Anisotropically elongated thermoelectric material, process for preparing the same, and device comprising the material

1. An anisotropically elongated thermoelectric nanocomposite comprising:

a plurality of thermoelectric material layers and a plurality of insulating material layers; where the anisotropically elongated thermoelectric nanocomposite has a uniaxially deformed structure; and wherein the plurality of insulating material layers and the plurality of thermoelectric material layers are alternating concentric layers sharing a common central axis.

2. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the insulating material comprises one of nanoporous oxide, nitride and fluoride aligned along the elongation direction of the thermoelectric nanocomposite.

3. The anisotropically elongated thermoelectric nanocomposite of claim 2 , wherein the nanoporous oxide is at least one selected from a group consisting of SiO 2 , Al 2 O 3 , and oxides of Ti, Zr, Hf, Nb, Ta and their alloys.

4. The anisotropically elongated thermoelectric nanocomposite of claim 3 , wherein the nanoporous oxide including SiO 2 is fabricated by controlled oxidation of porous Si into porous silica SiO 2 .

5. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the insulating material forms a nanopore array, and the nanopore array is created by guided anodization with nucleation of anodized pores dictated by nano-indentation.

6. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the insulating material forms a nanopore array, and the nanopore array is created by guided anodization with nucleation of anodized pores dictated by nano-mask patterning using at least one of a nano-imprinted resist and a thermally two-phase decomposed diblock copolymer layer.

7. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the anisotropically elongated thermoelectric nanocomposite has average diameter of equal to or less than about 20 nm.

8. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the anisotropically elongated thermoelectric material has average diameter of equal to or less than about 10 nm.

9. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the thermoelectric nanocomposite has ZT value of at least about 1.5.

10. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the thermoelectric material comprises at least one nanowire structure, and an average aspect ratio of a length thereof to a diameter thereof is at least about 2.

11. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the thermoelectric material comprises at least one nanowire structure, and an average aspect ratio of a length thereof to a diameter thereof is at least about 5.

12. Anisotropically elongated, concentrically superlatticed thermoelectric nanocomposite comprising:

a plurality of multi-layered nanowire structures embedded in a nanoporous insulating matrix or in a nonporous insulating matrix,

wherein each of the plurality of multi-layered nanowire structures comprises:

a multi-layered cylindrical thermoelectric material; and

an insulating layer deposited between layers of the multi-layered cylindrical thermoelectric material; wherein the thermoelectric nanocomposite has a uniaxially deformed structure; and wherein the insulating layer and the layers of the multi-layered cylindrical thermoelectric material are concentric and share a common central axis.

13. The anisotropically elongated, concentrically superlatticed thermoelectric nanocomposite of claim 12 , wherein each of the plurality of multi-layered nanowire structures include at least 3 layers of the multi-layered cylindrical thermoelectric material.

14. The anisotropically elongated, concentrically superlatticed thermoelectric nanocomposite of claim 12 , wherein each layer of the multi-layered cylindrical thermoelectric material and the insulating layer has an average thickness of about 0.5 nm to about 2 nm.

15. The anisotropically elongated, concentrically superlatticed thermoelectric nanocomposite of claim 12 , wherein the insulating layer is at least one selected from the group consisting of SiO 2 , Al 2 O 3 , or oxides of Ca, Mg, Cr, Ti, Zr, Hf, Nb, Ta, rare earth metals or their alloys, nitrides or fluorides of Si, Al, Ca, Mg, Cr, Ti, Zr, Hf, Nb, Ta, and rare earth metals or alloys thereof.

16. The anisotropically elongated, concentrically superlatticed thermoelectric nanocomposite of claim 12 , wherein the multi-layered nanowire structures are formed by alternating deposition of a thermoelectric material layer and the insulating layer using at least one of chemical vapor deposition, sputtering and an atomic layer deposition technique.

17. The anisotropically elongated, concentrically superlatticed thermoelectric nanocomposite of claim 12 , wherein each layer of the multi-layered cylindrical thermoelectric material is obtained by introducing nanoparticle precipitation within each layer of the multi-layered cylindrical thermoelectric material using at least one of off-stoichiometric composition and by co-depositing an oxide-dispersoid-forming element during deposition of a concentric superlattice layer.

18. A uniaxially deformed thermoelectric nanocomposite comprising: a thermoelectric material embedded in an electrically and thermally insulating material; wherein where the thermoelectric nanocomposite has a uniaxially deformed structure; and

wherein the thermoelectric material is at least one selected from a group consisting of Si, Si1−xGex (wherein 0<x<1), Sb2Te3, BixSb2−xTe3 (wherein 0<x<2), Bi2TexSe3−x (wherein 0<x<3), B4C/B9C, BiSb alloys, Mg—Si, Mg—Ge, Mg—Sn or their ternary systems, binary, tertiary or quaternary skutterudites, and lead-antimony-silver-tellurium (Pb—Sb—Ag—Te) thermoelectric alloys; wherein a plurality of the insulating material layers and a plurality of the thermoelectric material layers alternate with each other and are arranged concentrically such that they share a common central axis.

19. The uniaxially deformed thermoelectric nanocomposite of claim 18 , wherein the thermoelectric material has an anisotropically elongated and nanofibered structure.

20. The uniaxially deformed thermoelectric nanocomposite of claim 18 , wherein the thermoelectric material has a nanowire structure, and the average aspect ratio of length to diameter thereof is at least about 2.

21. The uniaxially deformed thermoelectric nanocomposite of claim 18 , wherein the thermoelectric material has a nanowire structure, and the average aspect ratio of length to diameter thereof is at least about 5.

22. The uniaxially deformed, anisotropically elongated nanofibered thermoelectric nanocomposite of claim 18 , wherein the electrically and thermally insulating material is at least one selected from the group consisting of oxides, nitrides or fluorides of SiO 2 or Al 2 O 3 , oxides of Ca, Mg, Cr, Ti, Zr, Hf, Nb, Ta, rare earth metals, and alloys of rare earth metals, and nitrides or fluorides of Si, Al, Ca, Mg, Cr, Ti, Zr, Hf, Nb, Ta, rare earth metals and alloys thereof.

23. The uniaxially deformed thermoelectric nanocomposite of claim 18 , wherein the thermoelectric material is about 30% to about 90% of the volume of the thermoelectric nanocomposite, with the remaining portion being the electrically and thermally insulating material.

24. The uniaxially deformed thermoelectric nanocomposite of claim 18 , wherein the thermoelectric material has phonon scattering defects, wherein the phonon scattering defects include a phonon-scattering surface roughness which increases a surface area of the thermoelectric material by at least about 20%, or wherein the phonon-scattering defects include phonon-scattering incorporated insulator particles which comprise at least 1% of the volume of the thermoelectric material, or wherein the phonon-scattering defects include phonon scattering grain boundaries with an average grain size of less than about 200 nm.

25. The uniaxially deformed thermoelectric nanocomposite of claim 18 , wherein the thermoelectric material has an anisotropically elongated geometry according to a thermoelectric phase thereof and an average diameter of the uniaxially deformed thermoelectric nanocomposite is in a range of about 1 nm to about 100 nm.

26. The uniaxially deformed thermoelectric nanocomposite of claim 18 , wherein a microstructure of the thermoelectric material has an increased surface area according to a thermoelectric phase thereof with a phonon-scattering surface roughness increase of at least 20% larger surface area relative to a non-phonon-scattering surface thereof.

27. The uniaxially deformed thermoelectric nanocomposite of claim 18 , wherein a microstructure of the thermoelectric material has an increased number of pushed-in phonon-scattering foreign nanoparticles incorporated within the thermoelectric phase thereof, with the phonon-scattering foreign nanoparticles being at least about 1% of the thermoelectric material by volume.

28. A thermoelectric device, comprising:

a first electrode;

a second electrode; and

a thermoelectric element disposed between the first electrode and the second electrode,

wherein the thermoelectric element comprises an anisotropically elongated thermoelectric nanocomposite according to claim 1 .

29. An thermoelectric apparatus, comprising:

a heat source; and

a thermoelectric device including:

a first electrode which absorbs heat from the heat source;

a second electrode disposed substantially opposite the first electrode; and

a thermoelectric element disposed between the first electrode and the second electrode,

wherein the thermoelectric element comprises an anisotropically elongated thermoelectric nanocomposite according to claim 1 .

30. The anisotropically elongated thermoelectric nanocomposite of claim 1 , wherein the thermoelectric material is at least one selected from a group consisting of Si, Si 1−x Ge x (wherein 0<x<1), Bi 2 Te 3 , Sb 2 Te 3 , Bi x Sb 2−x Te 3 (wherein 0<x<2), Bi 2 Te x Se 3−x (wherein 0<x<3), B 4 C/B 9 C, BiSb alloys, PbTe, Mg—Si, Mg—Ge, Mg—Sn or their ternary systems, binary, tertiary or quaternary skutterudites, and lead-antimony-silver-tellurium (Pb—Sb—Ag—Te) thermoelectric alloys.

31. The anisotropically elongated, concentrically superlatticed thermoelectric nanocomposite of claim 12 , wherein the thermoelectric material is at least one selected from a group consisting of Si, Si 1−x Ge x (wherein 0<x<1), Bi 2 Te 3 , Sb 2 Te 3 , Bi x Sb 2−x Te 3 (wherein 0<x<2), Bi 2 Te x Se 3−x (wherein 0<x<3), B 4 C/B 9 C, BiSb alloys, PbTe, Mg—Si, Mg—Ge, Mg—Sn or their ternary systems, binary, tertiary or quaternary skutterudites, and lead-antimony-silver-tellurium (Pb—Sb—Ag—Te) thermoelectric alloys.

32. Anisotropically elongated, concentrically superlatticed thermoelectric nanocomposite comprising:

a plurality of multi-layered nanowire structures embedded in a nanoporous insulating matrix or in a nonporous insulating matrix,

wherein each of the plurality of multi-layered nanowire structures comprises:

a plurality of thermoelectric material layers and a plurality of insulating material layers; where the anisotropically elongated thermoelectric nanocomposite has a uniaxially deformed structure; and wherein the plurality of insulating material layers and the plurality of thermoelectric material layers are alternating concentric layers sharing a common central axis.

33. The anisotropically elongated thermoelectric nanocomposite of claim 32 , wherein an amount of the one of the nanoporous insulating matrix and the non insulating matrix is less than about 60% of a volume of the anisotropically elongated thermoelectric nanocomposite.

34. The anisotropically elongated thermoelectric nanocomposite of claim 32 , wherein an amount of the nanoporous insulating matrix is less than about 30% of a volume of the anisotropically elongated thermoelectric nanocomposite.