US4698182A
Expired / Lapsed
US
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Hexagonal plate-like barium ferrite particles for magnetic recording and process for producing the same
Assignee: Toda Kogyo Corp
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Filing: 1984-09-24
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Granted: 1987-10-06
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Expires: 2004-09-24
Abstract
Abstract Disclosed herein are hexagonal plate-like barium ferrite particles for magnetic recording, represented by the formula: BaFe 12-x-y M x Ti y O 19 wherein x and y are independently 0.6 to 1.2 and M is Co(II) or Co(II) and a divalent metal other than Co, having the width of the particle of 0.1 to 0.4 micrometer and a BET specific surface area (S) of 20 to 50 m 2 /g, and showing a magnetization (M) of larger than 40 emu/g in a magnetic field of 10 KOe and a coercive force (Hc) of 500 to 1000 Oe, 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
2026-10-25 22:44
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/714; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678; G11B5/84
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
199 words
A process for producing hexagonal plate-like barium ferrite particles for magnetic recording, represented by the formula (I): BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 (I) wherein x and y are independently 0.6 to 1.2 and M is Co(II) or Co(II) and a divalent metal of Fe(II), Zn(II) or Mn(II), having the width of said particle of 0.1 to 0.4 um and a BET specific surface area (S) of 30 to 50 m 2/ g, and showing a magnetization (M) of larger than 40 emu/g in a magnetic field of 10 KOe and a coercive force (Hc) of 500 to 1000 Oe, which process comprising autoclaving an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) and a divalent metal of Fe(II), Zn(II) or Mn(II) as M at a temperature in the range of from 250° to 330° C. to form ferromagnetic hexagonal plate-like particles of the formula (I) wherein x, y and M are the same as defined above and having a width of said particles of 0.04 to 0.4 um, treating the thus obtained particles with an aqueous solution containing Si(IV), and subjecting the thus treated particles to thermal treatment at a temperature of 700° to 900° C.
Claim 2
Dependent Claim
199 words
A process for producing hexagonal plate-like barium ferrite particles for magnetic recording, represented by the formula (I): BaFe.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 (I) wherein x and y are independently 0.6 to 1.2 and M is Co(II) or Co(II) and a divalent metal of Fe(II), Zn(II) or Mn(II), having the width of said particle of 0.1 to 0.4 um and a BET specific surface area (S) of 30 to 50 m 2/ g, and showing a magnetization (M) of larger than 40 emu/g in a magnetic field of 10 KOe and a coercive force (Hc) of 500 to 1000 Oe, which process comprising autoclaving an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) and a divalent metal of Fe(II), Zn(II) or Mn(II) as M at a temperature in the range of from 250° to 330° C. to form ferromagnetic hexagonal plate-like particles of the formula (I) wherein x, y and M are the same as defined above and having a width of said particles of 0.04 to 0.4 um, treating the thus obtained particles with an aqueous solution containing Si(IV), and subjecting the thus treated particles to thermal treatment at a temperature of 700° to 900° C.
Claim 3
Dependent Claim
21 words
A process according to claim 1, wherein the thermal treatment is carried out at a temperature of 700° to 850° C.
Claim 4
Dependent Claim
29 words
A process according to claim 1, wherein in the aqueous highly alkaline suspension the atomic ratio of total sum of M and Ti(IV) to Fe(III) is 0.11:1 to 0.25:1.
Claim 5
Dependent Claim
22 words
A process according to claim 1, wherein ferric chloride, ferric nitrate or powdery ferric oxyhydroxide is used as a source of Fe(III).
Claim 6
Dependent Claim
21 words
A process according to claim 1, wherein barium hydroxide, barium nitrate or barium choride is used as a source of Ba(II).
Claim 7
Dependent Claim
19 words
A process according to claim 1, wherein cobalt nitrate or cobalt chloride is used as a source of Co(II).
Claim 8
Dependent Claim
19 words
A process according to claim 1, wherein titanium chloride of alkali titanate is used as a source of Ti(IV).
Claim 9
Dependent Claim
12 words
A process according to claim 1, wherein x is equal to y.
Claim 10
Dependent Claim
192 words
Hexagonal plate-like barium ferrite particles for magnetic recording, represented by the formula(I): BaFE.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 (I) wherein x and y are independently 0.6 to 1.2 and M is Co(II) or Co(II) and a divalent metal of Fe(II), Zn(II) or Mn(II), having the width of the particle of 0.1 to 0.4 um and a BET specific surface area (S) of 30 to 50 m2/g, and showing a magnetization (M) of larger than 40 emu/g in a magnetic filed of 10 KOe and a coercive force (Hc) of 500 to 1000 Oe, produced by autoclaving an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) or Co(II) and said divalent metal of Fe(II), Zn(II) or Mn(II) as M at a temperature in the range of from 250° to 330° C., thereby obtaining ferromagnetic hexagonal plate-like particles represented by the formula (I) wherein x,y and M are the same as defined above, having the width of said particles of 0.05 to 0.4 um, treating the thus obtained particles with an aqueous solution containing Si(IV) and subjecting the thus treated particles to thermal treatment at a temperature of 700° to 900° C.
Claim 11
Dependent Claim
192 words
Hexagonal plate-like barium ferrite particles for magnetic recording, represented by the formula(I): BaFE.sub.12-x-y M.sub.x Ti.sub.y O.sub.19 (I) wherein x and y are independently 0.6 to 1.2 and M is Co(II) or Co(II) and a divalent metal of Fe(II), Zn(II) or Mn(II), having the width of the particle of 0.1 to 0.4 um and a BET specific surface area (S) of 30 to 50 m2/g, and showing a magnetization (M) of larger than 40 emu/g in a magnetic filed of 10 KOe and a coercive force (Hc) of 500 to 1000 Oe, produced by autoclaving an aqueous highly alkaline suspension of ferric hydroxide containing Ti(IV), Ba(II) and Co(II) or Co(II) and said divalent metal of Fe(II), Zn(II) or Mn(II) as M at a temperature in the range of from 250° to 330° C., thereby obtaining ferromagnetic hexagonal plate-like particles represented by the formula (I) wherein x,y and M are the same as defined above, having the width of said particles of 0.05 to 0.4 um, treating the thus obtained particles with an aqueous solution containing Si(IV) and subjecting the thus treated particles to thermal treatment at a temperature of 700° to 900° C.
Claim 12
Dependent Claim
23 words
Hexagonal plate-like barium ferrite particles according to claim 9, wherein the thermal treatment is carried out at temperature a 700° to 850° C.
Claim 13
Dependent Claim
27 words
Hexagonal plate-like barium ferrite particles according to claim 10, wherein the BET specific surface area thereof is in the range of 30 to 45 m 2 /g.
Claim 14
Dependent Claim
24 words
Hexagonal plate-like barium ferrite particles according to claim 10, wherein the width of the particle is in the range of 0.1 to 0.3 micrometer.
Claim 15
Dependent Claim
23 words
Hexagonal plate-like barium ferrite particles according to claim 10, wherein the coercive force (Hc) is in the range of 600 to 900 Oe.
Claim 16
Dependent Claim
15 words
Hexagonal plate-like barium ferrite particles according to claim 10, wherein x is equal to y.
Claim 17
Dependent Claim
32 words
Hexagonal plate-like barium ferrite particles according to claim 10, wherein in the aqueous highly alkaline suspension the atomic ratio of total sum of M and Ti(IV) to Fe(III) is 0.11:1 to 0.25:1.
References Cited (Backward Citations)
US4341648A
Cited
US4309459A
Cited
US4414124A
Cited
JPS5756904A
Cited
JPS57198604A
Cited
JPS5856303A
Cited
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