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US4585568A
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Plate-like barium ferrite particles for magnetic recording and process for producing the same
Assignee: Toda Kogyo Corp
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Filing: 1984-03-14
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Granted: 1986-04-29
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Expires: 2004-03-14
Abstract
Abstract Disclosed herein are plate-like barium ferrite particles having BET specific surface area of 20 to 70 m 2 /g and average particle diameter of 0.05 to 0.3 μm, and showing a magnetization of higher than 30 emu/g in a field of 10 kOe and coercive force of 300 to 1,000 Oe, represented by the formula BaCo x Ti x Fe 12-2x O 19 wherein x is 0.1 to 0.5, and a process for producing the same.
Inventors
- 👤 Norimichi Nagai
- 👤 Nanao Horiishi
- 👤 Masao Kiyama
- 👤 Toshio Takada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:27
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
70 words
Plate-like barium ferrite particles represented by the formula BaCo x Ti x Fe 12-2x O 19 wherein x is 0.1 to 0.5, having a BET specific surface area of 20 to 70 m 2 /g and an average particle diameter of 0.05 to 0.3 μm, and showing a magnetization of larger than 30 emu/g in a magnetic field of 10 kOe and a coercive force of 300 to 1,000 Oe.
Claim 2
Dependent Claim
70 words
Plate-like barium ferrite particles represented by the formula BaCo x Ti x Fe 12-2x O 19 wherein x is 0.1 to 0.5, having a BET specific surface area of 20 to 70 m 2 /g and an average particle diameter of 0.05 to 0.3 μm, and showing a magnetization of larger than 30 emu/g in a magnetic field of 10 kOe and a coercive force of 300 to 1,000 Oe.
Claim 3
Dependent Claim
25 words
Plate-like barium ferrite particles according to claim 1, wherein BET specific surface area thereof is in the range of 45 to 65 m 2 /g.
Claim 4
Dependent Claim
22 words
Plate-like barium ferrite particles according to claim 1, wherein said average particle diameter is in the range of 0.05 to 0.25 μm.
Claim 5
Dependent Claim
21 words
Plate-like barium ferrite particles according to claim 1, wherein said coercive force is in the range of 400 to 800 Oe.
Claim 6
Dependent Claim
142 words
Process for producing plate-like barium ferrite particles represented by the formula: BaCo.sub.x Ti.sub.x Fe.sub.12-2x O.sub.19 wherein x is 0.1 to 0.5, having a BET specific surface area of 20 to 70 m 2 /g and an average particle diameter of 0.05 to 0.3 μm, and showing a magnetization of larger than 30 emu/g in the magnetic field of 10 KOe and a coercive force of 300 to 1,000 Oe, which comprises autoclaving an aqueous highly alkaline suspension containing Fe(III), Co(II), Ti(IV) and Ba ions at a temperature of 250° to 320° C., the atomic ratio of total amount of Co(II) and Ti(IV) to the amount of Fe(III) being 0.017:1 to 0.09:1, the amount of Co(II) being the same as that of Ti(IV) and the atomic ratio of Ba ions to the total sum of Fe(III), Co(II) and Ti(IV) being 1:7 to 1:9.
Claim 7
Dependent Claim
142 words
Process for producing plate-like barium ferrite particles represented by the formula: BaCo.sub.x Ti.sub.x Fe.sub.12-2x O.sub.19 wherein x is 0.1 to 0.5, having a BET specific surface area of 20 to 70 m 2 /g and an average particle diameter of 0.05 to 0.3 μm, and showing a magnetization of larger than 30 emu/g in the magnetic field of 10 KOe and a coercive force of 300 to 1,000 Oe, which comprises autoclaving an aqueous highly alkaline suspension containing Fe(III), Co(II), Ti(IV) and Ba ions at a temperature of 250° to 320° C., the atomic ratio of total amount of Co(II) and Ti(IV) to the amount of Fe(III) being 0.017:1 to 0.09:1, the amount of Co(II) being the same as that of Ti(IV) and the atomic ratio of Ba ions to the total sum of Fe(III), Co(II) and Ti(IV) being 1:7 to 1:9.
Claim 8
Dependent Claim
20 words
A process according to claim 5, wherein the source of Fe(III) is ferric chloride, ferric nitrate or powdery ferric oxyhydroxide.
Claim 9
Dependent Claim
18 words
A process according to claim 5, wherein the source of Ba ions is barium hydroxide or barium oxide.
Claim 10
Dependent Claim
17 words
A process according to claim 5, wherein the source of Co(II) is cobalt nitrate or cobalt chloride.
Claim 11
Dependent Claim
17 words
A process according to claim 5, wherein the source of Ti(IV) is titanium chloride or alkali titanate.
Claim 12
Dependent Claim
142 words
Plate-like barium ferrite particles for magnetic recording, represented by the formula BaCo x Ti x Fe 12-2x O 19 wherein x is 0.1 to 0.5, having BET specific surface area of 20 to 70 m 2 /g and average particle diameter of 0.05 to 0.3 μm, and showing magnetization of larger than 30 emu/g in the magnetic field of 10 KOe and coercive force of 300 to 1,000 Oe, produced by autoclaving an aqueous highly alkaline suspension containing Fe(III), Co(II), Ti(IV) and Ba ions at a temperature of 250° to 320° C., the atomic ratio of total amount of Co(II) and Ti(IV) to the amount of Fe(III) being 0.017:1 to 0.09:1, the amount of Co(II) being the same as that of Ti(IV) and the atomic ratio of Ba ions to the total sum of Fe(III), Co(II) and Ti(IV) being 1:7 to 1:9.
Claim 13
Dependent Claim
142 words
Plate-like barium ferrite particles for magnetic recording, represented by the formula BaCo x Ti x Fe 12-2x O 19 wherein x is 0.1 to 0.5, having BET specific surface area of 20 to 70 m 2 /g and average particle diameter of 0.05 to 0.3 μm, and showing magnetization of larger than 30 emu/g in the magnetic field of 10 KOe and coercive force of 300 to 1,000 Oe, produced by autoclaving an aqueous highly alkaline suspension containing Fe(III), Co(II), Ti(IV) and Ba ions at a temperature of 250° to 320° C., the atomic ratio of total amount of Co(II) and Ti(IV) to the amount of Fe(III) being 0.017:1 to 0.09:1, the amount of Co(II) being the same as that of Ti(IV) and the atomic ratio of Ba ions to the total sum of Fe(III), Co(II) and Ti(IV) being 1:7 to 1:9.
Claim 14
Dependent Claim
25 words
Plate-like barium ferrite particles according to claim 10, wherein said BET specific surface area is in the range of 45 to 65 m 2 /g.
Claim 15
Dependent Claim
22 words
Plate-like barium ferrite particles according to claim 10, wherein said average particle diameter is in the range of 0.05 to 0.25 μm.
Claim 16
Dependent Claim
21 words
Plate-like barium ferrite particles according to claim 10, wherein said coercive force is in the range of 400 to 800 Oe.
References Cited (Backward Citations)
JPS56155023A
Cited
US4414124A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-04-28 | 1989-10-28 | 1990-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-28 | 1993-10-28 | 1994-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-28 | 1997-10-28 | 1998-04-29 | $7700.00 | Window Closed / Lapsed |