Patent ID: 8722215
Filing Date: 2014-05-13
Classification: C03C,G11B,Y10T

Abstract:
1. A glass substrate for an information recording medium made of aluminosilicate glass containing 60% to 75% by mass of SiO 2 , 5% to 18% by mass of Al 2 O 3 , 3% to 10% by mass of Li 2 O, 3% to 15% by mass of Na 2 O, and 0.5% to 8% by mass of ZrO 2 with respect to whole glass components, and containing neither As (arsenic) element nor Sb (antimony) element, comprising: at least one polyvalent element selected from the group consisting of V (vanadium), Mn (manganese), Ni (nickel), Nb (niobium), Mo (molybdenum), Sn (tin), Ce (cerium), Ta (tantalum), and Bi (bismuth); wherein a molar ratio of a whole amount of the comprised polyvalent element to the ZrO wherein the glass substrate in molten form is press-molded to form the recording medium; and wherein a total content of the comprised polyvalent element is 1% by mass or less with respect to the whole glass components, where each of the polyvalent elements is converted in terms of the following oxides: V