Importance

Loading Importance Indicators...

Abstract

A glass substrate for a magnetic disk of the present invention is one in which a laser beam is irradiated on a magnetic recording surface side thereby forming a large number of protrusions thereon to form texture thereon, each of the protrusions having a convex shape, an optical absorption coefficient of a glass with respect to a wavelength of a laser beam at 266 nm being within a range of 20 to 2000 mm.sup.-1, the glass having a composition by weight of: silicon oxide (SiO.sub.2): 58 to 66%, aluminum oxide (Al.sub.2 O.sub.3): 13 to 19%, lithium oxide (Li.sub.2 O): 3 to 4.5%, sodium oxide (Na.sub.2 O): 6 to 13%, potassium oxide (K.sub.2 O); 0 to 5%, R.sub.2 O: 9 to 18% (provided R.sub.2 O=Li.sub.2 O+NaO+K.sub.2 O), magnesium oxide (MgO): 0 to 3.5%, calcium oxide (CaO): 1 to 7%; strontium oxide (SrO): 0 to 2%; barium oxide (BaO): 0 to 2%, RO: 2 to 10% (provided RO=MgO+CaO+SrO+BaO), and iron oxide (Fe.sub.2 O.sub.3): 0.05 to 2%, titanium oxide (TiO.sub.2): 0 to 2%, cerium oxide(CeO.sub.2): 0 to 2%, and manganese oxide(MnO): 0 to 1%, (provided that Fe.sub.2 O.sub.3 +TiO.sub.2 +CeO.sub.2 +MnO=0.05 to 3%).

Loading the Abstract Image...

First Claim