# US 2013/0278104 A1 · Rare Earth Magnet and Motor Using the Same

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- Number: US 2013/0278104 A1
- Document ID: US20130278104A1
- Status: Published application
- Kind: A1
- Application number: 13/924,746
- Filed: 2013-06-24
- Published: 2013-10-24
- Earliest claimed: 2009-05-12
- Assignees: Hitachi, Ltd.
- Applicants: Hitachi, Ltd.
- Inventors: Matahiro KOMURO; Yuichi SATSU; Hiroyuki SUZUKI
- Web page: https://patentgrep.com/patent/US20130278104A1

## CPC

- H01F 1/408: {half-metallic, i.e. having only one electronic spin direction at the Fermi level, e.g. CrO2, Heusler alloys (H01F10/1936 takes precedence)}
- H01F 1/0556: {pressed}
- H01F 1/0557: {sintered}
- H01F 1/0577: {sintered}
- H01F 1/058: and IVa elements, e.g. Gd2Fe14C
- H01F 1/0596: {of rhombic or rhombohedral Th2Zn17 structure or hexagonal Th2Ni17 structure}
- H01F 1/08: pressed, sintered, or bound together
- H01F 1/086: {sintered}
- H01F 41/0293: {diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets}
- H02K 1/02: characterised by the magnetic material
- H02K 1/27: Rotor cores with permanent magnets
- C22C 2202/02: Magnetic
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

The present invention makes it possible to increase the residual magnetic flux density and the coercive force of a rare earth magnet; and raise the Curie temperature. In a magnet formed by compressing magnetic particles, the surface of a magnetic particle is covered with a metal fluoride film, the magnetic particle has a crystal structure containing a homo portion formed by bonding adjacent iron atoms and a hetero portion formed by bonding two iron atoms via an atom other than iron, and the distance between the two iron atoms in the hetero portion is different from the distance between the adjacent iron atoms in the homo portion.

## Claims

### Claim 1

A magnet formed by compressing magnetic particles, wherein:
a surface of the magnetic particles is covered with a metal fluoride film;
the magnetic particles have a crystal structure containing a homo portion formed by bonding adjacent iron atoms and a hetero portion formed by bonding two iron atoms via an atom other than iron;
a distance between the two iron atoms in the hetero portion is different from a distance between the adjacent iron atoms in the homo portion; and
the magnet has a structure formed by touching a mother phase constituting a center portion of the magnetic particles directly to a crystal containing the hetero portion.

### Claim 2 (depends on 1)

A magnet according to claim 1, wherein the hetero portion contains an element selected from the group consisting of fluorine, boron, carbon, nitrogen and oxygen.

### Claim 3 (depends on 1)

A magnet according to claim 1, wherein the magnetic particles contain a rare earth element.

### Claim 4 (depends on 1)

A magnet according to claim 1, wherein the metal fluoride film contains a fluoride of an element selected from the group consisting of rare earth elements, alkali metal elements and alkali earth metal elements.

### Claim 5 (depends on 1)

A magnet according to claim 1, wherein a concentration of the atom other than iron contained in the mother phase is higher at an outer circumferential portion of the mother phase than at a center portion of the mother phase.

### Claim 6 (depends on 1)

A rotor comprising a magnet according to claim 1.

### Claim 7 (depends on 6)

A rotor according to claim 6, wherein a concentration of the atom other than iron at an outer circumferential portion of the magnet is higher than that of the atom other than iron at an inner circumferential portion of the magnet.

### Claim 8 (depends on 6)

A rotor according to claim 6, wherein a magnetic flux density at the outer circumferential portion of the magnet is higher than that at the inner circumferential portion of the magnet.

### Claim 9 (depends on 6)

A rotor according to claim 6, wherein a magnetic flux density and a coercive force at the outer circumferential portion of the magnet are higher than those at the inner circumferential portion of the magnet.

### Claim 10 (depends on 1)

A motor comprising a magnet according to claim 1.

### Claim 11 (depends on 6)

A motor comprising a rotor according to claim 6.

### Claim 12 (depends on 1)

A rotary electrical apparatus comprising a magnet according to claim 1.