Patent ID: 8304081

Claim:
A process for making a SiO 2 —RE x O y —Al 2 O 3 glass comprising preparing a glass according to a conventional process wherein the conventional process comprises a step of heat treating a mixture of SiO 2 , RE x O y , and Al 2 O 3 at a temperature greater than the spinodal temperature for 0.1 to 10 hours, wherein RE x O y is a rare earth oxide and RE is a rare earth element chosen from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof, wherein said glass comprises, in terms of mol percent on an oxide basis, about 60 to about 98.9 mol % SiO 2 , about 10 to about 35 mol % Re x O y , and about 0.1 to about 30 mol % Al 2 O 3 .