Patent ID: 11884584
Assignee: HOYA CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  G | IPC C  G

Claim 0:
1. A glass,
which is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus,
which is an amorphous oxide glass,
wherein an SiO2 content ranges from 56 mol % to 80 mol %;
an Li2O content ranges from 1 mol % to 10 mol %;
a B2O3 content ranges from 0 mol % to 4 mol %;
a Na2O content is 0 mol %;
a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %; and
the oxide glass has a specific gravity of 2.75 g/cm3 or less, a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.