초록 ▼

To provide glass for a data storage medium substrate, whereby high heat resistance can be obtained. Glass for a data storage medium substrate, which comprises, as represented by mol percentage based on the following oxides, from 55 to 70% of SiO2, from 2.5 to 9% of Al2O3, from 0 to 10% of MgO, from

To provide glass for a data storage medium substrate, whereby high heat resistance can be obtained. Glass for a data storage medium substrate, which comprises, as represented by mol percentage based on the following oxides, from 55 to 70% of SiO2, from 2.5 to 9% of Al2O3, from 0 to 10% of MgO, from 0 to 7% of CaO, from 0.5 to 10% of SrO, from 0 to 12.5% of BaO, from 0 to 2.5% of TiO2, from 0.5 to 3.7% of ZrO2, from 0 to 2.5% of Li2O, from 0 to 8% of Na2O, from 2 to 8% of K2O and from 0.5 to 5% of La2O3, provided that the total content of Al2O3and ZrO2(Al2O3+ZrO2) is at most 12%, and the total content of Li2O, Na2O and K2O (R2O) is at most 12%.

대표청구항 ▼

What is claimed is: 1. Glass for a data storage medium substrate, which comprises, as represented by mol percentage based on the following oxides, from 55 to 70% of SiO2, from 2.5 to 9% of Al2O3, from 0 to 10% of MgO, from 0 to 7% of CaO, from 1 to 10% of SrO, from 0.5 to 12.5% of BaO, from 0 to 2.

What is claimed is: 1. Glass for a data storage medium substrate, which comprises, as represented by mol percentage based on the following oxides, from 55 to 70% of SiO2, from 2.5 to 9% of Al2O3, from 0 to 10% of MgO, from 0 to 7% of CaO, from 1 to 10% of SrO, from 0.5 to 12.5% of BaO, from 0 to 2.5% of TiO2 from 0.5 to 3.7% of ZrO2, from 0 to 2.5% of Li2O, from 0 to 5% of Na2O, from 2 to 8% of K2O and from 0.5 to 5% of La2 O3, provided that the total content of Al2O3 and ZrO2 (Al2O3+ZrO2) is at most 12%, and the total content of Li2O, Na2O and K2O (R2O) is at most 10%, wherein a difference obtained by subtracting the Li2O content from the total content of SrO and BaO is at least 2 mol %. 2. The glass for a data storage medium substrate according to claim 1, wherein the mol ratio of the total content of Li2O and Na2O to the K2O content ((Li2O+Na2O)/K2O) is at most 1.4. 3. The glass for a data storage medium substrate according to claim 1, wherein the total content of MgO, CaO, SrO and BaO is at least 10 mol %. 4. The glass for a data storage medium substrate according to claim 1, wherein a value obtained by dividing a product of the Al2O3 content multiplied by the total content of ZrO2, K2O and La2O3, by the total content of MgO, CaO, SrO and BaO (Al2O3×(ZrO2+K2O+La2O3)÷(MgO+CaO+SrO+BaO)) is at most 4.0 mol %. 5. The glass for a data storage medium substrate according to claim 1, wherein the total content of Al2O3 and ZrO2 is at most 9 mol %, and the total content of Al2O3, ZrO2, K2O and La2O3 is at most the total content of MgO, CaO, SrO and BaO. 6. The glass for a data storage medium substrate according to claim 1, wherein the total content of Al2O3 and ZrO2 is more than 9 mol %, and the total content of ZrO2 and K2O is less than 9 mol %. 7. The glass for a data storage medium substrate according to claim 1, wherein the total content of MgO, CaO and TiO2 is at most 16 mol %. 8. The glass for a data storage medium substrate according to claim 1, wherein the content of Al2O3 is, as represented by mass percentage, less than 11%. 9. A glass substrate for a data storage medium, which is made of the glass for a data storage medium substrate as defined in claim 1. 10. A magnetic disk having a magnetic recording layer formed on the glass substrate for a data storage medium as defined in claim 9. 11. The glass for a data storage medium substrate according to claim 1, which has a Young's modulus of 75 to 90 GPa.