Ti3+-Free Titanoborophosphate Glasses as Molding Glasses with High Refractive Indices
Abstract:Ti3+-free titanoborophosphate TiO2–B2O3–P2O5 (TBP)-based glasses were produced in order to obtain glasses with low Tg (<600°C), high nd (>1.8), and a short postannealing (PA) time (less than a few days). In addition, TBP-based glasses with low Tg (<570°C), high nd (>1.85), and a short PA time were successfully developed with the substitution of Li2O and ZnO for B2O3. Some glasses had very suitable properties for precision glass molding (Tg=553°C, nd=1.851, PA time=4 days for 6Li2O·6ZnO·55TiO2·6B2O3·27P2O5 glass; Tg=563°C, nd=1.880, PA time=2 days for 5Li2O·60TiO2·10B2O3·25P2O5 glass; Tg=566°C, nd=1.885, PA time=3 days for 2.5Li2O·2.5ZnO·60TiO2·10B2O3·25P2O5 glass; and Tg=567°C, nd=1.890, PA time=1 day for 5Li2O·5ZnO·60TiO2·5B2O3·25P2O5 glass). The 70% of TBP-based glasses with nd>1.85 and commercially available molding glasses with nd>1.85 are 40–41 and 44–50, respectively, which means that these new glasses have even higher transparency in the visible region than those currently on the market. Thus, TBP-based glasses are considered to be promising materials as molding glasses with high transparency, low Tg, and high nd.
Document Type: Research Article
Affiliations: 1: Department of Chemistry for Materials, Graduate School of Engineering, Mie University, Mie 514-8507, Japan 2: Koriyama Technical Center, Nidec Copal Corporation, Fukushima 963-8637, Japan
Publication date: June 1, 2009