Patent ID: 8394515

Claim:
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 2 , 3 to 14% of Al 2 O 3 , 0.2 to 8% of P 2 O 5 , 1.5 to 20% of MgO, 0 to 10% of CaO, 0 to 10% of ZnO, 0 to 13% of ZrO 2 , 0 to 16% of TiO 2 , 0 to 1% of CeO 2 , 0 to 1% of SnO 2 , 0 to 6% of B 2 O 3 , 4 to 10% of Na 2 O, and 0 to 7% of K 2 O, wherein a total amount of MgO, CaO, ZnO, ZrO 2 and TiO 2 in the glass substrate is 5 to 20% by mass on the oxide basis, and the total amount of CeO 2 and/or SnO 2 is 0.05 to 1% by mass on the oxide basis, and the total amount B 2 O 3 , Na 2 O, and/or K 2 O is 4 to 11%) by mass on the oxide basis, 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.