Patent ID: 6255240
Filing Date: 2001-07-03
Classification: C03C,Y10S

Abstract:
An inorganic glass that has a refractive index of 1.67-1.72, and that is a member of a borosilicate glass family having compositions that consist essentially of, as calculated in weight percent on an oxide basis:SiO.sub.2 33-37 Li.sub.2 O 5-8 B.sub.2 O.sub.3 7.5-13 Na.sub.2 O >2.5-7.5 Al.sub.2 O.sub.3 0-6 K.sub.2 O 0-2 Nb.sub.2 O.sub.5 8-13 CaO 0-<8 ZrO.sub.2 4-6 SrO 2-4 TiO.sub.2 5-10 As.sub.2 O.sub.3 0-0.8 La.sub.2 O.sub.3 12-19 Sb.sub.2 O.sub.3 0-0.8 SiO.sub.2 + B.sub.2 O.sub.3 44-48 Li.sub.2 O + Na.sub.2 O + K.sub.2 O <14wherein the glass has a surface layer that is under compression and wherein the Na.sub.2 O content is increased and the Li.sub.2 O content is decreased by an ion exchange.