| 摘要 |
PURPOSE:To obtain inexpensively glass having high viscosity during melting, low crystal growth ratio at <= the liquid phase temperature, capable of being directly shaped by press molding from a continuous melting furnace, using Li2O and ZrO2 instead of Nb2O3 and Ta2O3 because of the reduction in the melting temperature of glass composition suppressing the content of B2O3. CONSTITUTION:Optical glass having a composition wherein 21.0<=SiO2<=35.0, 0<=B2O3<=10.0, 0<=Al2O3<=4.0, 0.5-Li2O<=4.0, 19.0<=BaO<=45.0, 0<=SrO<=15.0, 0<= CaO<=20.0, 0<=MgO<=5.0, 1.5<=ZnO<=20.0, 8.0<=La2O3<=23.0, 2.0<=ZrO2<=8.0, 0<= TiO2<=10.0, 0<=Nb2O3+Ta2O3<=4.5, 0<=WO<=5.0, 0<=PbO<=5.0 (with the proviso that 33.0<=BaO+SrO+CaO+MgO+ZnO<=55.0) by wt%. Li2O Stabilizes glass and improves the solubility of SiO2. ZrO2 improves refractive index, stability, viscosity, chemical durability and hardness.
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