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US4810401A
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Superparamagnetic solid particles
Assignee: BASF SE
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Filing: 1987-05-28
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Granted: 1989-03-07
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Expires: 2007-05-28
Abstract
Abstract Superparamagnetic solid particles of the general formula I M.sub.v Mn.sub.w Zn.sub.x Fe.sub.y O.sub.z (I) where M is Co and/or Ni, v and w are each from 0 to 0.998, x is from 0.001 to 0.998, y is from 2.001 to 2.998, z is from 3.001 to 4, v+w+x is from 0.002 to 0.999, v+w+x+y is 3, v≠0 if w=0 and w≠0 or v=0, polar and nonpolar superparamagnetic liquids which contain the surfactant-coated superparamagnetic solid particles I in the form of a colloidal dispersion in polar or nonpolar liquid media, and processes for the preparation of polar and nonpolar superparamagnetic liquids.
Inventors
- 👤 Gunther Mair
- 👤 Werner Steck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:44
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/44; A; A61; A61K; A61K49/00; A61K49/06; A61K49/18; A61K49/1806; A61K49/1818; A61K49/1821; A61K49/1824; A61K49/1827; A61K49/1833; A61K49/1842
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
118 words
Superparamagnetic cubic ferrite particles of the formula M.sub.v Mn.sub.w Zn.sub.x Fe.sub.y O.sub.z (I) where M is selected from the group consisting of Co and Ni, v and w are each from 0 to 0.998, x is from 0.001 to 0.998, y is from 2.001 to 2.998, z is from 3.001 to 4, v+w+x is from 0.001 to 0.999, v+w+x+y is 3, v≠0 if w=0, and w≠0 if v=0; having a BET inner surface area of from 40 to 130 m 2 /g and a saturation magnetization M s of larger than 60 nTm 3 /g in a magnetic field of 160 kA/m, said particles displaying a hysteresis-free reversible magnetization and demagnetization behavior when dispersed colloidally in a liquid.
Claim 2
Dependent Claim
118 words
Superparamagnetic cubic ferrite particles of the formula M.sub.v Mn.sub.w Zn.sub.x Fe.sub.y O.sub.z (I) where M is selected from the group consisting of Co and Ni, v and w are each from 0 to 0.998, x is from 0.001 to 0.998, y is from 2.001 to 2.998, z is from 3.001 to 4, v+w+x is from 0.001 to 0.999, v+w+x+y is 3, v≠0 if w=0, and w≠0 if v=0; having a BET inner surface area of from 40 to 130 m 2 /g and a saturation magnetization M s of larger than 60 nTm 3 /g in a magnetic field of 160 kA/m, said particles displaying a hysteresis-free reversible magnetization and demagnetization behavior when dispersed colloidally in a liquid.
Claim 3
Dependent Claim
22 words
The superparamagnetic cubic ferrite particles of claim 1, having a BET inner surface area of from 50 to 120 m 2 /g.
Claim 4
Dependent Claim
22 words
The superparamagnetic cubic ferrite particles of claim 1, having a BET inner surface area of from 60 to 110 m 2 /g.
Claim 5
Dependent Claim
20 words
The superparamagnetic cubic ferrite particles of claim 1, having a maximum particle diameter of from about 5 to 15 nm.
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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) | 1992-03-06 | 1992-09-05 | 1993-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-06 | 1996-09-05 | 1997-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-06 | 2000-09-05 | 2001-03-07 | $7700.00 | Window Closed / Lapsed |