| 摘要 |
PROBLEM TO BE SOLVED: To provide a BaO-free and PbO-free X-ray opaque glass which is suitable as dental glass or optical glass and has zirconium having a relatively low refractive index n<SB>d</SB>. SOLUTION: The BaO-free and PbO-free X-ray opaque glass is the system SiO<SB>2</SB>-B<SB>2</SB>O<SB>3</SB>-Al<SB>2</SB>O<SB>3</SB>-R<SB>2</SB>O-RO-La<SB>2</SB>O<SB>3</SB>-ZrO<SB>2</SB>, mass% in terms of oxide, wherein the glass comprises 48-56% of SiO<SB>2</SB>, 3-8% of B<SB>2</SB>O<SB>3</SB>, 0.5-4% of Al<SB>2</SB>O<SB>3</SB>, 0-5% of Li<SB>2</SB>O, 1-4% of Na<SB>2</SB>O, 2-7% of K<SB>2</SB>O, 10-16% of Cs<SB>2</SB>O, 5-9% of CaO, 0-5% of MgO, 0.5-13% of ZrO<SB>2</SB>, 5-12% of La<SB>2</SB>O<SB>3</SB>, 0-4% of SnO<SB>2</SB>, 16-21% ofΣalkali metal oxides, and the amount of Cs<SB>2</SB>O+La<SB>2</SB>O<SB>3</SB>+SnO<SB>2</SB>≥19%, wherein the glass has a refractive index n<SB>d</SB>of 1.54-1.58 and an aluminium equivalent thickness of at least 500%. COPYRIGHT: (C)2011,JPO&INPIT
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