| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a glass substrate reducing the incidence of information errors in a recording medium of a thermally assisted recording system, and suppressing the breakage of a magnetic head. <P>SOLUTION: The glass substrate includes a composition of 58-68% of SiO<SB POS="POST">2</SB>, 0-5% of Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, 0-2% of B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>(provided that SiO<SB POS="POST">2</SB>+Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>+B<SB POS="POST">2</SB>O<SB POS="POST">3</SB>=58-68%), 1-6% of Na<SB POS="POST">2</SB>O, 7-15% of K<SB POS="POST">2</SB>O (provided that Na<SB POS="POST">2</SB>O+K<SB POS="POST">2</SB>O=8-21%), 2-7% of MgO, 7-15% of CaO, 0-5% of BaO, 0-5% of SrO, 0-5% of ZnO (provided that MgO+CaO+BaO+SrO+ZnO=9-22%), and 6-12% of ZrO<SB POS="POST">2</SB>, expressed by mass% in terms of oxides, and does not contain Li<SB POS="POST">2</SB>O. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
