Ti3+‐Free Multicomponent Titanophosphate Glasses as Ecologically Sustainable Optical Glasses

Abstract

Ti3+‐free multicomponent titanophosphate glasses were developed as ecologically sustainable optical glasses. Especially, recent advances in the glasses as molding glass, athermal glass, nonlinear optical glass, and self‐cleaning glass were presented. The Ti3+‐free binary TiO2–P2O5 glasses containing TiO2 up to 74 mol% were prepared by melt quenching and long‐term post‐annealing around the glass transition temperature in the air, and possessed high transparency, high index, high dispersion, and low density. Li2O–ZnO–TiO2–P2O5 glasses have the lowest Tg (=560°C) among titanophosphate glasses, with high index (nd=1.8), and high dispersion (νd=22) being retained, while ZnO–TiO2–P2O5 glasses have the highest refractive index (nd=1.9) among glasses with Tg lower than 600°C. Thus, ZnO–TiO2–P2O5 and Li2O–ZnO–TiO2–P2O5 glasses can be expected as high‐index molding glasses. A very small temperature coefficient of refractive index, dn/dT, or very small temperature coefficient of optical path length, dS/dT, was obtained for K2O–TiO2–P2O5 glasses, meaning that they are considered as high‐index athermal glasses and athermal NLO glasses. Ag2O–TiO2–P2O5 glasses showed photocatalytic activity and photo‐induced hydrophilicity comparable with commercially available TiO2‐coated self‐cleaning glasses.