Glass material

Abstract

A glass including SiO 2 , Na 2 O, MgO, Al 2 O 3 , and cobalt oxide, wherein the cobalt oxide is 4.5-85 wt % as an oxide of CoO or 4.9-91 wt % as an oxide of Co 3 O 4 .

What is claimed is:  
     
         1 . A glass thin film comprising at least one of transition metal oxides and rare earth element oxides in an amount of 37.4% by weight, which is formed on an optical information recording medium by a sputtering method using a sintered body including said at least one of transition metal oxides and rare earth element oxides as a sputtering target.  
     
     
         2 . A glass thin film according to  claim 1 , wherein said glass thin film is between a substrate of said optical information recording medium and a recording film, or on a recording film formed on a substrate.  
     
     
         3 . A glass thin film according to  claim 1 , wherein said glass thin film is on a substrate of said optical information recording medium whereon information is written.  
     
     
         4 . A glass thin film according to  claim 1 , wherein transition metals and rare earth elements, for forming said transition metal oxides and said rare earth element oxides, are selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nd, Ce, Pr, Sm, Eu, Tb, Ho, Er and Tm.  
     
     
         5 . A glass thin film according to  claim 4 , wherein said glass thin film further comprises silicon oxide, alkali oxide, and boron oxide.  
     
     
         6 . A glass thin film according to  claim 1 , wherein said glass thin film comprises cobalt oxide as said at least one of transition metal oxides and rare earth element oxides, and the residual of said glass thin film is made of silicon oxide, alkali oxide, and boron oxide.  
     
     
         7 . A glass thin film according to  claim 1 , wherein light intensity distribution therein is variable.  
     
     
         8 . A glass thin film for an optical information recording medium, comprising SiO 2  and cobalt oxide, wherein said cobalt oxide is included in an amount of 4.5-85% by weight as an oxide of CoO or 4.9-91% by weight as an oxide of Co 3 O 4 , and wherein the glass thin film has an intensity distribution of light transmitted therethrough that varies non-linearly in contrast to the intensity distribution of light exposed thereon.  
     
     
         9 . A glass thin film for optical information recording medium according to  claim 8 , wherein said cobalt oxide is included in an amount of 4.5 to 85% by weight as an oxide of CoO.  
     
     
         10 . A glass thin film for optical information recording medium according to  claim 8 , wherein said cobalt oxide is included in an amount of 4.5 to 85% by weight as an oxide of CoO or 28.6 to 91% by weight as an oxide of Co 3 O 4 .  
     
     
         11 . A glass thin film for an optical information recording medium comprising SiO 2  and cobalt oxide, wherein said cobalt oxide is included in an amount of 20 to 90% by weight calculated as an oxide of CoO.  
     
     
         12 . A sintered body for sputtering of an optical information recording medium, which contains Co oxide in an amount of at least 37.4% by weight.