Patent ID: 8318619

Claim:
A transparent, essentially colorless glass-ceramic material, comprising a β-quartz solid solution as a predominant crystalline phase, having a composition, expressed in terms of weight percentages on a basis of oxides, consisting essentially of: SiO 2 >65-71 Al 2 O 3 19-23 Li 2 O 3-4 B 2 O 3 ≧0-1 TiO 2 0.3-<1.6 SnO 2 0.25-1.2 CeO 2 0-0.4 WO 3 + MoO 3 0-<1 CeO 2 + WO 3 + MoO 3 0-<1 Nb 2 O 5 0-0.6 ZrO 2 2.2-3.8 ZrO 2 + TiO 2 + SnO 2 >3.0-<4.8 MgO 0-2 ZnO 1-4 SrO 0-2 BaO 0-1.8 P 2 O 5 0-3 K 2 O + Na 2 O 0-1.5 Gd 2 O 3 + La 2 O 3 + Ta 2 O 5 + Y 2 O 3 0-4 Nd 2 O 3 + Er 2 O 3 0-0.08 Fe 2 O 3 <0.03; and free of arsenic oxide and antimony oxide, with the exception of unavoidable traces thereof and further comprising an amount of B 2 O 3 effective to dissolve ZrO 2 .