Lead-free optical borosilicate glass, for optical equipment and optical data applications, contains barium, zinc, titanium, niobium and rare earth oxides and has a high refractive index and a low Abbe number

摘要

Lead-free optical glasses, having specified silicon, boron, barium, zinc, titanium, niobium and rare earth oxide contents, a high refractive index and a low Abbe number, are new. Novel lead-free optical glasses have the composition (by wt., on oxide basis) 10-25% SiO2, greater than 10-25% B2O3, 2.5-10% Na2O, 0-3% K2O, 0.5-5% CaO, 15-30% BaO, 5-15% ZnO, 6-15% TiO2, 0.5-8% ZrO2, 0.1-2% Y2O3, 0.5-8% La2O3, 6-12% Nb2O5, 0-1% Ta2O5, 0-1% Gd2O3 and optionally usual amounts of refiners, the sum of La2O3 + Nb2O5 being /-17%.