Title:
SPINEL TYPE FERRIMAGNETIC POWDER AND MAGNETIC RECORDING MEDIUM
Document Type and Number:
WIPO Patent Application WO/2004/100190
Kind Code:
A1
Abstract:
A magnetic material that while maintaining a high coercive force, has a low content of superparamagnetic powder and exhibits excellent magnetic properties upon use in a recording medium. In particular, a spinel type ferrimagnetic powder whose composition at charging is expressed by the formula (CoO)0.5-x(NiO)0.5-y(MO)x+y·n/2(Fe2O3) in which M represents a bivalent metal excluding Co and Ni; the value of n = Fe/(Co + Ni + Zn) (molar ratio) is greater than the stoichiometric quantity of spinel type ferrite (n = 2) but less than 1.5 times the stoichiometric quantity and satisfies the relationship 0 < n < 3.0; and the values of x and y satisfy the relationships 0 ≤ x < 0.5, 0 ≤ y < 0.5 and 0 < x + y < 0.5. The content of superparamagnetic powder in the spinel type ferrimagnetic powder is 5 mass% or less.
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Inventors:
YAMAMOTO HIROSHI (JP)
WAKAMURA NATSUKI (JP)
YOSHIDA NAOKI (JP)
WAKAMURA NATSUKI (JP)
YOSHIDA NAOKI (JP)
Application Number:
PCT/JP2003/013240
Publication Date:
November 18, 2004
Filing Date:
October 16, 2003
Export Citation:
Assignee:
UNIV MEIJI LEGAL PERSON (JP)
YAMAMOTO HIROSHI (JP)
WAKAMURA NATSUKI (JP)
YOSHIDA NAOKI (JP)
YAMAMOTO HIROSHI (JP)
WAKAMURA NATSUKI (JP)
YOSHIDA NAOKI (JP)
International Classes:
C01G49/00; C01G53/00; G11B5/706; H01F1/11; (IPC1-7): H01F1/11; G11B5/706; C01G53/00
Foreign References:
| JPH0113813A | ||||
| JPH0645129A | 1994-02-18 | |||
| JPS527160B1 | 1977-02-28 | |||
| JPS5078599A | 1975-06-26 | |||
| JPH07267645A | 1995-10-17 | |||
| JPH06224020A | 1994-08-12 | |||
| JPH08119635A | 1996-05-14 | |||
| JPH07315844A | 1995-12-05 | |||
| JPS6311525A | 1988-01-19 |
Attorney, Agent or Firm:
Takahashi, Isamu (Shinoda Bldg. 10-7, Higashi Kanda 1-chom, Chiyoda-ku Tokyo, JP)
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