| 摘要 |
PURPOSE:To obtain the titled glass wherein specific gravity, refractive index and Abbe number are respectively regulated to specified ranges and it is suitable for spectacles by incorporating the composition of a specified range. CONSTITUTION:The titled glass is obtained which has the composition of by wt% 5-36SiO2, 6-35B2O>=3 however 23-42 (SiO2+B2O3), 0-8 MgO, 0-27 CaO, 0-4 BaO, 0-11 ZnO however 10-32 (MgO+CaO+BaO+ZnO), 16-32 TiO2, 17-27 La2O3, 0-2 Y2O3, 0-2 Yb2O3, 0-10 Al2O3, 0-4 Li2O, 0-4 Na2O, 0-4 K2O however 0-4 (Li2O+Na2O+K2O), 0-7 ZrO2, 0-13 Nb2O5 and 0-0.2 Nd2O3, and is regulated to 1.80-1.85 refractive index (nd), 29-32 Abbe number (Vd) and 3.0-3.7 specific gravity. Glass having 1.80-1.84 refractive index (nd), 31-32 (excluding 32) Abbe number (Vd) and 3.0-3.7 specific gravity is obtained from the composition of by wt% 16-25 TiO2, 4-13 Nb2O5, 9-25 CaO and 18-27 La2O3 among these compositions for glass and therefore is especially preferable as glass for spectacles.
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