Highly refractive, low-density, phototropic glass

摘要

A highly refractive, low-density phototropic glass in which the carriers of phototropy are precipitates containing silver, halogens and copper oxide, and which has a density equal to or less than 3.0 g/cm3, a refractive index equal to or greater than 1.60 and an Abbe number equal to or greater than 40, consisting essentially of, in % by weight on an oxide basis: -SiO2 35-50 -B2O3 13.5-21 - SIGMA SiO2 and B2O3 50-70 -Li2O 0.0-2.5 -Na2O 0.0-4.0 -K2O 0.0-10.0 - SIGMA Alkali metal oxides 4-14 -BaO2 5.0-10.5 -TiO2 3.5-6.5 -ZrO2 4.5-9.5 -Nb2O3 5.0-11.5, - the total of the foregoing oxides being 100% by weight, and in addition to the basic glass composition, carriers of phototropy consisting essentially of, in % by weight: -Ag2O 0.05-0.25 -Br 0.07-0.25 -Cl 0.06-0.35 - SIGMA Br and Cl