US4778734A
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Barium ferrite magnetic powder and magnetic recording medium containing the same
Assignee: Ube Corp
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Filing: 1988-02-01
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Granted: 1988-10-18
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Expires: 2008-02-01
Abstract
Abstract A hexagonal magnetoplumbite-type barium ferrite magnetic powder represented by the following formula BaO.n(Fe12-x-y-zMx1MY2ZnzO18- alpha ) wherein M1 represents at least one metal element selected from Co, Ni, Cu, Mg, and Mn; M2 represents at least one metal element selected from Zr, Ti, and Ge; n is a number of from 0.8 to 1.0; x is a number of from 0.1 to 2.5; y is a number of from 0.1 to 1.5; x is a number of from 0.1 to 1.5; and alpha is 1/2(3-m)(x+y+z) in which m is a number of less than 3 and represents an average atomic valence of M1, M2 and Zn. The said hexagonal magnetoplumbite-type barium ferrite is useful for a magnetic recording medium.
Inventors
- 👤 Kyoji Ohdan
- 👤 Takayuki Kimura
- 👤 Hiroshi Miura
- 👤 Kazuo Hashimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:05
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2608; C04B35/2633; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; Y; Y10; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
156 words
A hexagonal magnetoplumbite barium ferrite magnetic powder represented by the following formula BaO.n(Fe.sub.12-x-y-z M.sub.x.sup.1 M.sub.y.sup.2 Zn.sub.z O.sub.18-α) wherein M 1 represents at least one metal element selected from Co, Ni, Cu, Mg and Mn; M 2 represents at least one metal element selected from Zr, Ti and Ge; n is a number of from 0.8 to 1.0; x is a number of from 0.1 to 2.5; y is a number of from 0.1 to 1.5; z is a number of from 0.1 to 1.5; and α is 1/2 (3-m) (x+y+z) in which m is a number of 2.2 to 2.8 and represents an average atomic valence of M 1 , M 2 and Zn, wherein said hexagonal magnetoplumbite barium ferrite magnetic powder has the characteristics specific surface area: 20 to 70 m 2 /g coercive force: 200 to 2,000 Oe saturation magnetization: ≧55 emu/g average particle diameter: 100 to 30 nm aspect ratio: 2 to 15.
Claim 2
Dependent Claim
156 words
A hexagonal magnetoplumbite barium ferrite magnetic powder represented by the following formula BaO.n(Fe.sub.12-x-y-z M.sub.x.sup.1 M.sub.y.sup.2 Zn.sub.z O.sub.18-α) wherein M 1 represents at least one metal element selected from Co, Ni, Cu, Mg and Mn; M 2 represents at least one metal element selected from Zr, Ti and Ge; n is a number of from 0.8 to 1.0; x is a number of from 0.1 to 2.5; y is a number of from 0.1 to 1.5; z is a number of from 0.1 to 1.5; and α is 1/2 (3-m) (x+y+z) in which m is a number of 2.2 to 2.8 and represents an average atomic valence of M 1 , M 2 and Zn, wherein said hexagonal magnetoplumbite barium ferrite magnetic powder has the characteristics specific surface area: 20 to 70 m 2 /g coercive force: 200 to 2,000 Oe saturation magnetization: ≧55 emu/g average particle diameter: 100 to 30 nm aspect ratio: 2 to 15.
Claim 3
Dependent Claim
29 words
The magnetic powder of claim 1 wherein M 1 is Co or a combination of Co with at least one metal element selected from Ni, Cu, Mg and Mn.
Claim 4
Dependent Claim
46 words
The magnetic powder of claim 2 wherein M 1 represents (Co k M 1-k 3 ) in which M 3 represents at least one metal element selected from Ni, Cu, Mg and Mn, and k is a number of more than 0 but less than 1.
Claim 5
Dependent Claim
16 words
The magnetic powder of claim 3 wherein M 3 is Ni and M 2 is Ti.
Claim 6
Dependent Claim
11 words
The magnetic powder of claim 1 wherein M 2 is Ti.
Claim 7
Dependent Claim
15 words
The magnetic powder of claim 1 wherein x is a number of 0.5 to 2.
Claim 8
Dependent Claim
15 words
The magnetic powder of claim 1 wherein y is a number of 0.1 to 1.0.
Claim 9
Dependent Claim
15 words
The magnetic powder of claim 1 wherein z is a number of 0.3 to 1.2.
Claim 10
Dependent Claim
15 words
The magnetic powder of claim 1 wherein x+y+z is a number of 1 to 4.
Claim 11
Dependent Claim
26 words
A magnetic recording medium comprising a support and a magnetic recording medium layer containing the hexagonal magnetoplumbite barium ferrite magnetic power set forth in claim 1.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-10-18 | 1992-04-18 | 1992-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-18 | 1996-04-18 | 1996-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-18 | 2000-04-18 | 2000-10-18 | $7700.00 | Window Closed / Lapsed |