| abstract |
A B S T R A C T A thallium-containing optical glass composition which comprises the following oxides in the indicated proportions in mole%: SiO2 35 - 80, Ti2O 1 - 30, Ti2O + R2O (R being an alkali metal) 1 - 35, ZnO 0 - 35, GeO2 0 - 30, BaO 0 - 25, TiO2 0 - 20, MgO 0 - 20, B2O3 0 - less than 10, ZrO2 0 - 2, Al2O3 0 - 8, SnO 0 - 5, CaO 0 - 10, SrO 0 - 10, PbO 0 - 10, La2O3 0 - 5, Bi2O3 0 - 8, and Ta2O5 0 - 2, and satisfies the following relations: 5 ? ZnO+GeO+BaO+MgO+B2O3 ? 40, 0.1 ? ZrO2+Al2O3+SnO ? 5, and 0 ? CaO+SrO+PbO+La2)3+Ta2O5 ? 10. |