Thermoelectric semiconductor compound and method of making the same

• US 6,225,548 B1
• Filed: 11/29/1999
• Issued: 05/01/2001
• Est. Priority Date: 11/27/1998
• Status: Expired due to Fees

• Current Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Original Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Inventors: Sakakibara, Tsutomu, Takigawa, Yasuo, Imoto, Takanori
• Primary Examiner(s): Gorgos, Kathryn
• Assistant Examiner(s): Parsons, Thomas H
• Application Number:
  US09/447,951
• Time in Patent Office: 519 Days
• Field of Search: 136/201, 136/203, 136/205, 136/236.1, 136/238, 136/240, 136/241
• US Class Current: 136/201
• CPC Class Codes: H10N 10/852 comprising tellurium, selenium or sulfur

Abstract

A thermoelectric semiconductor compound is provided whose performance index Z is remarkably improved without sacrificing Seebeck coefficient, electrical conductivity or thermal conductivity. The thermoelectric semiconductor compound includes a first thermoelectric semiconductor which is in the form of matrix and a second thermoelectric semiconductor which is in the form of particles dispersed in the matrix. The first thermoelectric semiconductor and the second thermoelectric semiconductor have a common element. The average diameter D of the dispersed particles complies with a formula of A<D<B, where A is the mean free path of a carrier in a single crystal of the second thermoelectric semiconductor and B is the mean free path of a long wave length phonon in the single crystal of the second thermoelectric semiconductor. A method for making the a thermoelectric semiconductor compound is provided.

Claims

1. A thermoelectric semiconductor compound comprising:

a matrix comprising a first thermoelectric semiconductor; and

particles of a second thermoelectric semiconductor dispersed in the matrix, wherein

the first thermoelectric semiconductor and the second thermoelectric semiconductor include a common element; and

A<

D<

B, where

A is a mean free path of a carrier in a single crystal of the second thermoelectric semiconductor,

D is an average diameter of the particles of the second thermoelectric semiconductor, and

B is a mean free path of a long wavelength phonon in the single crystal of the second thermoelectric semiconductor.

2. The thermoelectric semiconductor compound according to claim 1, wherein D is in a range from 0.1 μ

m to 150 μ

m inclusive.

3. The thermoelectric semiconductor compound according to claim 1, wherein the common element is Te.

4. The thermoelectric semiconductor compound according to claim 3, wherein the first thermoelectric semiconductor comprises AgBiTe₂, and the second thermoelectric semiconductor comprises Ag₂Te.

5. The thermoelectric semiconductor compound according to claim 3, wherein the first thermoelectric semiconductor is a member of a BiTe₃ family of semiconductors.

6. The thermoelectric semiconductor compound according to claim 1, wherein a Seebeck coefficient of the first thermoelectric semiconductor is larger than a Seebeck coefficient of the second thermoelectric semiconductor.

14. A method of using a thermoelectric semiconductor compound, the method comprising passing an electric current through the thermoelectric semiconductor compound of claim 1.

15. A method of using a thermoelectric semiconductor compound, the method comprising creating a temperature difference between opposing sides of the thermoelectric semiconductor compound of claim 1.

7. A method for making a thermoelectric semiconductor compound, the method comprising:

mixing a raw material of a first thermoelectric semiconductor and a raw material of a second thermoelectric semiconductor to form a mixture, where

the raw material of the first thermoelectric semiconductor and the raw material of the second thermoelectric semiconductor both include a common element,

the first thermoelectric semiconductor melts at a first melting point,

the second thermoelectric semiconductor melts at a second melting point, and

the second melting point is higher than the first melting point;

melting the mixture at a temperature greater than the second melting point to form a melted mixture;

cooling the melted mixture to a temperature lower than the second melting point and higher than the first melting point to form a melted mixture containing crystallized particles of the second thermoelectric semiconductor; and

cooling the melted mixture containing crystallized particles of the second thermoelectric semiconductor to a temperature lower than the first melting point to form a solid of the thermoelectric semiconductor compound.

8. The method according to claim 7, wherein A<

E<

B, where

A is a mean free path of a carrier in a single crystal of the second thermoelectric semiconductor;

E is an average diameter of the crystallized particles of the second thermoelectric semiconductor; and

B is a mean free path of a long wavelength phonon in the single crystal of the second thermoelectric semiconductor.

9. The method according to claim 8, wherein E is in a range from 0.1 μ

m to 150 μ

m inclusive.

10. The method according to claim 7, wherein the common element is Te.

11. The method according to claim 10, wherein the first thermoelectric semiconductor comprises AgBiTe₂, and the second thermoelectric semiconductor comprises Ag₂Te.

12. The method according to claim 10, wherein the first thermoelectric semiconductor is a member of a BiTe₃ family of semiconductors.

13. The method according to claim 7, wherein a Seebeck coefficient of the first thermoelectric semiconductor is larger than a Seebeck coefficient of the second thermoelectric semiconductor.