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|1. (WO2017061501) GLASS FOR DATA STORAGE MEDIUM SUBSTRATE, GLASS SUBSTRATE FOR DATA STORAGE MEDIUM, AND MAGNETIC DISK|
|Applicants:||ASAHI GLASS COMPANY, LIMITED
|Title:||GLASS FOR DATA STORAGE MEDIUM SUBSTRATE, GLASS SUBSTRATE FOR DATA STORAGE MEDIUM, AND MAGNETIC DISK|
The present invention pertains to a glass for a data storage medium substrate which contains a specific amount of each of SiO2, Al2O3, MgO, CaO, SrO, BaO, Li2O, Na2O, and K2O, in molar percentage based on the oxides, and does not substantially contain B2O3 or ZrO2, wherein the sum of the Li2O, Na2O, and K2O contents (R2O), the molar ratio of the SiO2 content to the Al2O3 content (SiO2/Al2O3), and the molar ratio of the sum of the SiO2 and Al2O3 contents (SiO2+Al2O3) to R2O [(SiO2+Al2O3)/R2O] fall within their specific ranges, formula (1): 90 < [SiO2] + 2 × [Al2O3] + 0.8 × [RO] - 0.5 × [R2O] [in formula (1), RO represents the sum of the MgO, CaO, SrO, and BaO contents] is satisfied, and the glass transition point Tg, the alkali resistance, and the acid resistance fall within their specific ranges.