TRANSPARENT, COLORLESS, TIN-FINED LAS GLASS-CERAMICS WITH IMPROVED MICROSTRUCTURE AND OPTICAL PROPERTIES

摘要

Transparent, essentially colorless and non-diffusing β-quartz glass-ceramics and glass compositions for forming the same have a composition, free of arsenic oxide, antimony oxide and rare earth oxides except for inevitable trace amounts, which contains, expressed as percentages by weight of oxides 62-72% of SiO₂, 20-23% of Al₂O₃, 2.8-5% of Li₂O, 0.1-0.6% of SnO₂, 1.9-4% of TiO₂, 1.6-3% of ZrO₂, less than 0.4% of MgO, 2.5-6% of ZnO and/or BaO and/or SrO, less than 250 ppm of Fe₂O₃; and their crystallites present in the β-quartz solid solution have an average size of less than 35 nm. The glass-ceramics exhibit low thermal expansion and are easily obtained at an industrial scale.