| 摘要 |
A glass-ceramic substrate for a magnetic information storage medium includes, as predominant crystal phases, lithium disilicate (Li2O.2SiO2) and at least one selected from a group consisting of alpha-quartz (alpha-SiO2), alpha-quartz solid solution (alpha-SiO2 solid solution), alpha-cristobalite (alpha-SiO2) and alpha-cristobalite solid solution (alpha-SiO2 solid solution) and has a coefficient of thermal expansion of +65 to +130x10-7/° C. at a temperature within a range from -50° C. to +70° C. and surface roughness (Ra) after polishing of 3 Å-9 Å.
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