US5610366A
Expired / Lapsed
US
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High performance thermoelectric materials and methods of preparation
Assignee: California Institute of Technology
•
Filing: 1994-01-28
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Granted: 1997-03-11
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Expires: 2014-01-28
Abstract
Abstract Transition metals (T) of Group VIII (Co, Rh and Ir) have been prepared as semiconductor alloys with Sb having the general formula TSb3. The skutterudite-type crystal lattice structure of these semiconductor alloys and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor alloys having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using vertical gradient freeze techniques, liquid-solid phase sintering techniques, low temperature powder sintering and/or hot-pressing. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities (up to 8000 cm2.V-1.s-1), good Seebeck coefficients (up to 400 mu VK-1 between 300 DEG C. and 700 DEG C.), and low thermal conductivities (as low as 15 mW/cmK). Optimizing the transport properties of semiconductor materials prepared from elemental mixtures Co, Rh, Ir and Sb resulted in a two fold increase in the thermoelectric figure of merit (ZT) at temperatures as high as 400 DEG C. for thermoelectric elements fabricated from such semiconductor materials.
Inventors
- 👤 Jean-Pierre Fleurial
- 👤 Thierry F. Caillat
- 👤 Alexander Borshchevsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 12:16
CPC Classifications
H; H10; H10N; H10N10/00; H10N10/80; H10N10/85; H10N10/851; H10N10/853; H10N10/10; H10N10/17; Y; Y10; Y10S; Y10S257/00; Y10S257/93
Claims Analysis
Total Claims: 54
Claim 1
Independent Claim
49 words
A thermoelectric device having a plurality of thermoelectric elements with at least one of the thermoelectric elements comprising a first material having a skutterudite-type crystal lattice structure with a unit cell of eight groups of AB 3 wherein A comprises a metal atom and B comprises a non-metal atom.
Claim 2
Dependent Claim
49 words
A thermoelectric device having a plurality of thermoelectric elements with at least one of the thermoelectric elements comprising a first material having a skutterudite-type crystal lattice structure with a unit cell of eight groups of AB 3 wherein A comprises a metal atom and B comprises a non-metal atom.
Claim 3
Dependent Claim
17 words
The thermoelectric device as defined in claim 1 wherein the first material further comprises IrSb 3 .
Claim 4
Dependent Claim
17 words
The thermoelectric device as defined in claim 1 wherein the first material further comprises CoSb 3 .
Claim 5
Dependent Claim
17 words
The thermoelectric device as defined in claim 1 wherein the first material further comprises RhSb 3 .
Claim 6
Dependent Claim
28 words
The thermoelectric device as defined in claim 1 wherein the first material further comprises a semiconductor alloy having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 7
Dependent Claim
70 words
A thermoelectric device comprising: a first material having a skutterudite-type crystal lattice structure with a unit cell of eight groups of AB 3 wherein A comprises a metal atom and B comprises a non-metal atom; and a second material selected from the group consisting of Bi-Sb alloys, Bi 2 Te 3 based alloys, PbTe based alloys, β-FeSi 2 based alloys, Ga 1-x In x Sb based alloys, and SiGe alloys.
Claim 8
Dependent Claim
70 words
A thermoelectric device comprising: a first material having a skutterudite-type crystal lattice structure with a unit cell of eight groups of AB 3 wherein A comprises a metal atom and B comprises a non-metal atom; and a second material selected from the group consisting of Bi-Sb alloys, Bi 2 Te 3 based alloys, PbTe based alloys, β-FeSi 2 based alloys, Ga 1-x In x Sb based alloys, and SiGe alloys.
Claim 9
Dependent Claim
32 words
A thermoelectric device having a plurality of thermoelectric elements with at least one of the thermoelectric elements comprising a first material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 10
Dependent Claim
32 words
A thermoelectric device having a plurality of thermoelectric elements with at least one of the thermoelectric elements comprising a first material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 11
Dependent Claim
19 words
The thermoelectric device as defined in claim 7 wherein the first material further comprises a skutterudite-type crystal lattice structure.
Claim 12
Dependent Claim
53 words
A thermoelectric device comprising: a first material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1; and a second material selected from the group consisting of Bi-Sb alloys, Bi 2 Te 3 based alloys, PbTe based alloys, β-FeSi 2 based alloys, Ga 1-x In x Sb based alloys, and SiGe alloys.
Claim 13
Dependent Claim
53 words
A thermoelectric device comprising: a first material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1; and a second material selected from the group consisting of Bi-Sb alloys, Bi 2 Te 3 based alloys, PbTe based alloys, β-FeSi 2 based alloys, Ga 1-x In x Sb based alloys, and SiGe alloys.
Claim 14
Dependent Claim
53 words
A thermoelectric device having a plurality of thermoelectric elements formed from at least two different types of semiconductor materials comprising: a portion of the thermoelectric elements formed from P-type semiconductor material having a skutterudite-type crystal lattice structure; and the P-type semiconductor material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 15
Dependent Claim
53 words
A thermoelectric device having a plurality of thermoelectric elements formed from at least two different types of semiconductor materials comprising: a portion of the thermoelectric elements formed from P-type semiconductor material having a skutterudite-type crystal lattice structure; and the P-type semiconductor material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 16
Dependent Claim
52 words
The thermoelectric device as defined in claim 10 further comprising another portion of the thermoelectric elements formed from N-type semiconductor material selected from the group consisting of Bi-Sb alloys, Bi 2 Te 3 based alloys, PbTe based alloys, β-FeSi 2 based alloys, Ga 1-x In x Sb based alloys, and SiGe alloys.
Claim 17
Dependent Claim
133 words
Apparatus using gradient freeze techniques to prepare a semiconductor alloy for use in fabricating thermoelectric elements comprising: a furnace defined in part by a housing having a chamber with a first heater and a second heater disposed therein; the first heater disposed within the chamber above the second heater; a thermal baffle disposed within the chamber between the first heater and the second heater; a container disposed within the chamber with the container adjacent to the thermal baffle; a plurality of elemental materials disposed within the container for melting within the furnace to form the desired semiconductor alloys; a sealed vessel with a first elemental material and a second elemental material; and the first elemental material selected from the group consisting of iridium, rhodium and cobalt, and the second elemental material comprising antimony.
Claim 18
Dependent Claim
133 words
Apparatus using gradient freeze techniques to prepare a semiconductor alloy for use in fabricating thermoelectric elements comprising: a furnace defined in part by a housing having a chamber with a first heater and a second heater disposed therein; the first heater disposed within the chamber above the second heater; a thermal baffle disposed within the chamber between the first heater and the second heater; a container disposed within the chamber with the container adjacent to the thermal baffle; a plurality of elemental materials disposed within the container for melting within the furnace to form the desired semiconductor alloys; a sealed vessel with a first elemental material and a second elemental material; and the first elemental material selected from the group consisting of iridium, rhodium and cobalt, and the second elemental material comprising antimony.
Claim 19
Dependent Claim
28 words
The apparatus as defined in claim 12, further comprising an antimony rich melt with a composition between 90% and 99.5% antimony as compared to the first elemental material.
Claim 20
Dependent Claim
61 words
The apparatus as defined in claim 12 further comprising the first heater, the second heater, and the thermal baffle cooperating to form a sharp temperature gradient within the container for forming a single crystal of semiconductor alloy selected from the group consisting of CoSb 3 , RhSb 3 and Co 1-x-y Rh x Ir y Sb 3 wherein 0≦x≦1 and 0≦y≦1.
Claim 21
Dependent Claim
79 words
Apparatus using liquid-solid phase sintering techniques to prepare a semiconductor alloy for use in fabricating thermoelectric elements comprising: an isothermal furnace defined in part by a housing having a chamber with a heater disposed therein; a container disposed within the chamber, with the container spaced intermediate from the interior surfaces of the chamber; and a stoichiometric mixture of elemental materials selected from the group consisting of Co, Rh, Ir and Sb disposed within the container for forming polycrystalline ingots.
Claim 22
Dependent Claim
79 words
Apparatus using liquid-solid phase sintering techniques to prepare a semiconductor alloy for use in fabricating thermoelectric elements comprising: an isothermal furnace defined in part by a housing having a chamber with a heater disposed therein; a container disposed within the chamber, with the container spaced intermediate from the interior surfaces of the chamber; and a stoichiometric mixture of elemental materials selected from the group consisting of Co, Rh, Ir and Sb disposed within the container for forming polycrystalline ingots.
Claim 23
Dependent Claim
49 words
The apparatus as defined in claim 15 further comprising: the container sealed with a vacuum formed therein; a rod vertically disposed within the chamber and the container secured to one end of the rod; and the lower portion of the container tapered towards the one end of the rod.
Claim 24
Dependent Claim
39 words
The apparatus as defined in claim 15 further comprising: a layer of iridium powder disposed within the lower portion of the container adjacent to the rod; and a layer of antimony disposed within the container above the iridium powder.
Claim 25
Dependent Claim
77 words
The apparatus as defined in claim 15 wherein the container further comprises: a sealed vessel with a first elemental material layer and a second elemental material layer; the first elemental material layer disposed within the lower portion of the sealed vessel, and the second elemental material layer disposed above the first material layer; and the first elemental material layer selected from the group consisting of iridium, rhodium and cobalt, and the second elemental material layer comprising antimony.
Claim 26
Dependent Claim
27 words
The apparatus as defined in claim 15 wherein the stoichiometric mixture further comprises one layer of material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y wherein 0≦x≦1 and 0≦y≦1.
Claim 27
Independent Claim
112 words
A method of preparing a semiconductor alloy having a skutterudite-type crystal lattice structure for use in fabricating thermoelectric elements comprising the steps of: placing a first material selected from the group consisting of Ir, Rh and Co, and a second material comprising antimony in a container; placing the container within a furnace with the second material vertically disposed above the first material; heating the furnace to a preselected temperature to allow liquid-solid phase sintering of the first material and the second material; and retaining the container within the furnace for a preselected length of time to allow formation of polycrystalline ingots of the semiconductor alloy having the desired skutterudite-type crystal lattice structure.
Claim 28
Independent Claim
112 words
A method of preparing a semiconductor alloy having a skutterudite-type crystal lattice structure for use in fabricating thermoelectric elements comprising the steps of: placing a first material selected from the group consisting of Ir, Rh and Co, and a second material comprising antimony in a container; placing the container within a furnace with the second material vertically disposed above the first material; heating the furnace to a preselected temperature to allow liquid-solid phase sintering of the first material and the second material; and retaining the container within the furnace for a preselected length of time to allow formation of polycrystalline ingots of the semiconductor alloy having the desired skutterudite-type crystal lattice structure.
Claim 29
Dependent Claim
47 words
The method of preparing a semiconductor alloy as defined in claim 20, further comprising the steps of forming an elemental mixture having the general formula (TSb 3 ) wherein T is provided by the first material and the elemental mixture is within ±2 atomic % of stoichiometry.
Claim 30
Dependent Claim
51 words
The method of preparing a semiconductor alloy as defined in claim 20, further comprising the steps of: forming a vacuum in the container after the first and second layers of material have been placed therein; and sealing the container to trap the vacuum with the first and second material disposed therein.
Claim 31
Dependent Claim
39 words
The method of preparing a semiconductor alloy as defined in claim 22 further comprising the step of forming the first material from a mixture of Ir, Co and Rh with the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y wherein 0≦x≦1 and 0≦y≦1.
Claim 32
Dependent Claim
40 words
The method of preparing a semiconductor alloy as defined in claim 20 further comprising the steps of: heating the furnace to a temperature of at least 650° C.; and retaining the container in the furnace for at least fifteen minutes.
Claim 33
Dependent Claim
40 words
The method of preparing a semiconductor alloy as defined in claim 20 further comprising the step of vibrating a rod attached to the container for stirring the materials disposed within the container during growth of the skutterudite-type crystal lattice structure.
Claim 34
Independent Claim
126 words
A method of preparing a semiconductor alloy having a skutterudite-type crystal lattice structure for use in fabricating thermoelectric elements comprising the steps of: placing a first material selected from the group consisting of Ir, Rh and Co, and a second material comprising antimony in a container; placing the container with the first material and second material vertically disposed within a furnace having two heaters; heating the furnace to establish a preselected temperature gradient to melt the first and second materials to form a liquid and to grow a semiconductor crystal from the liquid by gradient freeze techniques; and retaining the container within the furnace for a preselected length of time to allow growing the crystal of the semiconductor alloy having the desired skutterudite-type crystal lattice structure.
Claim 35
Independent Claim
126 words
A method of preparing a semiconductor alloy having a skutterudite-type crystal lattice structure for use in fabricating thermoelectric elements comprising the steps of: placing a first material selected from the group consisting of Ir, Rh and Co, and a second material comprising antimony in a container; placing the container with the first material and second material vertically disposed within a furnace having two heaters; heating the furnace to establish a preselected temperature gradient to melt the first and second materials to form a liquid and to grow a semiconductor crystal from the liquid by gradient freeze techniques; and retaining the container within the furnace for a preselected length of time to allow growing the crystal of the semiconductor alloy having the desired skutterudite-type crystal lattice structure.
Claim 36
Dependent Claim
38 words
The method of preparing a semiconductor alloy as defined in claim 26, further comprising the steps of forming the first material from cobalt powder and the second material from antimony powder with an atomic ratio rich in antimony.
Claim 37
Dependent Claim
49 words
The method of preparing a semiconductor alloy as defined in claim 27, further comprising the steps of: forming a vacuum in the container after the first and second materials have been placed therein; and sealing the container to trap the vacuum with the first and second material disposed therein.
Claim 38
Dependent Claim
39 words
The method of preparing a semiconductor alloy as defined in claim 26 further comprising the step of forming the first material from a mixture of Ir, Co and Rh with the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y wherein 0≦x≦1 and 0≦y≦1.
Claim 39
Dependent Claim
31 words
The method of preparing a semiconductor alloy as defined in claim 26 further comprising the step of attaching one end of the container with a rod vertically disposed in the furnace.
Claim 40
Independent Claim
84 words
A method of preparing a semiconductor alloy for use in fabricating thermoelectric elements from an approximately stoichiometric mixture comprising the steps of: placing elemental powders selected from the group consisting of Ir, Rh, Co and Sb in a container to form the mixture; placing the container with the mixture within an isothermal furnace; and retaining the container and the mixture within the isothermal furnace for a preselected length of time to allow formation of the semiconductor alloyed powders having a skutterudite-type crystal lattice structure.
Claim 41
Independent Claim
84 words
A method of preparing a semiconductor alloy for use in fabricating thermoelectric elements from an approximately stoichiometric mixture comprising the steps of: placing elemental powders selected from the group consisting of Ir, Rh, Co and Sb in a container to form the mixture; placing the container with the mixture within an isothermal furnace; and retaining the container and the mixture within the isothermal furnace for a preselected length of time to allow formation of the semiconductor alloyed powders having a skutterudite-type crystal lattice structure.
Claim 42
Dependent Claim
26 words
The method of preparing a semiconductor alloy as defined in claim 31, further comprising the steps of placing the alloyed powders in a graphite die container.
Claim 43
Dependent Claim
42 words
The method of preparing a semiconductor alloy as defined in claim 31, further comprising the step of retaining the container in the isothermal furnace for at least 30 minutes at a temperature not higher than 630° C. to form the alloyed powders.
Claim 44
Dependent Claim
58 words
The method of preparing a semiconductor alloy as defined in claim 33 further comprising to steps of: placing the alloyed powders in an isothermal furnace having a press; applying pressure to the powders with the press for at least 30 minutes to form polycrystalline pellets; and maintaining the isothermal furnace at a temperature of at least 650° C.
Claim 45
Dependent Claim
26 words
The method of preparing a semiconductor alloy as defined in claim 31, further comprising the step of forming the mixture with the formula IrSb 3 .
Claim 46
Dependent Claim
31 words
The method of preparing a semiconductor alloy as defined in claim 31 further comprising the step of forming the mixture with the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 47
Independent Claim
99 words
A method of preparing a semiconductor alloy for use in fabricating thermoelectric elements from an approximately stoichiometric mixture comprising the steps of: placing elemental powders selected from the group consisting of Ir, Rh, Co, and Sb in a container to form the mixture; placing the container with the mixture into an isothermal furnace having a press; and applying pressure to the mixture with the press for at least 30 minutes while maintaining the temperature of the isothermal furnace at a temperature of at least 600° C. to form polycrystalline pellets having a skutterudite-type crystal lattice structure from the mixture.
Claim 48
Independent Claim
99 words
A method of preparing a semiconductor alloy for use in fabricating thermoelectric elements from an approximately stoichiometric mixture comprising the steps of: placing elemental powders selected from the group consisting of Ir, Rh, Co, and Sb in a container to form the mixture; placing the container with the mixture into an isothermal furnace having a press; and applying pressure to the mixture with the press for at least 30 minutes while maintaining the temperature of the isothermal furnace at a temperature of at least 600° C. to form polycrystalline pellets having a skutterudite-type crystal lattice structure from the mixture.
Claim 49
Dependent Claim
25 words
The method of preparing a semiconductor alloy as defined in claim 37 further comprising the steps of placing the mixture in a graphite die container.
Claim 50
Dependent Claim
26 words
The method of preparing a semiconductor alloy as defined in claim 37, further comprising the step of forming the mixture with the formula IrSb 3 .
Claim 51
Dependent Claim
31 words
The method of preparing a semiconductor alloy as defined in claim 39 further comprising the step of forming the mixture with the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 52
Dependent Claim
71 words
A radioisotope thermoelectric generator having a general purpose heat source and a cooling assembly with a thermoelectric device disposed therebetween comprising: a plurality of thermoelectric elements formed from at least two different types of semiconductor materials comprising: a portion of the thermoelectric elements formed from a P-type semiconductor material having a skutterudite-type crystal lattice structure; and the P-type semiconductor material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 53
Dependent Claim
71 words
A radioisotope thermoelectric generator having a general purpose heat source and a cooling assembly with a thermoelectric device disposed therebetween comprising: a plurality of thermoelectric elements formed from at least two different types of semiconductor materials comprising: a portion of the thermoelectric elements formed from a P-type semiconductor material having a skutterudite-type crystal lattice structure; and the P-type semiconductor material having the formula: Co.sub.1-x-y Rh.sub.x Ir.sub.y Sb.sub.3 wherein 0≦x≦1 and 0≦y≦1.
Claim 54
Dependent Claim
56 words
The radioisotope thermoelectric generator as defined in claim 41 further comprising another portion of the thermoelectric elements formed from an N-type semiconductor material selected from the group consisting of alloys of Bi-Sb alloys, Bi 2 Te 3 based alloys, PbTe based alloys, β-FeSi 2 based alloys, Ga 1-x In x Sb based alloys, and SiGe alloys.
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