# US 11,309,107 B2 · Anisotropic iron nitride permanent magnets

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- Number: US 11,309,107 B2
- Document ID: US11309107B2
- Status: Granted
- Kind: B2
- Application number: 17/182,066
- Filed: 2021-02-22
- Published: 2021-08-26
- Granted: 2022-04-19
- Earliest claimed: 2020-02-21
- Assignees: Niron Magnetics, Inc.
- Applicants: Niron Magnetics, Inc.
- Inventors: Francis Johnson; Richard W. Greger; John M. Larson; Yiming Wu; Fan Zhang; Kathryn Sara Damien
- Web page: https://patentgrep.com/patent/US11309107B2

## CPC

- H01F 1/047: Alloys characterised by their composition
- H01F 1/0045: {Zero dimensional, e.g. nanoparticles, soft nanoparticles for medical/biological use (preparation of fullerenes in general C01B32/15)}
- H01F 1/065: {obtained by a reduction}
- H01F 1/442: {the magnetic component being a metal or alloy, e.g. Fe (H01F1/447 takes precedence)}
- H01F 41/0273: {Imparting anisotropy (methods and devices for magnetising permanent magnets H01F13/003)}
- C01P 2004/64: Nanometer sized, i.e. from 1-100 nanometer
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

Disclosed herein is a permanent magnet comprising: a plurality of aligned iron nitride nanoparticles wherein the iron nitride nanoparticles include α″-Fe16N2 phase domains; wherein a ratio of integrated intensities of an α″-Fe16N2 (004) x-ray diffraction peak to an α″-α″-Fe16N2 (202) x-ray diffraction peak for the aligned iron nitride nanoparticles is greater than at least 7%, wherein the diffraction vector is parallel to alignment direction, and wherein the iron nitride nanoparticles exhibit a squareness measured parallel to the alignment direction that is greater than a squareness measured perpendicular to the alignment direction.

## Claims

### Claim 1

A permanent magnet, comprising:
a plurality of aligned iron nitride nanoparticles wherein the iron nitride nanoparticles include α″-Fe16N2 phase domains;
wherein a ratio of integrated intensities of an α″-Fe16N2 (004) x-ray diffraction peak to an α″-Fe16N2 (202) x-ray diffraction peak is greater than 0.19, where the diffraction vector is parallel to alignment direction, and
wherein the iron nitride nanoparticles exhibit a squareness measured parallel to the alignment direction that is greater than a squareness measured perpendicular to the alignment direction.

### Claim 2 (depends on 1)

The permanent magnet of claim 1, wherein the aligned nanoparticles are configured as a wire, a sheet, or a tape, and wherein the wire, sheet, or tape are bonded to provide the permanent magnet.

### Claim 3 (depends on 1)

The permanent magnet of claim 1, wherein a ratio of integrated intensities of an α″-Fe16N2 (004) x-ray diffraction peak to an α″-Fe16N2 (202) x-ray diffraction peak is greater than at least 50%.

### Claim 4 (depends on 1)

The permanent magnet of claim 1, wherein a ratio of integrated intensities of an α″-Fe16N2 (004) x-ray diffraction peak to an α″-Fe16N2 (202) x-ray diffraction peak is greater than at least 100%.

### Claim 5 (depends on 1)

The permanent magnet of claim 1, wherein the iron nitride nanoparticles exhibit a squareness measured parallel to the alignment direction that is greater than 0.50.

### Claim 6 (depends on 1)

The permanent magnet of claim 1, wherein the iron nitride nanoparticles exhibit a squareness measured parallel to the alignment direction that is greater than 0.75.

### Claim 7 (depends on 1)

The permanent magnet of claim 1, wherein the iron nitride nanoparticles exhibit a squareness measured parallel to the alignment direction that is greater than 0.9.

### Claim 8

A nanocomposite, comprising:
a population of aligned anisotropic nanoparticles, the nanoparticles comprising an α″-Fe16N2 phase; and
a binder,
wherein the nanocomposite exhibits a squareness measured in a parallel direction that is larger than a squareness observed in a perpendicular direction to the direction of alignment of the anisotropic nanoparticles, and
wherein the nanocomposite exhibits an X-ray diffraction pattern having an intensity of an α″-Fe16N2 (004) peak that is greater than the intensity of an α″-Fe16N2 (202) peak by 0.19 in a diffraction pattern, where the diffraction vector is parallel to the alignment direction.

### Claim 9 (depends on 8)

The nanocomposite of claim 8, wherein the binder comprises a polymeric material.

### Claim 10 (depends on 9)

The nanocomposite of claim 9, wherein the polymeric material comprises an epoxy, an acrylic, an acrylate, a bismaleimide, an ester, a urethane, a styrene, a polyvinyl alcohol, a polyvinyl acetate, a cellulose acetate, an ethyl cellulose, a polycarbonate, a polyester, a syndiotactic polystyrene, or a combination thereof.

### Claim 11 (depends on 8)

The nanocomposite of claim 8, wherein the weight fraction of the nanoparticles relative to the nanocomposite is in the range of from 80% to 95%.

### Claim 12 (depends on 8)

The nanocomposite of claim 8, wherein the weight fraction of the nanoparticles relative to the nanocomposite is in the range of from 85% to 95%.

### Claim 13 (depends on 8)

The nanocomposite of claim 8, wherein the weight fraction of the nanoparticles relative to the nanocomposite is in the range of from 90% to 95%.

### Claim 14 (depends on 8)

The nanocomposite of claim 8, wherein the volume fraction of the nanoparticles relative to the nanocomposite is in the range of from 40% to 75%.

### Claim 15 (depends on 8)

The nanocomposite of claim 8, wherein the volume fraction of the nanoparticles relative to the nanocomposite is in the range of from 50% to 75%.

### Claim 16 (depends on 8)

The nanocomposite of claim 8, wherein the volume fraction of the nanoparticles relative to the nanocomposite is in the range of from 60% to 75%.

### Claim 17

A plurality of anisotropic iron nitride nanoparticles, the plurality of anisotropic iron nitride nanoparticles being characterized as having a saturation magnetization, MSat, >190 emu/g and coercivity, Hc, greater than 2,500 Oe;
wherein a ratio of integrated intensities of an α″-Fe16N2 (004) x-ray diffraction peak to an α″-Fe16N2 (202) x-ray diffraction peak is greater than 0.19.

### Claim 18 (depends on 17)

The plurality of anisotropic iron nitride nanoparticles of claim 17, wherein the plurality of anisotropic iron nitride nanoparticles are further characterized as having a uniform phase composition throughout, wherein the plurality of anisotropic iron nitride nanoparticles comprises a higher mass fraction of α″-Fe16N2 phase and a lower mass fraction of α-Fe and ε-Fe2-3N phases.

### Claim 19 (depends on 18)

The plurality of anisotropic iron nitride nanoparticles of claim 18, wherein the weight percent of the α″-Fe16N2 phase is at least 70%.

### Claim 20 (depends on 17)

The plurality of anisotropic iron nitride nanoparticles of claim 17, wherein the iron nitride nanoparticles are coated with one or more of carbon, boron, aluminum oxide, copper metal, or aluminum metal.

### Claim 21

A permanent magnet, comprising a plurality of iron nitride nanoparticles, the permanent magnet being characterized as having a saturation magnetization, MSat, in the range of from about 12.5 kG to about 14 kG, wherein a ratio of integrated intensities of an α″-Fe16N2 (004) x-ray diffraction peak to an α″-Fe16N2 (202) x-ray diffraction peak is greater than 0.19.

### Claim 22 (depends on 21)

The permanent magnet of claim 21, wherein the iron nitride nanoparticles are magnetically aligned and bonded in a matrix.

### Claim 23 (depends on 21)

The permanent magnet of claim 21, wherein the nanoparticles are further characterized as having a uniform phase composition throughout, wherein the nanoparticles comprises a higher mass fraction of α″-Fe16N2 phase and a lower mass fraction of α-Fe and ε-Fe2-3N phases.

### Claim 24 (depends on 23)

The permanent magnet of claim 23, wherein the weight percent of the α″-Fe16N2 phase is at least 70%.

### Claim 25 (depends on 21)

The permanent magnet of claim 21, wherein the iron nitride nanoparticles are coated with one or more of carbon, boron, aluminum oxide, copper metal, or aluminum metal.

### Claim 26 (depends on 21)

The permanent magnet of claim 21, wherein at least a portion of the iron nitride nanoparticles are characterized as being deagglomerated discrete primary particles.