# US 2019/0245129 A1 · Polycrystalline magnesium silicide and use thereof

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- Number: US 2019/0245129 A1
- Document ID: US20190245129A1
- Status: Published application
- Kind: A1
- Application number: 16/314,841
- Filed: 2017-07-05
- Published: 2019-08-08
- Earliest claimed: 2016-07-12
- Assignees: Tokyo University of Science Foundation
- Applicants: Tokyo University of Science Foundation
- Inventors: Tsutomu IIDA; Syunsuke KONDO; Mitsunobu NAKATANI
- Web page: https://patentgrep.com/patent/US20190245129A1

## CPC

- H10N 10/851: comprising inorganic compositions
- B22F 3/10: Sintering only
- C01B 33/06: Metal silicides (alloys C22)
- C04B 35/58: based on borides, nitrides, {i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides} or silicides {(containing free binder metal C22C29/00)}
- C22C 1/02: by melting {(C22C1/1036 takes precedence)}
- C22C 23/00: Alloys based on magnesium
- H10N 10/01: Manufacture or treatment
- H10N 10/10: operating with only the Peltier or Seebeck effects
- H10N 10/8556: {comprising compounds containing germanium or silicon}
- H10N 10/857: comprising compositions changing continuously or discontinuously inside the material
- B22F 2302/45: Others, including non-metals
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

Polycrystalline magnesium silicide containing only carbon as a dopant and having carbon distributed at the crystal grain boundaries and within the crystal grains, a thermoelectric conversion material obtained using the polycrystalline magnesium silicide, a sintered compact, a thermoelectric conversion element, and a thermoelectric conversion module, and methods for producing polycrystalline magnesium silicide and a sintered compact.

## Claims

### Claim 1

Unsintered polycrystalline magnesium silicide comprising only carbon as a dopant and having carbon distributed within crystal grains and at crystal grain boundaries.

### Claim 2 (depends on 1)

The polycrystalline magnesium silicide according to claim 1, wherein the polycrystalline magnesium silicide contains 0.05 at % to 3.0 at % of carbon.

### Claim 3 (depends on 1)

A thermoelectric conversion material comprising the polycrystalline magnesium silicide according to claim 1.

### Claim 4 (depends on 1)

A sintered body obtained by sintering the polycrystalline magnesium silicide according to claim 1, wherein a power factor at 523 K is 3.0×10−3 Wm−1K−2 or more, and a figure-of-merit parameter (Z) at 523 K is 0.78×10−3 K−1 or more.

### Claim 5

(canceled)

### Claim 6 (depends on 4)

The sintered body according to claim 4, wherein a dimensionless figure-of-merit parameter (ZT) at 523 K is 0.40 or more, and a dimensionless figure-of-merit parameter (ZT) at 873 K is 0.86 or more.

### Claim 7 (depends on 4)

A thermoelectric conversion element comprising a thermoelectric conversion part composed of the sintered body according to claim 4; and a first electrode and a second electrode provided to the thermoelectric conversion part.

### Claim 8 (depends on 7)

A thermoelectric conversion module comprising the thermoelectric conversion element according to claim 7.

### Claim 9 (depends on 1)

A method for producing the polycrystalline magnesium silicide according to claim 1, the method comprising heating and melting a starting material composition obtained by mixing magnesium, silicon, and a carbon source to produce a melted and solidified material.

### Claim 10 (depends on 9)

The method according to claim 9, wherein the carbon source is a carbon allotrope formed by carbon having a sp2 hybrid orbital and carbon having a sp3 hybrid orbital.

### Claim 11 (depends on 9)

The method according to claim 9, wherein the carbon source is fullerene.

### Claim 12 (depends on 9)

The method according to claim 9, further comprising pulverizing the melted and solidified material to produce a pulverized material.

### Claim 13

A method for producing a sintered body, the method comprising sintering a pulverized material obtained by the method according to claim