LITHIUM ALUMINOSILICATE GLASS-CERAMIC, TRANSPARENT, ESSENTIALLY COLORLESS, GENERATING REFINEMENT

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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.