Glasses of the Na.sub.2 0--T.sub.2 0.sub.5 --SiO.sub.2 and the Na.sub.2 0--L.sub.2 0--a.sub.2 0.sub.5 --SiO.sub.2 system
US3984251A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 5, 1971 |
| Grant date | Oct 5, 1976 |
| Priority date | — |
| Expiry date | Aug 5, 1991 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03C10/0018
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Thermally crystallizable glasses of the Na.sub.2 O--Ta.sub.2 O.sub.5 --SiO.sub.2 and the Na.sub.2 O--Li.sub.2 O--Ta.sub.2 O.sub.5 --SiO.sub.2 systems, and glass-ceramics made therefrom which are highly transparent, have high indices of refraction, and excellent strength properties. The glasses of the first system consist essentially of about 37-55 mole percent SiO.sub.2, 23-35 mole percent Ta.sub.2 O.sub.5, and 20-33 mole percent Na.sub.2 O, preferably where the molar ratio of Na.sub.2 O to Ta.sub.2 O.sub.5 is about 1, and for the second system the glasses consist essentially of about 27-45 mole percent SiO.sub.2, 32-45 mole percent Ta.sub.2 O.sub.5, and 20-35 mole percent Li.sub.2 O plus Na.sub.2 O, preferably wherein the molar ratio of Li.sub.2 O to Na.sub.2 O is within the range of from 0.7:1 to 1.2:1, and the molar ratio of Na.sub.2 O + Li.sub.2 O to Ta.sub.2 O.sub.5 is within the range of 0.5:1 to about 1:1. Glasses and glass-ceramics of the latter system also have good dielectric properties and low loss tangents. By varying the heat treatment schedule for crystallization of a glass to a glass-ceramic, a specific high index of refraction coming within a prescribed range may be…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.