, were attempted to be made applicable as novel eco-optical glasses. Colorless and transparent Ti³⁺-free titanophosphate glasses (60-74 mol% TiO₂) were successfully obtained by re-heat-treating the black glasses near glass transition temperature in the air. Binary glasses thus obtained possessed high refractive index (1.8-2.0), high dispersion and low density (3.0 g•cm^-3 at most). Furthermore, the Abbe number, glass transition temperature and thermo-optic coefficient were modified by the introduction of La₂O₃, ZnO and K₂O, respectively, into the 60TiO₂•40P₂O₅ glass.