NANOPARTICLE COMPACT MATERIALS FOR THERMOELECTRIC APPLICATION

• US 20140318593A1
• Filed: 11/21/2012
• Published: 10/30/2014
• Est. Priority Date: 11/21/2011
• Status: Abandoned Application

• Current Assignee: Micross Advanced Interconnect Technology LLC
• Original Assignee: Research Triangle Institute, North Carolina State University (University of North Carolina System)
• Inventors: Venkatasubramanian, Rama, Stuart, Judy, Wiitala, Ryan, Thomas, Peter, Koch, Carl C., Chan, Tsungta Ethan
• Application Number:
  US14/359,817
• Publication Number:
  US 20140318593A1
• Time in Patent Office: Days
• US Class Current: 136/238
• CPC Class Codes: H10N 10/10 operating with only the Peltier or Seebeck effects
• CPC Class Codes: H10N 10/852 comprising tellurium, selenium or sulfur
• CPC Class Codes: H10N 10/853 comprising arsenic, antimony or bismuth H10N10/852 takes precedence
• CPC Class Codes: Y10T 428/268 Monolayer with structurally defined element

Abstract

A thermoelectric composite and a thermoelectric device and a method of making the thermoelectric composite. The thermoelectric composite is a semiconductor material formed from mechanically-alloyed powders of elemental constituents of the semiconductor material to produce nano-particles of the semiconductor material, and compacted to have at least a bifurcated grain structure. The bifurcated grain structure has at least two different grain sizes including small size grains in a range of 2-200 nm and large size grains in a range of 0.5 to 5 microns. The semiconductor material has a figure of merit ZT, defined as a ratio of the product of square of Seebeck coefficient, S², and electrical conductivity σ divided by the thermal conductivity k, which varies from greater than 1 at 300 K to 2.5 at temperatures of 300 to 500K.

Claims

1. A thermoelectric composite, comprising:

a semiconductor material formed from mechanically-alloyed powders of elemental constituents of the semiconductor material to produce nanoparticles of the semiconductor material, and compacted to have at least a bifurcated grain structure; and

said bifurcated grain structure having at least two different grain sizes including small size grains in a range of 2-200 nm and large size grains in a range of 0.5 to 5 microns.

2. The composite of claim 1, wherein the semiconductor material has a figure of merit ZT, defined as a ratio of the product of square of Seebeck coefficient S and electrical conductivity σ

divided by the thermal conductivity k, which varies from greater than 1 at 300 K to 2.5 at temperatures of 300 to 500K.

3. The composite of claim 1, wherein the semiconductor material comprises nano-size scattering sites including at least one of nano-voids, inclusions, precipitates, and grain boundaries.

4. The composite of claim 1, wherein the semiconductor material comprises nano-size scattering sites having dimensions less than 10 nm.

5. The composite of claim 1, wherein the semiconductor material comprises nano-size scattering sites having dimensions less than 5 nm.

13. The composite of claim 1, wherein the small size grains have a grain size ranging from 2 to 50 nm.

14. The composite of claim 1, wherein said compact comprises at least one of n-type Bi₂Te_3-xSe_x and p-type B_ySb_2-yTe₃.

15. The composite of claim 14, wherein x ranges from 0.1 to 0.9 and y ranges from 0.1 to 0.9.

16. The composite of claim 14, wherein x ranges from 0.2 to 0.5 and y ranges from 0.2 to 0.6.

17. The composite of claim 14, wherein x ranges from 0.25 to 0.35 and y ranges from 0.35 to 0.45.

20. The composite of claim 1, wherein said semiconductor material comprises n-type Bi₂Te_3-xSe_x and has at least one of the following properties:

a logarithmic slope of resistivity ranging from 1.09 to 1.25/°

C.;

a Seebeck coefficient at 125°

C. ranging from 225 to 325 μ

v/K;

a thermal conductivity at 125°

C. ranging from 1.1 to 1.6 W/m-K; and

a power factor at 125°

C. ranging from 45 to 100 micro W/cm-K.

46. The composite of claim 1, wherein said semiconductor material comprises p-type Bi_ySb_2-yTe₃ and has at least one of the following properties:

a logarithmic slope of resistivity ranging from 1.75 to 2.27/°

C.;

a Seebeck coefficient at 125°

C. ranging from 250 to 325 μ

\7K;

a thermal conductivity at 125°

C. ranging from 1.0 to 1.35 W/m-K; and

a power factor at 125°

C. ranging from 40 to 100 micro W/cm-K².

6-12. -12. (canceled)

18-19. -19. (canceled)

21-45. -45. (canceled)

47. A thermoelectric device, comprising:

an n-type compacted thermoelectric element having at least a bifurcated grain structure with at least two different grain sizes including small size grains in a range of 2-200 nm and large size grains in a range of 0.5 to 5 microns; and

a p-type compacted thermoelectric element having at least a bifurcated grain structure with at least two different grain sizes including small size grains in a range of 2-200 nm and large size grains in a range of 0.5 to 5 microns.

48. The device of claim 47, wherein:

the n-type compacted thermoelectric element comprises a n-type Bi₂Te_3-xSe_x section having grains consolidated from nanoparticles of Bi₂Te_3-xSe_x; and

the p-type compacted thermoelectric element comprises a p-type Bi_ySb_2-yTe₃ section having grains consolidated from nanoparticles of p-type Bi_ySb_2-yTe₃.

49. The device of claim 47, wherein said grain size of the n-type Bi₂Te_3-xSe_x section or the p-type Bi_ySb_2-yTe₃ section ranges from 30 to 50 nm.

50. The device of claim 47, wherein said grain size of the n-type Bi₂Te_3-xSe_x section or the p-type Bi_ySb_2-xTe₃ section averages 40 nm.

51. A compacted composite, comprising:

a material formed from mechanically-alloyed powders of elemental constituents of the semiconductor material to produce nanoparticles of the semiconductor material, and compacted to have at least a bifurcated grain structure; and

said bifurcated grain structure having at least two different grain sizes including small size grains in a range of 2-200 nm and large size grains in a range of 0.5 to 5 microns.