Patent ID: 8394515
Filing Date: 2013-03-12
Classification: C03C,G11B

Abstract:
1. A glass substrate for an information recording medium, comprising, as expressed in terms of percent by mass on an oxide basis: 52 to 67% of SiO 3 to 14% of Al 0.2 to 8% of P 1.5 to 20% of MgO, 0 to 10% of CaO, 0 to 10% of ZnO, 0 to 13% of ZrO 0 to 16% of TiO 0 to 1% of CeO 0 to 1% of SnO 0 to 6% of B 4 to 10% of Na 0 to 7% of K wherein a total amount of MgO, CaO, ZnO, ZrO the glass substrate having a Young's modulus of 85 GPa or greater, a specific gravity of 2.60 or less, and a ratio of Young's modulus to specific gravity (Young's modulus/specific gravity) of 33.0 GPa or greater.