Patent ID: 7465686

Claim:
A glass-ceramic containing a solid solution of β-quartz or of β-spodumene or solid solutions of β-quartz and β-spodumene, as main crystalline phase(s), the composition of which, expressed as percentages by weight of oxides, essentially consists of: SiO 2 60-72 Al 2 O 3 18-23 Li 2 O 2.5-4 MgO 0.5-2 ZnO 1-3 TiO 2 1.5-3.5 ZrO 2 0-2.5 BaO <2 SrO 0-2 CaO 0-2 Na 2 O 0-1.5 K 2 O 0-1.5 P 2 O 5 0-5 B 2 O 3 0-3 F 0.05-1, advantageously 0.05-0.3; and at least one oxide of a multivalent element selected from the group consisting of SnO 2 , V 2 O 5 , CeO 2 , MnO 2 and Fe 2 O 3 , wherein each respective one of said at least one multivalent element oxide comprises at least 0.15% of the glass-ceramic, such that the sum of said multivalent element oxide(s) comprises 0.2-2% of the glass ceramic, wherein SnO 2 , if included, comprises 0.15-0.7% of the glass-ceramic, and barium oxide is present in an amount up to 2%.