| 摘要 |
PROBLEM TO BE SOLVED: To obtain a glass ceramic substrate for a magnetic information record medium ensuring very small extents of thermal deformation and warpage even at the time of high temp. film formation for an oxide-base perpendicular magnetic record medium or the like. SOLUTION: The principal crystal phase of the glass ceramic substrate is one or more selected fromβ-quartz (β-SiO2 ),β-quartz solid solns. (β-SiO2 solid solns.),β-spodumene (β-Li2 O.Al2 O3 .SiO2 ),β-spodumene solid solns. (β-Li2 O.Al2 O3 .SiO2 solid solns.),β-eucryptite (β-Li2 O.Al2 O3 .2SiO2 in which part of the Li2 O can be substd. by MgO and/or ZnO) andβ-eucryptite solid solns. (β-Li2 O.Al2 O3 .2SiO2 solid solns. in which part of the Li2 O can be substd. by MgO and/or ZnO) or the principal crystal phase is gahnite (ZnAl2 O3 ) and/or a gahnite solid soln. (ZnAl2 O3 , solid soln.).
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