| 摘要 |
There is provided a glass-ceramic substrate for an information storage medium usable in an information storage device of the ramp loading system. The glass ceramic substrate has a Young's modulus (GPa)/specific gravity of 37 or over and includes 5.3 to 8 weight percent (expressed on an oxide basis) of Al2O3. The glass ceramic substrate has, as its predominant crystal phases, lithium disilicate (Li2O.2SiO2) and alpha-quartz (alpha-SiO2), has a coefficient of thermal expansion within a range from 65x10-7/° C. to 130x10-7/° C. within a temperature range from -50° C. to +70° C. and has a surface roughness (Ra) (arithmetic mean roughness) of 9 Å or below.
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