Minolta Company, Ltd.

Akira Sugimoto

Hideki Nagata

Kazuhiko Ishimaru

Hideki Kawai

Toshiharu Mori

Hiroshi Yuki

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 35 to 60 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO and from 0.1 to 1.8 wt % of P O .

Glass-ceramic composition for recording disk substrate

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 51 to 57.5 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 0.1 to 6.8 wt % of TiO .

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 48 to 54.8 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 2.4 to 10 wt % of Li O.

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 35 to 50 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 2.6 to 8 wt % of Li O.

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 54.5 to 59.5 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 3 to 12 wt % of Li O.

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 50.5 to 56 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 4.2 to 10.6 wt % of TiO .

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 47.5 to 58 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 0.1 to 2.8 wt % of ZrO .

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 47.5 to 52.5 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 6.2 to 7.8 wt % of TiO .

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 54 to 60 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 0.1 to 2.7 wt % of Li O.

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 52 to 56 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 7 to 12 wt % of TiO .

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis; from 50.5 to 52.5 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 4 to 10.6 wt % of TiO .

A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 53.5 to 60 wt % of SiO , from 10 to 30 wt % of Al O , from 10 to 30 wt % of MgO, and from 3.5 to 8.8 wt % of TiO .

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Nishinomiya, Japan

Akira Sugimoto