摘要 |
Disclosed are a glass substrate for an information recording medium, having excellent scratch resistance and a light weight and having high fracture toughness, the glass substrate having a fragility index value, measured in water, of 12 mum<SUP>-1/2 </SUP>or less or having a fragility index value, measured in an atmosphere having a dew point of -5° C. or lower, of 7 mum<SUP>-1/2 </SUP>or less, or the glass substrate comprising, by mol %, 40 to 75% of SiO<SUB>2</SUB>, 2 to 45% of B<SUB>2</SUB>O<SUB>3 </SUB>and/or Al<SUB>2</SUB>O<SUB>3 </SUB>and 0 to 40% of R'<SUB>2</SUB>O in which R' is at least one member selected from the group consisting of Li, Na and K), wherein the total content of SiO<SUB>2</SUB>, B<SUB>2</SUB>O<SUB>3</SUB>, Al<SUB>2</SUB>O<SUB>3 </SUB>and R'<SUB>2</SUB>O is at least 90 mol %, and a magnetic information recording medium comprising a magnetic recording layer formed on the glass substrate.
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