| 摘要 |
PURPOSE:To obtain a crystallized glass for a substrate which has proper hardness and a minute and homogeneous structure and is small in the change of thermal expansion coefficient by heat-treatment temp., by heat-treating SiO2-Li2 O-P2O5-MgO base glass in which P2O5 of comparatively small amount and MgO of specified amount are essentially incorporated at the specified temp. CONSTITUTION:Glass contg. by weight 60-87% SiO2, 5-15% Li2O, 0-10% Na2O, 0-10% K2O, 0.5-7.5% MgO, 0-9.5% CaO, 0-15% SrO, 0-13% BaO, 0-13% PbO, 0-13% ZnO, 0-10% B2O3, 0-10% Al2O3, 0.5-8% P2O5, 0-5% TiO2, 0-3% ZrO2, 0-3% SnO2, 0-2% (As2O3+Sb2O3) and 0-5% fluoride of one or two and more kinds of metallic elements of the above-mentioned each metallic oxide as total amounts of F is heat-treated at crystallization temp. not more than 850 deg.C.
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