Glass Substrate For Information Recording Medium

摘要

The present invention relates to the glass substrate for an information recording medium comprising the following glass components: SiO2: 52 to 67; Al2O3: 8 to 20; B2O3: 0 to 6, with these three oxides FMO: 70 to 85; Li2O: 0.5 to 4; Na2O: 1 to 8; K2O: 0 to 5; and with these three oxides R2O: 5 to 15; MgO: 2 to 9; CaO: 0.1 to 5; BaO: 0 to 3; SrO: 0 to 3; ZnO: 0 to 5; and with these five oxides: 5 to 15; Y2O3: 0 to 4; La2O3: 0 to 4; Gd2O3: 0 to 4; CeO2: 0 to 4; TiO2: 1 to 7; HfO2: 0 to 2; ZrO2: 0 to 5; Nb2O5: 0.2 to 5; and Ta2O5: 0 to 5, and satisfies Li2O/R2O: 0.05 to 0.35; Li2O/FMO: 0.005 to 0.035; Li2O/(MgO+ZnO): less than 2 and Nb2O5/SiO2: 0.01 to 0.075.