Transparent, essentially colorless, tin-fined las glass-ceramics with improved microstructure and thermal expansion properties

摘要

The object of the present application is β-quartz glass-ceramics (having very interesting optical, thermal expansion and feasibility properties), the articles including said glass-ceramics; the precursor glasses of said glass-ceramics, as well as the methods for elaborating said glass-ceramics and said articles. Said glass-ceramics having a composition, free, except for inevitable trace amounts, of arsenic oxide, antimony oxide and rare earth oxide, which contains, expressed in percentages by weight of oxides: 64 to 70% of SiO₂, 18 to 24% of Al₂O₃, 4 to 5% of Li₂O, 0 to 0.6% of SnO₂, >1.9 to 4% of TiO₂, 1 to 2.5% of ZrO₂, 0 to 1.5% of MgO, 0 to 3% of ZnO, >0.3 to 1 of CaO, 0 to 3% of BaO, 0 to 3% of SrO, with BaO+SrO≤3%, 0 to 1.5% of Na₂O, 0 to 2% of K₂O, with 0.2<(MgO+Na₂O+K₂O)/Li₂O≤1, 0 to 3% of P₂O₅, less than 250 ppm of Fe₂O₃; and their crystallites, present in said β-quartz solid solution, have an average size of less than 40 nm, advantageously less than 35 nm, very advantageously less than 30 nm.