| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass for moulding press moldings that is press-moldable at a low temperature and has high weatherability, of which the refractive index(nd) is 1.60-less than 1.65 and the Abbe's number(νd) is 55 or more. SOLUTION: The optical glass is characterized by comprising as ingredients 11.5-45% of SiO<SB>2</SB>, 0.5-11% of Al<SB>2</SB>O<SB>3</SB>, 10.5-45% of B<SB>2</SB>O<SB>3</SB>, 0-10% of MgO, 0-13% of CaO, 0-12% of BaO, 0-9.5% of SrO, 0-9% of ZnO, 0-5% of ZrO<SB>2</SB>, 3.5-12% of Li<SB>2</SB>O, 0-10% of Na<SB>2</SB>O, 0-10% of K<SB>2</SB>O, 0-1% of Sb<SB>2</SB>O<SB>3</SB>, 5-18.5% of La<SB>2</SB>O<SB>3</SB>, 5.5-15% of Gd<SB>2</SB>O<SB>3</SB>, 0-10% of Ta<SB>2</SB>O<SB>5</SB>, 0-5% of Bi<SB>2</SB>O<SB>3</SB>based on % by mass, with RO/(La<SB>2</SB>O<SB>3</SB>+Gd<SB>2</SB>O<SB>3</SB>) being 0.53 (wherein R is one or more of Mg, Ca, Ba and Sr) and satisfying the following formula: 0.1≤Al<SB>2</SB>O<SB>3</SB>/La<SB>2</SB>O<SB>3</SB>≤0.6. COPYRIGHT: (C)2004,JPO
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