| 摘要 |
PROBLEM TO BE SOLVED: To provide a glass substrate for an information recording medium having sufficient mechanical strength without crystallizing the glass or chemically strengthening the glass. SOLUTION: The substrate contains 50-70% SiO<SB>2</SB>, 7-20% Al<SB>2</SB>O<SB>3</SB>, 7-17% B<SB>2</SB>O<SB>3</SB>, 0-10% MgO, 0-15% CaO, 0-15% SrO and 0-30% BaO by mass%, and contains substantially no alkali metal oxide and (a fictive temperature - a glass transition temperature) is≥0°C. COPYRIGHT: (C)2007,JPO&INPIT
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