Glass-ceramic substrate for an information storage medium
First Claim
1. A glass-ceramic substrate for an information storage medium comprising, as a predominant crystal phase, lithium disilicate (Li2O·
- 2SiO2) having a crystal grain diameter (average) of 0.05 μ
m or below.
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Abstract
A glass-ceramic substrate for an information storage medium includes, as a predominant crystal phase, lithium disilicate (Li2O·2SiO2) or a combination of lithium disilicate and at least one crystal phase selected from the group consisting of α-quartz (α-SiO2), α-quartz solid solution (α-SiO2 solid solution), α-cristobalite (α-SiO2) and α-cristobalite solid solution (α-SiO2 solid solution). This substrate has Young'"'"'s modulus (GPa)/specific gravity of 37 or over, surface roughness Ra (arithmetic mean roughness) of 5.0 Å or below, a coefficient of thermal expansion within a temperature range from −50° C. to +70° C. which ranges from +65×10−7/° C. to +130×10−7/° C. and bending strength of 400 MPa or over.
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Citations
15 Claims
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1. A glass-ceramic substrate for an information storage medium comprising, as a predominant crystal phase, lithium disilicate (Li2O·
- 2SiO2) having a crystal grain diameter (average) of 0.05 μ
m or below. - View Dependent Claims (2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- 2SiO2) having a crystal grain diameter (average) of 0.05 μ
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3. A glass-ceramic substrate consisting of a crystal phase or phases and an amorphous phase and having a crystal grain diameter (average) of 0.05 μ
- m or below and comprising SiO2 in the amount of 70-77% and Li2O in the amount of 8-12% wherein Young'"'"'s modulus (Gpa)/specific gravity is 37 or over.
Specification