US4851292A
Expired / Lapsed
US
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Plate-like barium ferrite particles suitable for use in magnetic recording and process for producing the same
Assignee: Toda Kogyo Corp
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Filing: 1987-01-29
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Granted: 1989-07-25
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Expires: 2007-01-29
Abstract
Abstract Disclosed herein are plate-like barium ferrite particles with a solid solution of zinc on the surface thereof, which have an average particle diameter of not less than 0.03 μm and less than 0.1 μm, a BET specific surface are of 55 to 80 m 2 /g, a coercive force of 300 to 1,500 Oe and a magnetization of not less than 57 emu/g, preferably not less than 60 emu/g, in magnetic field of 10 KOe, and which are represented by the following formula (I): BaO.n[(Fe.sub.1-x-y Co.sub.x Ti.sub.y).sub.2 O.sub.3-x+y ] (I) wherein x and y are independently from 0.02 to 0.12 and n is from 4 to 11, the atomic ratio of Co to Fe(III) being from 0.02:1 to 0.13:1 and the molar ratio of Ti to Co being from more than 0 to not more than 0.8, and a process for producing the plate-like barium ferrite particles.
Inventors
- 👤 Norimichi Nagai
- 👤 Akihiko Hirayama
- 👤 Norio Sugita
- 👤 Masao Kiyama
- 👤 Toshio Takada
- 👤 Katsunori Fujimoto
- 👤 Yasutaka Ota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 01:25
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/10; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
157 words
Plate-like barium ferrite particles with a solid solution of zinc on the surface thereof, which have an average particle diameter of not less than 0.03 μm and less than 0.1 μm, 0.2 to 5.0 wt % of the solid solution of zinc with respect to the plate-like barium ferrite particles with the solid solution of zinc on the surface thereof, a BET specific surface area of 55 to 80 m 2 /g, a coercive force of 300 to 1,500 Oe and a magnetization of not less than 57 emu/g in magnetic field of 10 KOe, and which are represented by the following formula (I): BaO·n[(Fe.sub.1-x-y Co.sub.x Ti.sub.y).sub.2 O.sub.3-x+y ](I) wherein x and y are independently from 0.02 and 0.12 and n is from 4 to 11, the atomic ratio of Co to Fe (III) being from 0.02:1 to 0.13:1 and the molar ratio of Ti to Co being from more than 0 to not more than 0.8.
Claim 2
Dependent Claim
157 words
Plate-like barium ferrite particles with a solid solution of zinc on the surface thereof, which have an average particle diameter of not less than 0.03 μm and less than 0.1 μm, 0.2 to 5.0 wt % of the solid solution of zinc with respect to the plate-like barium ferrite particles with the solid solution of zinc on the surface thereof, a BET specific surface area of 55 to 80 m 2 /g, a coercive force of 300 to 1,500 Oe and a magnetization of not less than 57 emu/g in magnetic field of 10 KOe, and which are represented by the following formula (I): BaO·n[(Fe.sub.1-x-y Co.sub.x Ti.sub.y).sub.2 O.sub.3-x+y ](I) wherein x and y are independently from 0.02 and 0.12 and n is from 4 to 11, the atomic ratio of Co to Fe (III) being from 0.02:1 to 0.13:1 and the molar ratio of Ti to Co being from more than 0 to not more than 0.8.
Claim 3
Dependent Claim
32 words
Plate-like barium ferrite particles according to claim 1, wherein the atomic ratio of Co to Fe(III) is 0.04:1 to 0.10:1 and the molar ratio of Ti to Co is 0.1 to 0.7.
Claim 4
Dependent Claim
17 words
Plate-like barium ferrite particles according to claim 1, wherein a magnetization is not less than 60 emu/g.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-24 | 1993-01-23 | 1993-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-24 | 1997-01-23 | 1997-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-24 | 2001-01-23 | 2001-07-25 | $7700.00 | Window Closed / Lapsed |