Patent ID: 7179526

Claim:
A composite material comprising discrete crystalline regions within an amorphous matrix, wherein the crystalline regions and the amorphous matrix each independently comprise at least 35 percent by weight Al 2 O 3 , based on the total weight of the crystalline regions and the amorphous matrix, respectively, and a metal oxide other than Al 2 O 3 , wherein the crystalline regions and the amorphous matrix each contain not more than 10 percent by weight collectively As 2 O 3 , B 2 O 3 , GeO 2 , P 2 O 5 , SiO 2 , TeO 2 , and V 2 O 5 , based on the total weight of the crystalline regions and the amorphous matrix, respectively, and wherein the composite material has x, y, and z dimensions each perpendicular to each other, and wherein each of the x, y, and z dimensions is at least 150 micrometers.