Spinel ferrimagnetic particles and magnetic recording medium

Details Spinel ferrimagnetic particles and magnetic recording medium Spinel ferrimagnetic particles and magnetic recording medium

2008-07-15

2008-07-15

Hendricks, Keith D. (Department: 1794)

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Web or sheet containing structurally defined element or...

Including a second component containing structurally defined...

C428S407000

Reexamination Certificate

active

07399523

ABSTRACT:
Provided is a magnetic material with excellent magnetic properties to be used for recording media, which contains small ratio of superparamagnetic fine particles while maintaining high coercivity. It is spinel ferrimagnetic particles, a composition equation of which when prepared is (CoO)0.5-x(NiO)0.5-y(MO)x+y.n/2(Fe2O3) (M is a bivalent metal except Co and Ni) and a value of n (molar ratio)=Fe/(Co+Ni+Zn) is 2.0<n<3.0, which is larger than stoichiometric amount (n=2) of a spinel ferrite and less than that of 1.5 times, and values of x, y satisfy 0≦x<0.5, 0≦y<0.5, 0<x+y<0.5, wherein, also, superparamagnetic fine particles contained in the spinel ferrimagnetic particles is 5% by mass or less.

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