| 摘要 |
PROBLEM TO BE SOLVED: To provide a glass composition having a shielding ability comparable to lead glass, high surface hardness, and extremely high transparency in the visible region, in a glass system that contains no lead component and contains a rare earth oxide and fluorine simultaneously. SOLUTION: The glass composition comprises 1-85% of Ln<SB>2</SB>O<SB>3</SB>(wherein Ln represents one or more selected from the group consisting of La, Y, Gd, Tb, Dy, Yb, and Lu) and 0.1-20% of fluorine, by mass in terms of oxide, wherein the glass composition has a lead equivalent to X-rays of 150 kV of 0.03 mmPb/mm or more. Further, a glass composition, which is stable against devitrification, has high surface hardness, and is excellent not only in transparency but also in radiation shielding ability, can be obtained by bringing the total content of SiO<SB>2</SB>and/or B<SB>2</SB>O<SB>3</SB>and/or GeO<SB>2</SB>and/or P<SB>2</SB>O<SB>5</SB>to 10-70%. COPYRIGHT: (C)2008,JPO&INPIT
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