Magnetic nanocompass compositions and processes for making and using

• US 5,714,536 A
• Filed: 01/11/1996
• Issued: 02/03/1998
• Est. Priority Date: 01/11/1996
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Zhang, Xixiang, Ziolo, Ronald F., Palacios, Javier Tejada
• Primary Examiner(s): Jagannathan, Vasu
• Assistant Examiner(s): RAJGURU, UMAKANT K
• Application Number:
  US08/584,585
• Time in Patent Office: 754 Days
• Field of Search: 524/430, 524/439, 524/440, 524/441, 524/431, 524/432, 524/433, 524/435, 524/492, 524/493, 524/377
• US Class Current: 524/430
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: C08K 3/08 Metals
• CPC Class Codes: C08K 3/22 of metals
• CPC Class Codes: H01F 1/0063 in a non-magnetic matrix, e.g. granular solids granular films H01F10/007
• CPC Class Codes: H01F 1/445 the magnetic component being a compound, e.g. Fe3O4 H01F1/447 takes precedence

Abstract

A magnetic composition comprising nanocomposite particles comprising from about 0.001 to about 60 weight percent of magnetic nanocrystalline particles dispersed in from about 40 to about 99.999 weight percent of a discrete phase matrix, and a continuous phase matrix, wherein the discrete phase resides in interstices within the continuous phase matrix.

Claims

1. A magnetic composition comprising nanocomposite particles comprising from about 0.001 to about 60 weight percent of magnetic nanocrystalline particles selected from the group consisting of metal oxides, elemental metals and mixtures thereof, wherein the magnetic nanocrystalline particles are from about 0.0001 to about 0.1 microns in diameter and wherein the said particles are dispersed in from about 40 to about 99.999 weight percent of a discrete phase matrix selected from the group consisting of ion exchange resins, ion exchange metal oxides and mixtures thereof and continuous phase matrix selected from the group consisting of a solid, a rigid foam and a gel, wherein the discrete phase resides in the interstices within the continuous phase matrix.

2. A magnetic composition in accordance with claim 1 wherein the magnetic nanocrystalline particles are magnetically rotationally free and single domain in character.

3. A magnetic composition in accordance with claim 1 wherein the magnetic nanocrystalline particles are free of magnetic memory.

4. A magnetic composition in accordance with claim 1 wherein the continuous phase matrix is comprised of an alcohol or mixture of alcohols with from 1 to about 5 carbon atoms and which phase is at a temperature at or below the freezing point of the alcohol.

5. A magnetic composition in accordance with claim 1 wherein the continuous phase matrix is a gel comprised of a mixture of a glycol and hydrophilic fumed metal oxide particles.

6. A magnetic composition in accordance with claim 1 wherein the continuous phase matrix is an alkyl acrylate polymer.

7. A magnetic composition in accordance with claim 1 wherein the continuous phase matrix is a liquid gelled acrylic polymer.

8. A magnetic composition in accordance with claim 1 wherein the interstices are a void or voids of from about 0.001 to about 1.0 micron in diameter.

9. A magnetic composition in accordance with claim 1 wherein the interstices are a void or voids of from about 0.005 to about 0.1 microns in diameter.

10. A magnetic composition in accordance with claim 1 wherein the interstices are a void or voids of from about 0.005 to about 0.05 microns in diameter.

11. A magnetic composition in accordance with claim 1 wherein the composition is free of magnetic interaction between individual magnetic nanocrystalline particles, and individual discrete phase matrix particles.

12. A magnetic composition in accordance with claim 1 wherein the composition is free of barriers to a change in system magnetization(M).

13. A magnetic composition in accordance with claim 1 wherein the magnetic response of the composition becomes infinite up to about the saturation magnetization of the composition upon application of a magnetic field (H) of from about 10^-8 to about 10 Tesla.

14. A magnetic composition in accordance with claim 1 wherein the initial magnetic saturation is from about 0.01 emu per gram to about the bulk saturation magnetization of the composition.

15. A magnetic composition in accordance with claim 1 wherein the composition has a magnetic saturation moment of from about 0.1 to about 30 emu per gram.

16. A magnetic composition in accordance with claim 1 wherein the composition is superparamagnetic at about 4°

K. to about 500°

K. and is substantially instantaneously responsive to a magnetic field.

17. A magnetic composition in accordance with claim 1 wherein the magnetic nanocrystalline particles are formed from magnetic metal ions selected from the group consisting of transition metal elements, a lanthanide series element, and mixtures thereof.

18. A magnetic composition in accordance with claim 1 wherein the magnetic nanocrystalline particles are gamma phase iron oxide particles of from about 10 nanometers to about 0.1 microns in diameter and are uniformly dispersed in the discrete phase.

19. A magnetic composition in accordance with claim 1 wherein the composition has an initial magnetic permeability of greater than about 1.0.

20. A magnetic composition in accordance with claim 1 wherein the composition has an initial magnetic permeability of from about 1.1 to about 10⁷.

21. A magnetic composition in accordance with claim 1 wherein the composition is electrically nonconductive.

22. A magnetic composition in accordance with claim 1 wherein the composition is free of quantum tunneling of magnetization above 0°

K.

23. A magnetic composition in accordance with claim 1 further comprising magnetic nanoparticulate particles selected from the group consisting of ferromagnetic materials, ferrimagnetic materials, and mixtures thereof.

24. A magnetic composition in accordance with claim 1 wherein the nanocrystalline particles contained in the discrete phase are physically separated from the walls of the interstices formed by the continuous phase matrix.

25. A magnetic composition in accordance with claim 1 wherein the nanocomposite particles comprise from about 0.01 to about 40 weight percent of magnetic nanocrystalline particles dispersed in from about 50 to about 90 weight percent of the discrete phase matrix.