GLASS SUBSTRATE FOR INFORMATION RECORDING MEDIUM

摘要

Disclosed is a glass substrate for an information recording medium, which is capable of improving long-term reliability. Specifically disclosed is a glass substrate for an information recording medium, which contains, in weight%, the following glass components: 52-67 of SiO2, 8-20 of Al2O3 and 0-6 of B2O3 (including 0, and hereinafter the same shall apply), with the total of these three oxides FMO being 70-85; 0.5-4 of Li2O, 1-8 of Na2O, and 0-5 of K2O, with the total of these three oxides R2O being 5-15; 2-9 of MgO, 0.1-5 of CaO, 0-3 of BaO, 0-3 of SrO and 0-5 of ZnO, with the total of these five oxides being 5-15; 0-4 of Y2O3; 0-4 of La2O3; 0-4 of Gd2O3; 0-4 of CeO2; 1-7 of TiO2; 0-2 of HfO2; 0-5 of ZrO2; 0.2-5 of Nb2O5; and 0-5 of Ta2O5. In addition, the glass substrate for an information recording medium is configured such that Li2O/R2O is 0.05-0.35, Li2O/FMO is 0.005-0.035, Li2O/(MgO + ZnO) is less than 2, and Nb2O5/SiO2 is 0.01-0.075.