| 摘要 |
PROBLEM TO BE SOLVED: To provide optical glass whose transition temperature is low, in combination with desired optical characteristics (n<SB>d</SB>/ν<SB>d</SB>), without using PbO and without using As<SB>2</SB>O<SB>3</SB>as much as possible. SOLUTION: The composition of lead-free and preferably arsenic-free optical dense barium crown glass is exhibited by volume and oxide basis such as 43-56% P<SB>2</SB>O<SB>5</SB>, 21-36% ZnO, 0-6% Al<SB>2</SB>O<SB>3</SB>, 0.5-16% Na<SB>2</SB>O, 0-8% K<SB>2</SB>O,ΣM<SB>2</SB>O(alkali metal oxide)≤16%, 0-5% MgO, 0-5% CaO, 3-14% BaO, 0-8% B<SB>2</SB>O<SB>3</SB>and 0-7% La<SB>2</SB>O<SB>3</SB>. Its refractive index (n<SB>d</SB>) range is denoted as 1.55≤n<SB>d</SB>≤1.60, its Abbe number (ν<SB>d</SB>) range is denoted as 54≤ν<SB>d</SB>≤63 and its transition temperature (Tg) is 500°C or below. The glass can be suitably used as an optical element in application fields such as a picture, projection, a long distance communication, an optical communication technique and a laser technique. COPYRIGHT: (C)2004,JPO
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