Hexagonal ferrite magnetic powder and method of manufacturing the same, and magnetic recording medium and method of manufacturing the same
AssigneesFUJIFILM Corporation, Asahi Glass Company, Limited
InventorsSatoshi MATSUBAGUCHI, Ayako Matsumoto, Toshio Tada, Akira Manabe
Life of this patent
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Abstract
An aspect of the present invention relates to a hexagonal ferrite magnetic powder manufactured by a glass crystallization method as well as having an average plate diameter ranging from 15 to 25 nm, an average plate ratio ranging from 2.0 to 2.8 and a coercive force (Hc) ranging from 159 to 279 kA/m.
Claims16
A hexagonal ferrite magnetic powder manufactured by a glass crystallization method as well as having an average plate diameter ranging from 15 to 25 nm, an average plate ratio ranging from 2.0 to 2.8 and a coercive force (Hc) ranging from 159 to 279 kA/m.
A method of manufacturing a hexagonal ferrite magnetic powder comprising:
- preparing a melt by melting a starting material mixture comprising a glass-forming component and a hexagonal ferrite-forming component;
- rapidly cooling the melt to obtain a solid;
- and
- heating the solid to precipitate a hexagonal ferrite magnetic powder, wherein
- the hexagonal ferrite-forming component comprises, as a component substituting for Fe, just a pentavalent element component selected from the group consisting of Nb2O5 component and Ta2O5 component, and
- the starting material mixture comprises a pentavalent element selected from the group consisting of Nb and Ta in a quantity of equal to or greater than 2.5 atomic percent when a sum of the pentavalent element and Fe is adopted as 100 atomic percent.
A magnetic recording medium comprising a magnetic layer comprising a hexagonal ferrite magnetic powder and a binder on a nonmagnetic support, wherein
- the hexagonal ferrite magnetic powder is one manufactured by a glass crystallization method as well as having an average plate diameter ranging from 15 to 25 nm, an average plate ratio ranging from 2.0 to 2.8 and a coercive force (Hc) ranging from 159 to 279 kA/m.
A method of manufacturing a magnetic recording medium comprising:
- manufacturing a hexagonal ferrite magnetic powder;
- and
- forming a magnetic layer using the hexagonal ferrite magnetic powder manufactured, wherein the hexagonal ferrite magnetic powder manufactured by:
- preparing a melt by melting a starting material mixture comprising a glass-forming component and a hexagonal ferrite-forming component;
- rapidly cooling the melt to obtain a solid;
- heating the solid to precipitate a hexagonal ferrite magnetic powder, wherein
- the hexagonal ferrite-forming component comprises, as a component substituting for Fe, just a pentavalent element component selected from the group consisting of Nb2O5 component and Ta2O5 component, and
- the starting material mixture comprises a pentavalent element selected from the group consisting of Nb and Ta in a quantity of equal to or greater than 2.5 atomic percent when a sum of the pentavalent element and Fe is adopted as 100 atomic percent.
Dependencies are inferred from the claim text.