abstract |
The present invention relates to an article comprising at least one of a glass or glass-ceramic comprising Al 2 O 3 and at least one of REO or Y 2 O 3 , wherein at least 60 percent by weight of the glass or glass-ceramic comprise the Al 2 O 3 and the at least one of REO or Y 2 O 3 , and wherein the glass or glass-ceramic contains not more than 40 percent by weight collectively SiO 2 , B 2 O 3 , and P 2 O 5 , based on the total weight of the glass or glass-ceramic. |