| 摘要 |
PROBLEM TO BE SOLVED: To provide a crystallized glass holding the characteristic of high stiffness (>130 GPa) suitable as a substrate for an information recording medium such as a magnetic recording medium and having excellent characteristics such as high surface smoothness and high surface flatness having a surface roughness Ra suppressed to≤0.5 nm. SOLUTION: This process for preparing the crystallized glass is a method of preparing the crystallized glass obtained by making a glass containing TiO<SB>2</SB>subjected to a phase splitting step and a crystallization step, where the phase splitting step has heat treatment of the glass at a temperature in the range from the glass transition temperature Tg to the glass transition temperature Tg+60°C. The crystallized glass for the information recording disk is the crystallized glass obtained by this preparation process and has≤100 nm average particle diameter of the crystal particle or≥40% transmissivity at 600 nm wave length. The information recording disk is composed of this glass and has a polished surface having 0.1-0.5 nm surface roughness Ra (JIS B0601). COPYRIGHT: (C)2005,JPO&NCIPI
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