Patent ID: 8853110

Claim:
A transparent glass-ceramic material containing a spinel solid solution as the main crystalline phase, having a coefficient of thermal expansion of 30-40×10 −7 K −1 over a temperature range of 25-300° C. and a composition that is free of B 2 O 3 , As 2 O 3 and Sb 2 O 3 , with the exception of unavoidable trace thereof, and comprises SnO 2 , TiO 2 and ZrO 2 , and less than 100 ppm of Fe 2 O 3 , wherein the composition, expressed in percentages by weight of oxides, comprises: 0.1-2% of SnO 2 , 2-4% of TiO 2 , and 3-4.5% of ZrO 2 .