Patent ID: 10487003

Abstract:
Borosilicate glasses are disclosed having (in weight %) 66-76% SiO2, 0-8% Al2O3, 10-18% B2O3, 0-4% Li2O, 0-12% Na2O, 0-12% K2O, 1-1.5% Ag, 1.5-2.5% Cl− and 0.01-0.06% of a summed amount of CuO and NiO, wherein the glass composition is bleachable upon exposure to ultraviolet irradiation from a stable state color or shade to a lighter color or shade. Such reverse photochromic borosilicate glass compositions may be thermally darkenable. The borosilicate glasses may be strengthened via ion-exchange strengthening treatment. The borosilicate glasses may retain their reverse photochromic and thermally darkenable properties even after ion-exchange strengthening treatment.