CRYSTALLIZED GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a crystallized glass substrate having a high expansion coefficient and satisfactory workability though alkali metal component of the crystallized glass substrate is low-corrosive. SOLUTION: The crystallized glass substrate for an information recording medium characteristically satisfies the following conditions. 0<; Co<; 150 1.0<; P/PLi<; 1.5 wherein Co: movement quantity [ppb] of the alkali metal component per a substrate for 2.5-inch disk P: a grinding and polishing stock removal [μg/min] per unit time when the glass substrate is polished at 100 g/cm2 by using cerium oxide (having 0.5μm average particle size) as a polishing material to attain 3Åsurface smoothness value PLi: a grinding and polishing stock removal [μg/min] per unit time when a lithium disilicate-based crystallized glass substrate is ground and polished under the same condition as above to attain 3Åsurface smoothness value.