| US 7,399,523 B2 | ||
| Spinel ferrimagnetic particles and magnetic recording medium | ||
| Hiroshi Yamamoto, Kanagawa (Japan); Natsuki Wakamura, Kanagawa (Japan); and Naoki Yoshida, Kanagawa (Japan) | ||
| Assigned to Meiji University Legal Person, Tokyo (Japan) | ||
| Appl. No. 10/530,330 PCT Filed Oct. 16, 2003, PCT No. PCT/JP03/13240 § 371(c)(1), (2), (4) Date Apr. 05, 2005, PCT Pub. No. WO2004/100190, PCT Pub. Date Nov. 18, 2004. |
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| Claims priority of application No. 2003-129274 (JP), filed on May 07, 2003. | ||
| Prior Publication US 2006/0292403 A1, Dec. 28, 2006 | ||
| Int. Cl. B32B 5/16 (2006.01) | ||
| U.S. Cl. 428—329 [428/407] | 7 Claims |
| 1. Spinel ferrimagnetic particles, a composition formula 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), where,
a value of n (molar ratio)=Fe/(Co+Ni+M) 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 said x, y satisfy 0≤x<0.5, 0≤y<0.5, 0<x+y<0.5, wherein,
also, superparamagnetic fine particles contained in said spinel ferrimagnetic particles produced by coprecipitation is 5%
by mass or less.
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