| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical glass having characteristics of a high refractive index and high dispersibility and having excellent devitrification resistance, and to provide a glass material for press molding and an optical element, which comprise the optical glass. SOLUTION: This optical glass contains, by wt.%,≥18% and <30% SiO<SB>2</SB>,≥12% and <23% BaO, 22-37% TiO<SB>2</SB>,≥7% and <16% Nb<SB>2</SB>O<SB>5</SB>, 5-20% Na<SB>2</SB>O, 0-6% K<SB>2</SB>O, 0-5% CaO, 0-5% SrO, 0-4% ZrO<SB>2</SB>, 0-3% Ta<SB>2</SB>O<SB>5</SB>, 0-1% Sb<SB>2</SB>O<SB>5</SB>, and≥0% and <0.5% P<SB>2</SB>O<SB>5</SB>, and is substantially free of PbO, As<SB>2</SB>O<SB>3</SB>, and F. Another optical glass contains SiO<SB>2</SB>, BaO, and TiO<SB>2</SB>, as essential elements, has≥1.80 refractive index (nd), has≤30 Abbe's number (νd), has≤12 pieces/mm<SP>3</SP>numerical density of the crystallized particles that are deposited after being held at a temperature higher by 20°C than the glass transition temperature for 5 hours and then held at 900°C for 5 minutes, and has devitrification resistance. A glass material for press molding and an optical element that comprise one of these optical glass are provided. COPYRIGHT: (C)2007,JPO&INPIT
|
