US4584242A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Plate-like barium ferrite particles for magnetic recording and process for producing the same
Assignee: Toda Kogyo Corp
•
Filing: 1985-05-28
•
Granted: 1986-04-22
•
Expires: 2005-05-28
Abstract
Abstract Disclosed herein are plate-like barium ferrite particles for magnetic recording, comprising plate-like particles represented by the formula: BaFe.sub.12-2x M.sub.x Ti.sub.x O.sub.19 wherein x is 0 to 1.2 and M represents Co (II) or Co (II) and a divalent metal ion other than Co (II), the surface of the plate-like particles being modified with magnetite represented by the formula: FeO.sub.y.Fe.sub.2 O.sub.3 wherein y is over 0 and not more than 1, and a process for producing the same.
Inventors
- 👤 Norimichi Nagai
- 👤 Norio Sugita
- 👤 Nanao Horiishi
- 👤 Masao Kiyama
- 👤 Toshio Takada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:48
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/33; B; B82; B82Y; B82Y30/00; C; C01; C01G; C01G49/00; C01G49/0018; C01G49/0036; C01G49/009; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/10; H01F1/11; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2002/70; C01P2002/72; C01P2004/00; C01P2004/20; C01P2004/60; C01P2004/62; C01P2004/64; C01P2004/80; C01P2006/00; C01P2006/12; C01P2006/42; C01P2006/60; 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
124 words
Plate-like barium ferrite particles showing a magnetization (M) of more than 40 emu/g in a magnetic field of 10 KOe, a coercive force of 300 to 1000 Oe and an average particle diameter of 0.05 to 0.3 μm, comprising plate-like particles represented by the formula: BaFe.sub.12-2x M.sub.x Ti.sub.x O.sub.19 wherein x is 0 to 1.2 and M represents Co(II) or Co(II) and a divalent metal ion other than Co(II) selected from Fe, Mn, and Zn, the surface of the plate-like particles being modified with magnetite represented by the formula: FeO.sub.y.Fe.sub.2 O.sub.3 wherein y is over 0 and not more than 1, said plate-like barium ferrite particles absent the magnetite exhibiting a magnetization of less than 40 emu/g in a magnetic field of 10 kOe.
Claim 2
Dependent Claim
124 words
Plate-like barium ferrite particles showing a magnetization (M) of more than 40 emu/g in a magnetic field of 10 KOe, a coercive force of 300 to 1000 Oe and an average particle diameter of 0.05 to 0.3 μm, comprising plate-like particles represented by the formula: BaFe.sub.12-2x M.sub.x Ti.sub.x O.sub.19 wherein x is 0 to 1.2 and M represents Co(II) or Co(II) and a divalent metal ion other than Co(II) selected from Fe, Mn, and Zn, the surface of the plate-like particles being modified with magnetite represented by the formula: FeO.sub.y.Fe.sub.2 O.sub.3 wherein y is over 0 and not more than 1, said plate-like barium ferrite particles absent the magnetite exhibiting a magnetization of less than 40 emu/g in a magnetic field of 10 kOe.
Claim 3
Dependent Claim
215 words
A process for producing plate-like barium ferrite particles for use in magnetic recording comprising; mixing plate-like barium ferrite particles exhibiting a magnetization of less than 40 emu/g in a magnetic field of 10 KOe and represented by the formula: BaFe 12-2x M x Ti x O 19 wherein x is 0 to 1.2 and M represents Co(II) or Co(II) and a divalent, metal ion other than Co (II) selected from Fe, Mn and Zn with an aqueous alkaline suspension of Fe(OH) 2 of a pH of 8.0 to 14 containing at least 0.1 and not more than 50 atomic % of Fe(II) to total Fe(III) of said plate-like particles, and thermally treating the thus prepared aqueous mixture at a temperature of 50° to 100° C. in a non-oxidative atmosphere, whereby the surface of said plate-like particles of BaFe 12-2x M x Ti x O 19 wherein x and M are as defined above is modified with a magnetite of FeO y .Fe 2 O 3 wherein y is over 0 and not more than 1, said surface modified plate-like barium ferrite particles exhibiting a magnetization of more than 40 emu/g in a magnetic field of 10 KOe, a coercieve force of 300 to 1000 Oe and an average particle diameter of 0.05 to 0.3 μm.
Claim 4
Dependent Claim
215 words
A process for producing plate-like barium ferrite particles for use in magnetic recording comprising; mixing plate-like barium ferrite particles exhibiting a magnetization of less than 40 emu/g in a magnetic field of 10 KOe and represented by the formula: BaFe 12-2x M x Ti x O 19 wherein x is 0 to 1.2 and M represents Co(II) or Co(II) and a divalent, metal ion other than Co (II) selected from Fe, Mn and Zn with an aqueous alkaline suspension of Fe(OH) 2 of a pH of 8.0 to 14 containing at least 0.1 and not more than 50 atomic % of Fe(II) to total Fe(III) of said plate-like particles, and thermally treating the thus prepared aqueous mixture at a temperature of 50° to 100° C. in a non-oxidative atmosphere, whereby the surface of said plate-like particles of BaFe 12-2x M x Ti x O 19 wherein x and M are as defined above is modified with a magnetite of FeO y .Fe 2 O 3 wherein y is over 0 and not more than 1, said surface modified plate-like barium ferrite particles exhibiting a magnetization of more than 40 emu/g in a magnetic field of 10 KOe, a coercieve force of 300 to 1000 Oe and an average particle diameter of 0.05 to 0.3 μm.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-04-21 | 1989-10-21 | 1990-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-21 | 1993-10-21 | 1994-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-21 | 1997-10-21 | 1998-04-22 | $7700.00 | Window Closed / Lapsed |