GLASS FOR SUBSTRATE FOR DATA STORAGE MEDIUM, GLASS SUBSTRATE FOR DATA STORAGE MEDIUM, AND MAGNETIC DISK

摘要

Disclosed is a glass for a substrate for use in a data storage medium, which can impart high heat resistance to the substrate. Specifically disclosed is a glass for a substrate for use in a data storage medium, which comprises the following components (expressed by mol% in terms of oxide contents): 55-70% of SiO2, 2.5-9% of Al2O3, 0-10% of MgO, 0-7% of CaO, 0.5-10% of SrO, 0-12.5% of BaO, 0-2.5% of TiO2, 0.5-3.7% of ZrO2, 0-2.5% of Li2O, 0-8% of Na2O, 2-8% of K2O and 0.5-5% of La2O3, wherein the total content of Al2O3 and ZrO2 (Al2O3+ZrO2) is 12% or less and the total content of Li2O, Na2O and K2O (R2O) is 12% or less.