| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a crystallized glass and a crystallized glass substrate for an information recording medium including various properties required for application in substrates for next-generation information recording media and having an extremely low specific gravity. <P>SOLUTION: A crystallized glass contains one or more selected from RAl<SB POS="POST">2</SB>O<SB POS="POST">4</SB>and R<SB POS="POST">2</SB>TiO<SB POS="POST">4</SB>(where R is one or more selected from Zn, Mg, and Fe) as a crystalline phase. The crystalline glass contains 40 to 60% SiO<SB POS="POST">2</SB>, 7 to 23% Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, 1 to 15% TiO<SB POS="POST">2</SB>, 1 to 20% MgO, 0 to 10% CaO, 0 to 5% SrO, 0 to 5% BaO, 0 to 15% ZnO, 0 to 8% FeO, 0 to 7% P<SB POS="POST">2</SB>O<SB POS="POST">5</SB>, and 0% or more and less than 8% B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, in terms of mass% based on oxide. The value of (MgO+CaO+SrO+BaO+ZnO+FeO)/(SiO<SB POS="POST">2</SB>+Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>) is 0.25 or less and the value of (ZnO+FeO)/MgO is 0 or more and 0.9 or less. The specific gravity is 2.67 or less. <P>COPYRIGHT: (C)2013,JPO&INPIT |
