| 摘要 |
PROBLEM TO BE SOLVED: To provide optical glass for mold pressing which has an index of refraction (nd) of 1.60 to 1.67, an Abbe's number (νd) of≥55, is pressed at a low temperature, is hard to undergo devitrification in the process of a pressing process, and has high weather resistance. SOLUTION: The optical glass does not contain TiO<SB>2</SB>, Nb<SB>2</SB>O<SB>3</SB>nor PbO, and has a composition of, by mass, 11.5 to 45% SiO<SB>2</SB>, 0.5 to 15% Al<SB>2</SB>O<SB>3</SB>, 10.5 to 45% B<SB>2</SB>O<SB>3</SB>, 0 to 10% MgO, 0 to 13% CaO, 0 to 12% BaO, 0 to 9.5% SrO, 0 to 9% ZnO, 0 to 1% ZrO<SB>2</SB>, 3.5 to 12% Li<SB>2</SB>O, 0 to 10% Na<SB>2</SB>O, 0 to 10% K<SB>2</SB>O, 0 to 1% Sb<SB>2</SB>O<SB>3</SB>, 5 to 30% La<SB>2</SB>O<SB>3</SB>, 0 to 5.5% Gd<SB>2</SB>O<SB>3</SB>, 0 to 10% Ta<SB>2</SB>O<SB>5</SB>, 0 to 5% Bi<SB>2</SB>O<SB>3</SB>, 0 to 25% RO (R is one or more kinds selected metals from Mg, Ca, Ba and Sr), RO/La<SB>2</SB>O<SB>3</SB><1.7, and 0.1≤Al<SB>2</SB>O<SB>3</SB>/La<SB>2</SB>O<SB>3</SB>≤0.6. COPYRIGHT: (C)2003,JPO
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