WO2016185549A1 - Thermoelectric conversion material, thermoelectric conversion element and thermoelectric conversion module using same - Google Patents

Thermoelectric conversion material, thermoelectric conversion element and thermoelectric conversion module using same Download PDF

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WO2016185549A1
WO2016185549A1 PCT/JP2015/064244 JP2015064244W WO2016185549A1 WO 2016185549 A1 WO2016185549 A1 WO 2016185549A1 JP 2015064244 W JP2015064244 W JP 2015064244W WO 2016185549 A1 WO2016185549 A1 WO 2016185549A1
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thermoelectric conversion
conversion material
group
electrode
material member
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Japanese (ja)
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真 籔内
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株式会社日立製作所
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G41/00—Compounds of tungsten
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N11/00—Generators or motors not provided for elsewhere; Alleged perpetua mobilia obtained by electric or magnetic means
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/80—Constructional details
    • H10N10/85—Thermoelectric active materials
    • H10N10/851—Thermoelectric active materials comprising inorganic compositions
    • H10N10/855—Thermoelectric active materials comprising inorganic compositions comprising compounds containing boron, carbon, oxygen or nitrogen

Definitions

  • the present invention relates to a thermoelectric conversion material, a thermoelectric conversion element, and a thermoelectric conversion module using the same.
  • thermoelectric conversion element has been known for a long time as one of the methods for utilizing the energy of exhaust heat, and Bi2Te3 has been put into practical use as a relatively efficient thermoelectric conversion material at a temperature of 200 ° C. or lower.
  • Bi-Te-based materials have a figure of merit ZT> 1 and high conversion efficiency, but Bi and Te are both expensive, and Te is extremely toxic.
  • a conventional thermoelectric conversion element such as a Bi-Te system cannot be supplied to the market in a large quantity at a low cost and is generally unlikely to be widely spread. For this reason, what can be mass-produced, cost-reduced, and environmental load reduction is calculated
  • Non-Patent Document 1 discloses a thermoelectric conversion material based on a full Heusler alloy Fe2TiSi as a material system having a low environmental load. This is composed of elements with low environmental load and relatively low cost, such as Fe, Ti, Si, etc., and since it has a flat band in the conduction band, it is shown to be a promising material as an n-type thermoelectric material. ing. Full Heusler alloy is a material system that is valuable for industrial applications because it does not use toxic rare metals like Bi-Te materials. Further, Patent Document 1 discloses a thermoelectric conversion material having Fe and S as main components and having a pyrite structure as a material capable of realizing low environmental load and low cost.
  • Patent Document 1 nor Non-Patent Document 1 is a material having a flat band in the valence band. Therefore, a material system that can improve performance as a p-type thermoelectric conversion element with low environmental load and low cost has not yet been obtained. Accordingly, there is a demand for thermoelectric conversion as a thermoelectric conversion material that exhibits higher thermoelectric characteristics than conventional material systems, and that has low environmental load and low cost.
  • an object of the present invention is to obtain a p-type thermoelectric conversion material and a thermoelectric conversion element that can be reduced in environmental load and cost, and can obtain high thermoelectric conversion characteristics.
  • One aspect of the present invention for solving the above problems is at least one element selected from the group consisting of W, Mo and Cr, and at least one element selected from the group consisting of Si, Ge, Sn and C. and elemental beta, including oxygen, has a hexagonal structure of the space group P 6 3 / m, thermoelectric, wherein the volume V per atom is 12.4 ⁇ V ⁇ 13.4 ⁇ 3 It is a conversion material.
  • the hexagonal structure is a W 8 Sn 5 O 23 structure, and part or all of W which is the element ⁇ is substituted with at least one selected from the group consisting of Mo and Cr.
  • a part or all of Sn as the element ⁇ is substituted with at least one selected from the group consisting of Si, Ge, and C.
  • the composition of W 8 Sn 5 O 23 shows a typical ratio. Actually, if the ratio of the atomic percent of ⁇ and ⁇ is within the range of 3: 2 to 4: 3, the effect is close. I can expect.
  • thermoelectric conversion material At least one selected from the group consisting of V, Ti, Zr, Al, Ga, In, Li, Na, Ca, Li, Na and K is added to constitute a p-type thermoelectric conversion material. To do.
  • At least one selected from the group consisting of Cu, Ag, Fe, Mn, Co, Ni, P, As, Sb, and Bi is added to constitute an n-type thermoelectric conversion material.
  • the carrier density is in the range of 1 ⁇ 10 18 to 1 ⁇ 10 21 cm ⁇ 3 , preferably 1 ⁇ 10 19 to 1 ⁇ 10 21 cm ⁇ 3 .
  • the W 8 Sn 5 O 23 structure, W, Mo, Cr, Sn , Si, Ge, and W 8 (1-x) were introduced different elements A, B and C B
  • 8x Sn 5 (1-y) B 5y O 23-z the valence number density (VEC) is controlled.
  • thermoelectric conversion material member includes at least one element ⁇ selected from the group consisting of W, Mo and Cr, at least one element ⁇ selected from the group consisting of Si, Ge, Sn and C, and oxygen, has a hexagonal structure of the space group P 6 3 / m, the volume V per atom is 12.4 ⁇ V ⁇ 13.4 ⁇ 3.
  • the c direction of the main crystallites having a hexagonal crystal structure is oriented, and the orientation direction and the temperature gradient direction are parallel or perpendicular to each other.
  • thermoelectric conversion material member includes at least one element ⁇ selected from the group consisting of W, Mo and Cr, at least one element ⁇ selected from the group consisting of Si, Ge, Sn and C, and oxygen. wherein has a hexagonal structure of the space group P 6 3 / m, the volume V per atom is used a thermoelectric conversion material is 12.4 ⁇ V ⁇ 13.4 ⁇ 3.
  • the thermoelectric conversion element includes a first element in which the thermoelectric conversion material member is p-type and a second element in which the thermoelectric conversion material member is n-type, and the first electrode is a relatively high temperature side of the thermoelectric conversion material member
  • the second electrode is disposed on the relatively low temperature side of the thermoelectric conversion material member, the first electrode of the first element and the first electrode of the second element are connected in series, The second electrode of one element and the second electrode of the second element are connected in series.
  • thermoelectric conversion exhibiting a low environmental load and a low cost and exhibiting high thermoelectric conversion characteristics.
  • notations such as “first”, “second”, and “third” are attached to identify the constituent elements, and do not necessarily limit the number or order.
  • a number for identifying a component is used for each context, and a number used in one context does not necessarily indicate the same configuration in another context. Further, it does not preclude that a component identified by a certain number also functions as a component identified by another number.
  • FIG. 1 shows a crystal structure of W 8 Sn 5 O 23 which is an example of the present invention.
  • the crystal structure shown in FIG. 1 is a hexagonal crystal (space group: P 6 3 / m), and the unit cell contains 72 atoms.
  • W is a transition metal, and physical properties such as a band gap can be controlled by partially substituting W of the same group, such as Mo and Cr.
  • the thermoelectric characteristics can be controlled by partially replacing Sn with C, Si, or Ge of the same family.
  • composition of W 8 Sn 5 O 23 which is an embodiment of the present invention
  • the composition includes at least one element ⁇ selected from the group consisting of oxygen and oxygen, and the ratio of the atomic percent of ⁇ and ⁇ is in the range of 3: 2 to 4: 3. As described above, a part of ⁇ and ⁇ can be replaced within this range.
  • FIG. 2 shows an example of an embodiment of the present invention in which W and Sn are substituted with various elements.
  • FIG. 2 shows W 8 Sn 5 O 23 , W 8 Ge 5 O 23 , W 8 Si 5 O 23 , Mo 8 Sn 5 O 23 , Mo 8 Ge 5 O 23 , and Mo 8 Si 5 obtained by the first principle calculation. It shows the band structure of the O 23. The vertical axis indicates the energy level, and the horizontal axis indicates the position of the k point in the Brillouin Zone.
  • the bands near the top of the valence band of W 8 Sn 5 O 23 , W 8 Ge 5 O 23 , Mo 8 Sn 5 O 23 , and Mo 8 Ge 5 O 23 are from the ⁇ point to the M point.
  • a flat band appears in the direction.
  • Mo 8 Sn 5 O 23 has a flat band in the direction from the ⁇ point to the K point of the conduction band, and both n-type and p-type are high-efficiency thermoelectric conversion materials utilizing the flat band.
  • the energy level is 0. Since a flat band is observed in the vicinity of (Fermi level), thermoelectric characteristics are easily obtained. That is, since the density of states increases, the state occupied when the temperature changes is likely to change, the position of the Fermi level easily moves, and the thermoelectromotive force increases. In addition, these materials have no band in the vicinity of energy level 0 and take a semiconductor electronic state.
  • 3A to 3B show the temperature dependence of the Seebeck coefficient at each hole carrier density obtained by calculation.
  • 3A to 3B show the p-type and n-type, Sxx indicates the Seebeck coefficient in the in-plane direction (direction perpendicular to the c-axis in FIG. 1), and Szz indicates the perpendicular direction (FIG. 3).
  • 1 shows the Seebeck coefficient in the c-axis direction).
  • a high Seebeck coefficient close to 400 ⁇ V / K is exhibited at room temperature at a hole carrier density of 1 ⁇ 10 20 cm ⁇ 3. Further, as shown in FIG.
  • VEC valence number density
  • transition metal elements that have fewer valence electrons than W in the composition of W (8-x) M x Sn 5 O 23 (M is a substituted element) VEC can be changed by replacing W with La, Hf, Ta).
  • FIG. 4 is a diagram showing the relationship between VEC and power factor of W 8 Sn 5 O 23 .
  • a part of W or the like can be replaced with another element to control the positive / negative change amount ⁇ VEC of VEC.
  • Px indicates the power factor in the in-plane direction (direction perpendicular to the c-axis in FIG. 1)
  • Pz indicates the power factor in the perpendicular direction (c-axis direction in FIG. 1).
  • Such VEC control can use transition metal elements such as Zn, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu in addition to the above transition metal elements.
  • W may be replaced with Al, Ga, In, Tl, Zr, Nb, Mo, Ta.
  • VEC can be controlled by substituting Sn as well as W.
  • Elements such as B, Al, Ga, In, N, O, P, As, Sb, Bi, and S, which have a different valence electron number from Sn, can be used.
  • W (8-x) M x Sn (5-y) T y O 23- z of x, y, z is preferably in the range of (0 ⁇ x ⁇ 2,0 ⁇ y ⁇ 2,0 ⁇ z ⁇ 2).
  • thermal conductivity can be reduced in addition to the above VEC control.
  • substitution with heavy elements or light elements having an atomic weight different from W and Sn, which are components of W 8 Sn 5 O 23 as a parent phase, is effective. Therefore, the thermal conductivity can be reduced by substituting Sn with an element such as Sb, Bi, or Ba having an atomic weight larger than that of Sn.
  • the crystal structure of W 8 Sn 5 O 23 is hexagonal, it has anisotropic properties. As shown in FIG. 4, the power factor value varies depending on the direction. When ⁇ VEC> 0, the absolute value of the power factor (Pz) in the c-axis direction is high, and when ⁇ VEC ⁇ 0, it is perpendicular to the c-axis. The absolute value of the power factor (Px) in any direction increases. Therefore, thermoelectric conversion characteristics can be further increased by controlling the orientation in the crystal direction.
  • the c direction of the main crystal microcrystal that is hexagonal is oriented, and when the c axis direction of W 8 Sn 5 O 23 and the temperature gradient direction are parallel, n
  • the performance of the type thermoelectric conversion element can be improved. Further, when the c-axis direction and the temperature gradient direction are perpendicular to each other, the performance as a p-type can be increased.
  • FIG. 5 shows a correspondence table between selectable element valence electrons and elements.
  • elements M and T any element can be selected from the elements described in the table of FIG.
  • x and y are preferably in the range of (0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 2, ⁇ 2 ⁇ z ⁇ 2).
  • thermoelectromotive force in the thermoelectric conversion element depends on the electronic state of the substance. From the viewpoint of obtaining a high thermoelectromotive force, a material having a sharp change in state density near the Fermi level is preferable. In order to reduce the thermal conductivity, it is desirable that a plurality of elements and heavy elements are included in the crystal structure. From the above viewpoint, in the W 8 Sn 5 O 23 structure system containing the elements ⁇ and ⁇ as main components, for example, element substitution or element doping is performed, the volume per atom is controlled within a predetermined range, and the carrier density Adjust. Thereby, the outstanding thermoelectric conversion characteristic is realizable.
  • the volume per atom is a value obtained by dividing the volume of each crystal lattice by the number of constituent atoms.
  • the lattice constant can be adjusted by substituting some elements of W and Sn in W 8 Sn 5 O 23 .
  • W 8 Sn 5 O 23 by substituting a part of Sn is Group IV element in Ge and W 8 Sn 5-x Ge x O 23 in the crystals (0 ⁇ x ⁇ 5)
  • the volume per atom changes in the range of 12.60 ⁇ 3 to 13.18 ⁇ 3 according to the value of the substitution amount x, and the physical properties thereof change.
  • FIG. 6 is a graph showing the relationship between the volume per atom in the crystal and the power factor.
  • FIG. 6 (A) was replaced with N-type, the Sn 5 of Mo 8 Sn 5 O 23 to Ge 5 (square plots). Also, by substituting Sn 5 of W 8 Sn 5 O 23 to Ge 5, Si 5 (plot circles).
  • FIG. 6 (B) P-type, and replacing the Sn 5 effective image Mo 8 Sn 5 O 23 (square plots). Also, by substituting Sn 5 of W 8 Sn 5 O 23 (plot circles).
  • plotted points was replaced all Sn 5 to one other element, may be substituted Sn 5 at two or more elements may be partially replaced only.
  • N-type from FIG 6 (A) is the power factor with a volume per atom in the crystal is increased also increased, and has a maximum at about 13.20 ⁇ 3.
  • the P type is the maximum at about 12.5 cm 3 . Therefore, both P-type and N-type materials can be adjusted to a material system having extremely excellent thermoelectric conversion in the range of 12.4 to 13.40 cm 3 . From the data in FIG. 6, a significant relationship is recognized between the volume per atom and the power factor.
  • thermoelectric conversion material can be easily confirmed by X-ray diffraction (XRD).
  • XRD X-ray diffraction
  • a lattice image can be observed with an electron microscope such as TEM (TransmissionTransElectron Miroscop) or a single crystal or polycrystal structure can be confirmed from a spot pattern or ring pattern in an electron beam diffraction image.
  • Composition distribution can be confirmed using EPMA (Electron Probe Probe MicroAnalyser) such as EDX (Energy Dispersive X-ray Spectroscopy), SIMS (Secondary Ionization Mass Mass Spectrometer), X-ray photoelectron spectroscopy, ICP (Inductively Coupled Plasma), etc.
  • EPMA Electrodet Probe MicroAnalyser
  • EDX Electronic X
  • SIMS Secondary Ionization Mass Mass Mass Spectrometer
  • ICP Inductively Coupled Plasma
  • Information on the state density of the material can be confirmed by ultraviolet photoelectron spectroscopy or X-ray photoelectron spectroscopy.
  • the electrical conductivity and carrier density can be confirmed by electrical measurement using the four-terminal method and Hall effect measurement.
  • the Seebeck coefficient can be confirmed by giving a temperature difference to both ends of the sample and measuring the voltage difference between both ends.
  • the thermal conductivity can be confirmed by a laser flash method.
  • FIG. 7 shows the result of analyzing the WSnO material which is an example of the present invention by X-ray diffraction. The result reflecting the composition constituted by the above examination is obtained.
  • Example of manufacturing method and measurement> Hereinafter, an example of sample preparation using an embodiment of the present invention will be shown.
  • the manufacturing example is an example, and the manufacturing conditions are not limited thereto.
  • Example preparation example 1 A 99.9% pure WO 2 powder, 99.99% SnO 2 and 99.99% Sn powder and Sb powder were mixed at a composition ratio of 16: 7: 2.9: 0.1, and an alloy was produced by mechanical alloying. Later, when VEC is calculated from the composition of the produced material, 206.05 is obtained.
  • sample preparation example 2 99.9% pure WO 2 powder, 99.99 SnO 2 and 99.99 Sn powder were mixed at a composition ratio of 16: 7: 3, placed in a quartz tube, and heat-treated at 1000 ° C. for 24 hours in a vacuum atmosphere. Thereafter, the sample was pulverized using a ball mill. As a result of X-ray diffraction analysis of the powder sample, a crystal structure peak derived from the W 8 Sn 5 O 23 structure can be observed.
  • Example preparation example 3 99.9% purity WO 2 powder, 99.9% purity MoO 2 powder, 99.99% SnO 2 and 99.99% Sn powder were mixed in a ratio of 15: 1: 7: 3 and put into a quartz tube. Heat treatment was performed in a vacuum atmosphere at 700 ° C. for 24 hours, and then the sample was pulverized using a ball mill. As a result of X-ray diffraction analysis of the powder sample, it was a W 8 Sn 5 O 23 structure. When VEC is calculated from a powder sample of W 7.5 Mo 0.5 Sn 5 O 23 , it is 206.0.
  • Example preparation example 4 W 6 Mo 2 Sn 5 O 23 , W 7 CrSn 5 O 23 , W 7.9 Ti 0.1 Sn 5 O 23 , W 7.9
  • W is partially replaced with Mo, Cr, Ti, Ta. Ta 0.1 Sn 5 O 23 was produced.
  • Example preparation example 5 99.9% pure WO 2 powder, 99.9% pure MoO 2 powder, 99.99% SnO 2 , 99.99% Sn powder and 99.99% Ge powder in a ratio of 15: 1: 7: 2: 1
  • the mixture was mixed, put into a quartz tube, heat-treated in a vacuum atmosphere at 700 ° C. for 24 hours, and then the sample was pulverized using a ball mill.
  • As a result of X-ray diffraction analysis of the powder sample it was a W 8 Sn 5 O 23 structure.
  • VEC is calculated from a powder sample of W 8 Sn 3.33 Ge 1.67 O 23 , it is 206.0.
  • Example preparation example 6 Using a W 8 Sn 5 O 23 target, a thin film with a film thickness of about 300 nm is fabricated on a Si substrate with a thermal oxide film, and heat treatment is performed in a nitrogen atmosphere at 1000 ° C. for 1 hour. It was. As a result of X-ray diffraction analysis of the thin film, a peak of the W 8 Sn 5 O 23 structure was observed.
  • Example measurement example 1 A temperature difference between room temperature and 20 ° C. was made on the samples prepared in Sample Preparation Example 1 and Sample Preparation Example 2, and the Seebeck coefficient was measured. As a result, high Seebeck coefficients of ⁇ 250 V ⁇ / K and 250 ⁇ V / K were obtained, respectively. Therefore, according to this example, it was confirmed that the VEC was changed depending on the doping amount, the Seebeck coefficient could be modulated, and the material system had a high thermoelectromotive force as p-type and n-type. The thermal conductivities were 1.0 W / Km and 0.9 W / Km, respectively.
  • the sample preparation method may be a vacuum evaporation method such as molecular beam epitaxy other than the present embodiment, or chemical vapor deposition.
  • a method for sintering the powder material a discharge plasma sintering method, a hot press method, a hot forge method, or the like may be used.
  • the present embodiment by adding an element having a different valence number by doping and controlling the number of valence electrons of the compound, the number of electrons occupied by the band is changed, the electronic state at the Fermi level is modulated, and high Thermoelectromotive force can be realized.
  • the present embodiment by combining materials that are inexpensive and less likely to be depleted, it is possible to produce a low-cost and non-toxic thermoelectric conversion material.
  • FIG. 8 shows an example in which the material described in the above embodiment is used for the thermoelectric conversion element 100.
  • 104 is the thermoelectric conversion material described in the above embodiment
  • 102a is a high temperature side electrode that is in electrical contact with the thermoelectric conversion material 104
  • 102b is a low temperature side electrode that is in electrical contact with the thermoelectric conversion material 104
  • 120 and 130 are current paths. (The current direction is different depending on whether the thermoelectric conversion material 104 is P-type or N-type).
  • FIG. 9 shows another example in which the material described in the above embodiment is used for the thermoelectric conversion element 200.
  • 103 and 104 are the thermoelectric conversion materials described in the above embodiments, and both P-type (103) and N-type (104) are used.
  • Reference numeral 102c denotes a high temperature side electrode in electrical contact with the thermoelectric conversion material 104
  • reference numerals 102b and 102d denote low temperature side electrodes in electrical contact with the thermoelectric conversion material 104
  • reference numeral 140 denotes a current path.
  • FIG. 10 shows a perspective view of a thermoelectric conversion module 300 configured by connecting a plurality of thermoelectric conversion elements 200 shown in FIG. 9 in series. A part of the upper portion of the housing 101 is cut away so that the inside can be seen. The housing 101 also plays a role of transferring heat to the thermoelectric conversion element 200. The thermoelectric conversion element 200 is in contact with the housing 101 at the upper or lower electrode 102.
  • the present invention is not limited to the above-described embodiment, and includes various modifications.
  • a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.
  • thermoelectric conversion materials that obtain electric power from thermal energy, thermoelectric conversion elements, and thermoelectric conversion modules using the same.
  • thermoelectric conversion element 102a High temperature side electrode 102b: Low temperature side electrode 103: P-type thermoelectric conversion material 104: N-type thermoelectric conversion material

Abstract

Disclosed are: a thermoelectric conversion material which is characterized by containing oxygen, at least one element α selected from the group consisting of W, Mo and Cr, and at least one element β selected from the group consisting of Si, Ge, Sn and C, while having a hexagonal structure of the space group P 63/m and a volume per one atom V satisfying 12.4 ≤ V 13.4 Å3; a thermoelectric conversion element using this thermoelectric conversion material; and a thermoelectric conversion module using this thermoelectric conversion element. Consequently, environmental load and cost can to be reduced, and thermoelectric conversion exhibiting high thermoelectric conversion characteristics is able to be achieved.

Description

熱電変換材料、熱電変換素子、及びそれを用いた熱電変換モジュールThermoelectric conversion material, thermoelectric conversion element, and thermoelectric conversion module using the same
　本発明は、熱電変換材料、熱電変換素子、及びそれを用いた熱電変換モジュールに関する。 The present invention relates to a thermoelectric conversion material, a thermoelectric conversion element, and a thermoelectric conversion module using the same.
　化石燃料に依存しないクリーンな発電システムとして、地熱や排熱など、これまであまり利用されていないエネルギー源が求められている。地下鉄や変電所において排出される、２００℃以下の比較的低温の排熱は、エネルギー総量が膨大であり、有効なエネルギー回収技術の確立が求められている。 As a clean power generation system that does not rely on fossil fuels, energy sources that have not been used so far, such as geothermal and exhaust heat, are required. The relatively low-temperature exhaust heat of 200 ° C. or less discharged in subways and substations has an enormous amount of energy, and the establishment of effective energy recovery technology is required.
　排熱のエネルギー利用方法の一つとして、古くから熱電変換素子が知られており、現在、２００℃以下の温度で比較的効率の良い熱電変換材料として、Ｂｉ２Ｔｅ３が実用化されている。Ｂｉ－Ｔｅ系材料は性能指数ＺＴ＞１と変換効率が高いが、Ｂｉ及びＴｅはともに高価であり、またＴｅは極めて毒性が強いものである。このため、Ｂｉ－Ｔｅ系のような従来の熱電変換素子では、安価に大量かつ安定的に市場に供給できず、一般に広く普及させられる可能性は低い。このため、熱電変換素子として、大量生産や低コスト化、環境負荷低減できるものが求められている。 A thermoelectric conversion element has been known for a long time as one of the methods for utilizing the energy of exhaust heat, and Bi2Te3 has been put into practical use as a relatively efficient thermoelectric conversion material at a temperature of 200 ° C. or lower. Bi-Te-based materials have a figure of merit ZT> 1 and high conversion efficiency, but Bi and Te are both expensive, and Te is extremely toxic. For this reason, a conventional thermoelectric conversion element such as a Bi-Te system cannot be supplied to the market in a large quantity at a low cost and is generally unlikely to be widely spread. For this reason, what can be mass-produced, cost-reduced, and environmental load reduction is calculated | required as a thermoelectric conversion element.
　環境低負荷である材料系として、フルホイスラー合金Ｆｅ２ＴｉＳｉを基本とした熱電変換材料が非特許文献１に開示されている。これは、Ｆｅ、Ｔｉ、Ｓｉなどの環境低負荷でかつ比較的低コストな元素によって構成されており、伝導帯にフラットバンドを有するため、ｎ型熱電材料として有望な材料であることが示されている。フルホイスラー合金は、Ｂｉ－Ｔｅ系材料のように有毒なレアメタルを使用しないため、産業応用上価値のある材料系である。また、低環境負荷、低コスト化を実現できるものとして、Ｆｅ及びＳを主成分とした、パイライト構造を有する熱電変換材料も特許文献１に開示されている。 Non-Patent Document 1 discloses a thermoelectric conversion material based on a full Heusler alloy Fe2TiSi as a material system having a low environmental load. This is composed of elements with low environmental load and relatively low cost, such as Fe, Ti, Si, etc., and since it has a flat band in the conduction band, it is shown to be a promising material as an n-type thermoelectric material. ing. Full Heusler alloy is a material system that is valuable for industrial applications because it does not use toxic rare metals like Bi-Te materials. Further, Patent Document 1 discloses a thermoelectric conversion material having Fe and S as main components and having a pyrite structure as a material capable of realizing low environmental load and low cost.
　しかしながら、特許文献１、及び非特許文献１は、いずれも価電子帯にフラットバンドを有する材料ではない。そのため、低環境負荷及び低コストでp型熱電変換素子としての高性能化が可能な材料系は、いまだ得られていない。従って、熱電変換材料とし従来の材料系以上に高い熱電特性を示し、なおかつ低環境負荷及び低コストの熱電変換が求められている。 However, neither Patent Document 1 nor Non-Patent Document 1 is a material having a flat band in the valence band. Therefore, a material system that can improve performance as a p-type thermoelectric conversion element with low environmental load and low cost has not yet been obtained. Accordingly, there is a demand for thermoelectric conversion as a thermoelectric conversion material that exhibits higher thermoelectric characteristics than conventional material systems, and that has low environmental load and low cost.
特開２０１３－２１９２１８号公報JP 2013-219218 A
　そこで、本発明の目的は、低環境負荷及び低コスト化が可能であり、かつ高い熱電変換特性を得られるｐ型の熱電変換材料及び熱電変換素子を得ることを目的とする。 Therefore, an object of the present invention is to obtain a p-type thermoelectric conversion material and a thermoelectric conversion element that can be reduced in environmental load and cost, and can obtain high thermoelectric conversion characteristics.
　上記課題を解決するための本発明の一側面は、W、Mo及びCrからなる群から選ばれる少なくとも一種以上の元素αと、Si、Ge、Sn及びCからなる群から選ばれる少なくとも一種以上の元素βと、酸素を含み、空間群P 63/mの六方晶構造を有しており、１原子当りの体積Ｖが１２．４≦Ｖ≦１３．４Å３であることを特徴とする熱電変換材料である。 One aspect of the present invention for solving the above problems is at least one element selected from the group consisting of W, Mo and Cr, and at least one element selected from the group consisting of Si, Ge, Sn and C. and elemental beta, including oxygen, has a hexagonal structure of the space group P 6 3 / m, thermoelectric, wherein the volume V per atom is 12.4 ≦ V ≦ 13.4Å 3 It is a conversion material.
　本発明の好適なる態様では、六方晶構造はW8Sn5O23構造であり、元素αであるWの一部又は全部が、Mo及びCrからなる群から選ばれる少なくとも一種で置換されるか、元素βであるSnの一部又は全部が、Si、Ge、及びCからなる群から選ばれる少なくとも一種で置換されている。W8Sn5O23の組成は典型的な比率を示しており、実際には、αとβの原子パーセントの比率が、３：２～４：３の範囲内の構造であれば近い効果を期待できる。 In a preferred embodiment of the present invention, the hexagonal structure is a W 8 Sn 5 O 23 structure, and part or all of W which is the element α is substituted with at least one selected from the group consisting of Mo and Cr. In addition, a part or all of Sn as the element β is substituted with at least one selected from the group consisting of Si, Ge, and C. The composition of W 8 Sn 5 O 23 shows a typical ratio. Actually, if the ratio of the atomic percent of α and β is within the range of 3: 2 to 4: 3, the effect is close. I can expect.
　本発明の具体例においては、V、Ti、Zr、Al、Ga、In、Li、Na、Ca、Li、Na及びKからなる群から選ばれる少なくとも一種が添加され、p型熱電変換材料を構成する。 In a specific example of the present invention, at least one selected from the group consisting of V, Ti, Zr, Al, Ga, In, Li, Na, Ca, Li, Na and K is added to constitute a p-type thermoelectric conversion material. To do.
　本発明の他の具体例においては、Cu、Ag、Fe、Mn、Co、Ni、P、As、Sb、Biからなる群から選ばれる少なくとも一種が添加され、n型熱電変換材料を構成する。 In another specific example of the present invention, at least one selected from the group consisting of Cu, Ag, Fe, Mn, Co, Ni, P, As, Sb, and Bi is added to constitute an n-type thermoelectric conversion material.
　本発明の他の具体例では、キャリア密度が１×１０１８～１×１０２１ｃｍ－３、好ましくは、１×１０１９～１×１０２１ｃｍ－３の範囲である。 In another embodiment of the invention, the carrier density is in the range of 1 × 10 18 to 1 × 10 21 cm −3 , preferably 1 × 10 19 to 1 × 10 21 cm −3 .
　本発明の他の具体例では、W8Sn5O23構造に、W、Mo、Cr、Sn、Si、Ge、及びCとは異なる元素A,Bを導入したW8(1-x)B8xSn5(1-y)B5yO23-zを用いることによって、価電子数密度（VEC）を制御する。 In another embodiment of the present invention, the W 8 Sn 5 O 23 structure, W, Mo, Cr, Sn , Si, Ge, and W 8 (1-x) were introduced different elements A, B and C B By using 8x Sn 5 (1-y) B 5y O 23-z , the valence number density (VEC) is controlled.
　本発明の他の一側面は、熱電変換材料部材と、熱電変換材料部材に電気的に接触する第1の電極と、熱電変換材料部材に電気的に接触する第２の電極と、を備え、熱電変換材料部材に与えられる温度勾配により、前記第1の電極と前記第2の電極の間に電流を生ぜしめる熱電変換素子である。熱電変換材料部材は、W、Mo及びCrからなる群から選ばれる少なくとも一種以上の元素αと、Si、Ge、Sn及びCからなる群から選ばれる少なくとも一種以上の元素βと、酸素を含み、空間群P 63/mの六方晶構造を有しており、１原子当りの体積Ｖが１２．４≦Ｖ≦１３．４Å３である。 Another aspect of the present invention includes a thermoelectric conversion material member, a first electrode that is in electrical contact with the thermoelectric conversion material member, and a second electrode that is in electrical contact with the thermoelectric conversion material member, The thermoelectric conversion element generates an electric current between the first electrode and the second electrode by a temperature gradient applied to the thermoelectric conversion material member. The thermoelectric conversion material member includes at least one element α selected from the group consisting of W, Mo and Cr, at least one element β selected from the group consisting of Si, Ge, Sn and C, and oxygen, has a hexagonal structure of the space group P 6 3 / m, the volume V per atom is 12.4 ≦ V ≦ 13.4Å 3.
　好適な具体例では、六方晶構造となる主成分の微結晶のc方向が配向しており、その配向方向と温度勾配方向とが平行または垂直であるように配置される。 In a preferred specific example, the c direction of the main crystallites having a hexagonal crystal structure is oriented, and the orientation direction and the temperature gradient direction are parallel or perpendicular to each other.
　また、本発明の他の一側面は、熱電変換材料部材と、熱電変換材料部材に電気的に接触する第1の電極と、熱電変換材料部材に電気的に接触する第２の電極と、を備え、熱電変換材料部材に与えられる温度勾配により、第１の電極と第２の電極の間に電流を生ぜしめる熱電変換素子を複数用いた熱電変換モジュールである。上記の熱電変換材料部材は、W、Mo及びCrからなる群から選ばれる少なくとも一種以上の元素αと、Si、Ge、Sn及びCからなる群から選ばれる少なくとも一種以上の元素βと、酸素を含み、空間群P 63/mの六方晶構造を有しており、１原子当りの体積Ｖが１２．４≦Ｖ≦１３．４Å３である熱電変換材料を用いている。熱電変換素子は、熱電変換材料部材がp型である第１の素子と、熱電変換材料部材がn型である第２の素子を含み、第１の電極は熱電変換材料部材の比較的高温側に配置され、第２の電極は熱電変換材料部材の比較的低温側に配置され、第１の素子の第１の電極と、第２の素子の第１の電極とが、直列接続され、第１の素子の第２の電極と、第２の素子の第２の電極とが、直列接続されて構成される。 Another aspect of the present invention includes a thermoelectric conversion material member, a first electrode that is in electrical contact with the thermoelectric conversion material member, and a second electrode that is in electrical contact with the thermoelectric conversion material member. And a thermoelectric conversion module using a plurality of thermoelectric conversion elements that generate a current between the first electrode and the second electrode due to a temperature gradient applied to the thermoelectric conversion material member. The thermoelectric conversion material member includes at least one element α selected from the group consisting of W, Mo and Cr, at least one element β selected from the group consisting of Si, Ge, Sn and C, and oxygen. wherein has a hexagonal structure of the space group P 6 3 / m, the volume V per atom is used a thermoelectric conversion material is 12.4 ≦ V ≦ 13.4Å 3. The thermoelectric conversion element includes a first element in which the thermoelectric conversion material member is p-type and a second element in which the thermoelectric conversion material member is n-type, and the first electrode is a relatively high temperature side of the thermoelectric conversion material member The second electrode is disposed on the relatively low temperature side of the thermoelectric conversion material member, the first electrode of the first element and the first electrode of the second element are connected in series, The second electrode of one element and the second electrode of the second element are connected in series.
　本発明によれば、低環境負荷及び低コスト化が可能で、高い熱電変換特性を示す熱電変換を実現することができる。 According to the present invention, it is possible to realize a thermoelectric conversion exhibiting a low environmental load and a low cost and exhibiting high thermoelectric conversion characteristics.
W8Sn5O23の結晶構造を示す模式図Schematic showing the crystal structure of W 8 Sn 5 O 23 本発明の実施例のエネルギーバンド図Energy band diagram of an embodiment of the present invention 計算によって得られたホールキャリア密度１×１０２０におけるゼーベック係数の温度依存性を示すグラフ図The graph which shows the temperature dependence of the Seebeck coefficient in hole carrier density 1x10 20 obtained by calculation 計算によって得られたホールキャリア密度１×１０２１におけるゼーベック係数の温度依存性を示すグラフ図The graph which shows the temperature dependence of the Seebeck coefficient in the hole carrier density 1 * 10 < 21 > obtained by calculation W8Sn5O23のゼーベック係数とパワーファクターの関係を示すグラフ図Graph showing the relationship between the Seebeck coefficient and power factor of W 8 Sn 5 O 23 選択可能な元素の価電子数と元素の対応を示す表図Table showing the correspondence between the number of valence electrons and selectable elements 結晶中の１原子当りの体積とパワーファクターの関係を示すグラフ図Graph showing the relationship between the volume per atom in the crystal and the power factor 本発明の実施例のWSnO系材料をX線回折により分析した結果を示すグラフ図The graph figure which shows the result of having analyzed WSnO type material of the example of this invention by X ray diffraction 本発明の実施例である熱電変換素子の構成図Configuration diagram of thermoelectric conversion element which is an embodiment of the present invention 本発明の実施例である熱電変換素子の他の構成図The other block diagram of the thermoelectric conversion element which is an Example of this invention 本発明の実施例である熱電変換モジュールの構成斜視図The structure perspective view of the thermoelectric conversion module which is an Example of this invention
　実施の形態について、図面を用いて詳細に説明する。ただし、本発明は以下に示す実施の形態の記載内容に限定して解釈されるものではない。本発明の思想ないし趣旨から逸脱しない範囲で、その具体的構成を変更し得ることは当業者であれば容易に理解される。 Embodiments will be described in detail with reference to the drawings. However, the present invention is not construed as being limited to the description of the embodiments below. Those skilled in the art will readily understand that the specific configuration can be changed without departing from the spirit or the spirit of the present invention.
　以下に説明する発明の構成において、同一部分又は同様な機能を有する部分には同一の符号を異なる図面間で共通して用い、重複する説明は省略することがある。 In the structure of the invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and redundant description may be omitted.
　本明細書等における「第１」、「第２」、「第３」などの表記は、構成要素を識別するために付するものであり、必ずしも、数または順序を限定するものではない。また、構成要素の識別のための番号は文脈毎に用いられ、一つの文脈で用いた番号が、他の文脈で必ずしも同一の構成を示すとは限らない。また、ある番号で識別された構成要素が、他の番号で識別された構成要素の機能を兼ねることを妨げるものではない。 In this specification and the like, notations such as “first”, “second”, and “third” are attached to identify the constituent elements, and do not necessarily limit the number or order. In addition, a number for identifying a component is used for each context, and a number used in one context does not necessarily indicate the same configuration in another context. Further, it does not preclude that a component identified by a certain number also functions as a component identified by another number.
　図面等において示す各構成の位置、大きさ、形状、範囲などは、発明の理解を容易にするため、実際の位置、大きさ、形状、範囲などを表していない場合がある。このため、本発明は、必ずしも、図面等に開示された位置、大きさ、形状、範囲などに限定されない。 The position, size, shape, range, etc. of each component shown in the drawings and the like may not represent the actual position, size, shape, range, etc. in order to facilitate understanding of the invention. For this reason, the present invention is not necessarily limited to the position, size, shape, range, and the like disclosed in the drawings and the like.
　＜１．材料組成の検討＞
　図１に、本発明の一実施例であるW8Sn5O23の結晶構造を示す。図１に示す結晶構造は、六方晶（空間群：P 63/m）であり、ユニットセルに７２個の原子を含んでいる。このような複雑な結晶構造を有する材料系は、fcc構造やbcc構造に比べユニットセルのサイズが大きく、複雑な結晶構造であり、低い熱伝導率が期待できる。Wは遷移金属であり、同族のMo,CrなどをWに一部置換することによってバンドギャップなどの物性値を制御可能となる。また、Snも同族のC、Si、Geで一部置換することによって熱電特性を制御可能となる。従って、Mg、Sr、Ba、Ge、Snなどの元素置換が可能であり、W8(1-x)A8xSn5(1-y)B5yO23-z（A=Mg,Sr,Ba,　B=C,Ge,Sn）となる組成で各種元素置換が可能である。 <1. Study of material composition>
FIG. 1 shows a crystal structure of W 8 Sn 5 O 23 which is an example of the present invention. The crystal structure shown in FIG. 1 is a hexagonal crystal (space group: P 6 3 / m), and the unit cell contains 72 atoms. Such a material system having a complicated crystal structure has a larger unit cell size than the fcc structure and the bcc structure, has a complicated crystal structure, and can be expected to have a low thermal conductivity. W is a transition metal, and physical properties such as a band gap can be controlled by partially substituting W of the same group, such as Mo and Cr. In addition, the thermoelectric characteristics can be controlled by partially replacing Sn with C, Si, or Ge of the same family. Therefore, element substitution such as Mg, Sr, Ba, Ge, Sn is possible, and W 8 (1-x) A 8x Sn 5 (1-y) B 5y O 23 -z (A = Mg, Sr, Ba , B = C, Ge, Sn), and various element substitutions are possible.
　本発明の一実施例であるW8Sn5O23の組成を一般化して示すと、W、Mo及びCrからなる群から選ばれる少なくとも一種以上の元素αと、Si、Ge、Sn及びCからなる群から選ばれる少なくとも一種以上の元素βと、酸素を含み、αとβの原子パーセントの比率が３：２～４：３の範囲内の構成となる。なお、αとβの一部を、この範囲内で置換可能であることは、上記したとおりである。 When generalizing the composition of W 8 Sn 5 O 23 which is an embodiment of the present invention, at least one element α selected from the group consisting of W, Mo and Cr, and Si, Ge, Sn and C The composition includes at least one element β selected from the group consisting of oxygen and oxygen, and the ratio of the atomic percent of α and β is in the range of 3: 2 to 4: 3. As described above, a part of α and β can be replaced within this range.
　図２に、WやSnを種々の元素で置換した、本発明の実施例の例を示す。図２は第一原理計算によって得られたW8Sn5O23、W8Ge5O23、W8Si5O23、Mo8Sn5O23、Mo8Ge5O23、Mo8Si5O23のバンド構造を示している。縦軸がエネルギーレベル、横軸はブリュアンゾーン（Brillouin Zone）内における、k点の位置を示す。図２に示すように、W8Sn5O23、W8Ge5O23、Mo8Sn5O23、Mo8Ge5O23の価電子帯の頂上付近のバンドはΓ点からM点の方向にフラットなバンドが現れる。また、Mo8Sn5O23は伝導帯のΓ点からK点の方向にフラットバンドが現れており、n型p型ともにフラットバンドを活用した高効率熱電変換材料となる。 FIG. 2 shows an example of an embodiment of the present invention in which W and Sn are substituted with various elements. FIG. 2 shows W 8 Sn 5 O 23 , W 8 Ge 5 O 23 , W 8 Si 5 O 23 , Mo 8 Sn 5 O 23 , Mo 8 Ge 5 O 23 , and Mo 8 Si 5 obtained by the first principle calculation. It shows the band structure of the O 23. The vertical axis indicates the energy level, and the horizontal axis indicates the position of the k point in the Brillouin Zone. As shown in FIG. 2, the bands near the top of the valence band of W 8 Sn 5 O 23 , W 8 Ge 5 O 23 , Mo 8 Sn 5 O 23 , and Mo 8 Ge 5 O 23 are from the Γ point to the M point. A flat band appears in the direction. Mo 8 Sn 5 O 23 has a flat band in the direction from the Γ point to the K point of the conduction band, and both n-type and p-type are high-efficiency thermoelectric conversion materials utilizing the flat band.
　このように、W8Sn5O23、W8Ge5O23、W8Si5O23、Mo8Sn5O23、Mo8Ge5O23、Mo8Si5O23では、エネルギーレベル０（フェルミレベル）近傍で、フラットなバンドが観測されるため、熱電特性が得やすい。すなわち、状態密度が大きくなるため、温度が変化したときに占有する状態が変化しやすく、フェルミレベルの位置が動きやすく、熱起電力が大きくなると考えられる。また、これらの材料では、エネルギーレベル０近傍にバンドがなく、半導体的な電子状態をとる。 Thus, in W 8 Sn 5 O 23 , W 8 Ge 5 O 23 , W 8 Si 5 O 23 , Mo 8 Sn 5 O 23 , Mo 8 Ge 5 O 23 , and Mo 8 Si 5 O 23 , the energy level is 0. Since a flat band is observed in the vicinity of (Fermi level), thermoelectric characteristics are easily obtained. That is, since the density of states increases, the state occupied when the temperature changes is likely to change, the position of the Fermi level easily moves, and the thermoelectromotive force increases. In addition, these materials have no band in the vicinity of energy level 0 and take a semiconductor electronic state.
　＜２．キャリア密度の検討＞
　図３Ａ～図３Ｂは、計算によって得られた各ホールキャリア密度におけるゼーベック係数の温度依存性を示す。なお、図３Ａ～図３Ｂでは、p型およびn型について示しており、Sxxは、面内方向（図１のc軸に垂直な方向）のゼーベック係数を示し、Szzは、面直方向（図１のc軸方向）のゼーベック係数を示す。図３Ａに示すように、1×1020cm-3のホールキャリア密度において、室温で400μV/K近い高いゼーベック係数を示す。また、図３Ｂに示すように、1×1021cm-3のホールキャリア密度においても200μV/Kの高いゼーベック係数を示すことがわかる。図３Ａおよび図３Ｂから、キャリア密度の増大とともにゼーベック係数の絶対値は減少する傾向があるため、絶対値で２００～３００以上の高いゼーベック係数を得るために1×1021cm-3以下のキャリア密度にするのが望ましい。また、電気伝導性を考慮すると、1×1018cm-3以上、好ましくは1×1019cm-3以上のキャリア密度にするのが望ましい。したがって、キャリア密度が1×1018～1×1021cm-3、好ましくは1×1019～1×1021cm-3の範囲であることが望ましい。 <2. Examination of carrier density>
3A to 3B show the temperature dependence of the Seebeck coefficient at each hole carrier density obtained by calculation. 3A to 3B show the p-type and n-type, Sxx indicates the Seebeck coefficient in the in-plane direction (direction perpendicular to the c-axis in FIG. 1), and Szz indicates the perpendicular direction (FIG. 3). 1 shows the Seebeck coefficient in the c-axis direction). As shown in FIG. 3A, a high Seebeck coefficient close to 400 μV / K is exhibited at room temperature at a hole carrier density of 1 × 10 20 cm −3. Further, as shown in FIG. 3B, it can be seen that a high Seebeck coefficient of 200 μV / K is exhibited even at a hole carrier density of 1 × 10 21 cm −3. From FIG. 3A and FIG. 3B, since the absolute value of the Seebeck coefficient tends to decrease as the carrier density increases, a carrier of 1 × 10 21 cm −3 or less in order to obtain a high Seebeck coefficient of 200 to 300 or more in absolute value The density is desirable. In consideration of electrical conductivity, it is desirable to set the carrier density to 1 × 10 18 cm −3 or more, preferably 1 × 10 19 cm −3 or more. Therefore, it is desirable that the carrier density is in the range of 1 × 10 18 to 1 × 10 21 cm −3, preferably 1 × 10 19 to 1 × 10 21 cm −3.
　上記のようなキャリア密度に制御するために、適切なドーピングを行う必要があるが、その設計指針として、価電子数密度（VEC）を使うことが可能である。W8Sn5O23の化学量論組成における総価電子数は、Wの価電子数nW=6、Snの価電子数nSn=4、Oの価電子数nO=6よりVEC=(8×nW＋5×nSn＋23×nO)=206となる。また、WおよびSnとは異なる元素A,Bを導入したW8(1-x)B8xSn5(1-y)B5yO23-zを作ることによってVECを制御することが可能である。VECを206以下にすることにより、p型の性質を発現させ、VECを206以上にすることによってn型を作ることが可能となる。 In order to control the carrier density as described above, it is necessary to perform appropriate doping. As a design guideline, valence number density (VEC) can be used. The total valence electron number in the stoichiometric composition of W 8 Sn 5 O 23 is as follows: W valence electron number n W = 6, Sn valence electron number n Sn = 4, O valence electron number n O = 6, VEC = (8 × n W + 5 × n Sn + 23 × n O ) = 206. It is also possible to control VEC by making W 8 (1-x) B 8x Sn 5 (1-y) B 5y O 23-z into which elements A and B different from W and Sn are introduced. . By setting VEC to 206 or less, p-type properties can be expressed, and by setting VEC to 206 or more, n-type can be produced.
　VEC制御の一例として、W(8-x)MxSn5O23（Mは置換元素）の組成において、Wより価電子数が少ない遷移金属元素（Sc、Ti、V、Y、Zr、Nb、La、Hf、Ta）でWを置き換えることによってVECを変化させることができる。Wの一部をTaで置換した場合、Wの価電子数nW=6、Snの価電子数nSn=4、Taの価電子数nTa=5であるためVEC=((8-x)×nW＋5×nSn+x×nTa＋23×nO)=206-xとなる。従って、Taの置換量に応じてVECを変化させることができ、x=0.1のとき、VEC=205となる。 As an example of VEC control, transition metal elements (Sc, Ti, V, Y, Zr, Nb) that have fewer valence electrons than W in the composition of W (8-x) M x Sn 5 O 23 (M is a substituted element) VEC can be changed by replacing W with La, Hf, Ta). When a part of W is replaced with Ta, the number of valence electrons of W is n W = 6, the number of valence electrons of Sn is n Sn = 4, and the number of valence electrons of Ta is n Ta = 5. ) × n W + 5 × n Sn + x × n Ta + 23 × n O ) = 206−x. Therefore, VEC can be changed according to the amount of Ta substitution. When x = 0.1, VEC = 205.
　図４は、W8Sn5O23のVECとパワーファクターの関係を示す図である。上述のように、W等の一部を他の元素で置換してVECの正負の変化量ΔVECを制御することができる。VEC=205（ΔVEC=－1）のとき、図４に示すようにPx方向のパワーファクターを大きくする調整が可能となる。VEC=207（ΔVEC=1）のとき、図４に示すようにPz方向のパワーファクターを大きくする調整が可能となる。例えばパワーファクターを２以上とする場合、Px方向ではΔVEC=－0.3～－3程度、Pz方向ではΔVEC=0.3～4程度で制御できる。 FIG. 4 is a diagram showing the relationship between VEC and power factor of W 8 Sn 5 O 23 . As described above, a part of W or the like can be replaced with another element to control the positive / negative change amount ΔVEC of VEC. When VEC = 205 (ΔVEC = −1), adjustment to increase the power factor in the Px direction is possible as shown in FIG. When VEC = 207 (ΔVEC = 1), adjustment to increase the power factor in the Pz direction is possible as shown in FIG. For example, when the power factor is 2 or more, control can be performed with ΔVEC = −0.3 to −3 in the Px direction and ΔVEC = 0.3 to 4 in the Pz direction.
　なお、図４において、Pxは、面内方向（図１のc軸に垂直な方向）のパワーファクターを示し、Pzは、面直方向（図１のc軸方向）のパワーファクターを示す。このようなVEC制御は、上記の遷移金属元素の他にも、Zn、Sc、Ti、V、Cr、Mn、Fe、Co、Ni、Cuのような遷移金属元素を用いることができる。また、WをAl、Ga、In、Tl、Zr、Nb、Mo、Taに置き換えてもよい。 In FIG. 4, Px indicates the power factor in the in-plane direction (direction perpendicular to the c-axis in FIG. 1), and Pz indicates the power factor in the perpendicular direction (c-axis direction in FIG. 1). Such VEC control can use transition metal elements such as Zn, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu in addition to the above transition metal elements. Further, W may be replaced with Al, Ga, In, Tl, Zr, Nb, Mo, Ta.
　さらに、Wと同様にSnも元素置換することによって、VEC制御が可能である。Snと価電子数が異なるB、Al、Ga、In、N、O、P、As、Sb、Bi、Sなどの元素を用いることができる。また、母相であるWおよびSnよりも添加元素が多くなるとW8Sn5O23構造を保つことが難しくなるため、W(8-x)MxSn(5-y)TyO23-zのx、y、zは（0≦x≦2、0≦y≦2、0≦z≦2）の範囲であることが望ましい。 Furthermore, VEC can be controlled by substituting Sn as well as W. Elements such as B, Al, Ga, In, N, O, P, As, Sb, Bi, and S, which have a different valence electron number from Sn, can be used. In addition, since it becomes difficult to maintain the W 8 Sn 5 O 23 structure when there are more additive elements than the parent phases W and Sn, W (8-x) M x Sn (5-y) T y O 23- z of x, y, z is preferably in the range of (0 ≦ x ≦ 2,0 ≦ y ≦ 2,0 ≦ z ≦ 2).
　元素置換の効果として、上記のVEC制御の他に熱伝導率低減が可能となる。熱伝導率の低減は、母相であるW8Sn5O23の成分であるWおよびSnと原子量が異なる重元素や軽元素による置換が効果的である。そのため、Snより原子量の大きなSb、Bi、Baなどの元素にSnを置換することによって熱伝導率を低減可能となる。 As an effect of element substitution, thermal conductivity can be reduced in addition to the above VEC control. For reduction of thermal conductivity, substitution with heavy elements or light elements having an atomic weight different from W and Sn, which are components of W 8 Sn 5 O 23 as a parent phase, is effective. Therefore, the thermal conductivity can be reduced by substituting Sn with an element such as Sb, Bi, or Ba having an atomic weight larger than that of Sn.
　W8Sn5O23の結晶構造は六方晶であるため、異方的な性質を有している。図４に示すように、パワーファクターの値は方向によって値が異なっており、ΔVEC>0の場合はc軸方向のパワーファクター（Pz）の絶対値が高く、ΔVEC<0の場合c軸に垂直な方向のパワーファクター（Px）の絶対値が高くなる。従って、結晶方向の配向を制御することによって熱電変換特性をより大きくすることが可能となる。W8Sn5O23が主成分の場合、六方晶となる主成分の微結晶のc方向が配向しており、W8Sn5O23のc軸方向と温度勾配方向が平行の時には、n型熱電変換素子の性能を向上させることができる。また、そのc軸方向と温度勾配方向が垂直の時には、p型としての性能を増大させることが可能である。 Since the crystal structure of W 8 Sn 5 O 23 is hexagonal, it has anisotropic properties. As shown in FIG. 4, the power factor value varies depending on the direction. When ΔVEC> 0, the absolute value of the power factor (Pz) in the c-axis direction is high, and when ΔVEC <0, it is perpendicular to the c-axis. The absolute value of the power factor (Px) in any direction increases. Therefore, thermoelectric conversion characteristics can be further increased by controlling the orientation in the crystal direction. When W 8 Sn 5 O 23 is the main component, the c direction of the main crystal microcrystal that is hexagonal is oriented, and when the c axis direction of W 8 Sn 5 O 23 and the temperature gradient direction are parallel, n The performance of the type thermoelectric conversion element can be improved. Further, when the c-axis direction and the temperature gradient direction are perpendicular to each other, the performance as a p-type can be increased.
　＜３．単位原子当りの体積の検討＞
　なお、WおよびSnおよび酸素を主成分として、前記主成分の微結晶の組成がW(8-x)MxSn(5-y)TyO23-zとなる化合物（元素M、Tは、WおよびSnとは異なる元素）は様々な組み合わせが可能である。 <3. Examination of volume per unit atom>
A compound having W, Sn, and oxygen as main components and the composition of microcrystals of the main component is W (8-x) M x Sn (5-y) T y O 23-z (elements M and T are , Elements different from W and Sn) can be variously combined.
　図５には、選択可能な元素の価電子数と元素の対応表を示す。例えば、元素M、Tとして、図５の表に記載の元素から任意の元素を選択することが可能である。このとき、x、yは（0≦x＜2、0≦y＜2、-2≦z＜2）の範囲であることが望ましい。 FIG. 5 shows a correspondence table between selectable element valence electrons and elements. For example, as the elements M and T, any element can be selected from the elements described in the table of FIG. At this time, x and y are preferably in the range of (0 ≦ x <2, 0 ≦ y <2, −2 ≦ z <2).
　熱電変換素子における熱起電力は、物質の電子状態に依存し、高い熱起電力を得る観点から、フェルミレベル近傍の状態密度の変化が急峻な材料が良い。また、熱伝導率を低くするためには、結晶構造中に複数の元素及び重元素が含まれることが望ましい。上記した観点から、元素α、元素βを主成分として含むW8Sn5O23構造系において、例えば元素置換や元素ドープを行い、１原子当りの体積を所定の範囲に制御し、またキャリア密度を調整する。これにより、優れた熱電変換特性を実現できる。 The thermoelectromotive force in the thermoelectric conversion element depends on the electronic state of the substance. From the viewpoint of obtaining a high thermoelectromotive force, a material having a sharp change in state density near the Fermi level is preferable. In order to reduce the thermal conductivity, it is desirable that a plurality of elements and heavy elements are included in the crystal structure. From the above viewpoint, in the W 8 Sn 5 O 23 structure system containing the elements α and β as main components, for example, element substitution or element doping is performed, the volume per atom is controlled within a predetermined range, and the carrier density Adjust. Thereby, the outstanding thermoelectric conversion characteristic is realizable.
　ここで、１原子当りの体積は、各結晶格子の体積を、構成原子数で除した値である。 Here, the volume per atom is a value obtained by dividing the volume of each crystal lattice by the number of constituent atoms.
　例えば、格子定数がａ＝7.667Å、ｃ＝１８．６４ÅであるW8Sn5O23における１原子当りの体積ｖは、ｖ＝ａ×ａ√3/2×ｃ／７２＝１３．１８Å３となる。W8Sn5O23のWやSnの一部の元素置換によって格子定数を調整することができる。例えば、W8Sn5O23は、IV族元素であるSnの一部をGeで置換してW8Sn5-xGexO23とすることにより（０≦ｘ≦５）の結晶中の１原子当りの体積は、置換量ｘの値に応じて、１２．６０Å３～１３．１８Å３の範囲で変化するとともに、その物性が変化する。 For example, the volume v per atom in W 8 Sn 5 O 23 with lattice constants a = 7.667Å and c = 18.64Å is v = a × a√3 / 2 × c / 72 = 13.18７２ 3 It becomes. The lattice constant can be adjusted by substituting some elements of W and Sn in W 8 Sn 5 O 23 . For example, W 8 Sn 5 O 23, by substituting a part of Sn is Group IV element in Ge and W 8 Sn 5-x Ge x O 23 in the crystals (0 ≦ x ≦ 5) The volume per atom changes in the range of 12.60Å 3 to 13.18Å 3 according to the value of the substitution amount x, and the physical properties thereof change.
　図６は、結晶中の１原子当りの体積とパワーファクターの関係を示すグラフ図である。図６（Ａ）はN型で、Mo8Sn5O23のSn5をGe5に置換している（四角のプロット）。また、W8Sn5O23のSn5をGe5、Si5に置換している（丸のプロット）。図６（Ｂ）P型では、おなじくMo8Sn5O23のSn5を置換している（四角のプロット）。また、W8Sn5O23のSn5を置換している（丸のプロット）。図６では、Sn5を他の１つの元素に全て置換した点をプロットしているが、Sn5を２種類以上の元素で置換してもよいし、一部のみを置換してもよい。図６（Ａ）よりN型は結晶中の1原子当たりの体積が増加するとともにパワーファクターも増加しており、１３．２０Å３程度で最大となっている。一方、図６（Ｂ）より、P型は１２．５Å３程度で最大となっている。従って、P型N型ともに１２．４～１３．４０Å３の範囲において極めて優れた熱電変換を有する材料系に調整できる。図６のデータからは、１原子当りの体積とパワーファクターの間に有意な関係が認められる。N型では１２．４～１３．２Å３が、P型では１２．６～１３．２Å３程度が好ましいという結果が得られた。これは、１原子あたりの体積変化が、材料のバンド構造の変化を反映しているものと考えられる。 FIG. 6 is a graph showing the relationship between the volume per atom in the crystal and the power factor. FIG. 6 (A) was replaced with N-type, the Sn 5 of Mo 8 Sn 5 O 23 to Ge 5 (square plots). Also, by substituting Sn 5 of W 8 Sn 5 O 23 to Ge 5, Si 5 (plot circles). In FIG. 6 (B) P-type, and replacing the Sn 5 effective image Mo 8 Sn 5 O 23 (square plots). Also, by substituting Sn 5 of W 8 Sn 5 O 23 (plot circles). In Figure 6, but plotted points was replaced all Sn 5 to one other element, may be substituted Sn 5 at two or more elements may be partially replaced only. N-type from FIG 6 (A) is the power factor with a volume per atom in the crystal is increased also increased, and has a maximum at about 13.20Å 3. On the other hand, from FIG. 6 (B), the P type is the maximum at about 12.5 cm 3 . Therefore, both P-type and N-type materials can be adjusted to a material system having extremely excellent thermoelectric conversion in the range of 12.4 to 13.40 cm 3 . From the data in FIG. 6, a significant relationship is recognized between the volume per atom and the power factor. The N-type 12.4 ~ 13.2Å 3, results in preferably about 12.6 ~ 13.2Å 3 is P-type was obtained. This is considered that the volume change per atom reflects the change in the band structure of the material.
　本発明の実施例による熱電変換材料の結晶構造は、X線回折(XRD)によって容易に確認ができる。また、TEM（Transmission Electron Miroscop）などの電子顕微鏡により格子像を観察することや電子線回折像においてスポット状パターンやリング状パターンから単結晶もしくは多結晶の結晶構造を確認することができる。組成分布はEDX（Energy Dispersive X-ray spectroscopy）などのEPMA （Electron Probe MicroAnalyser）や、SIMS(Secondary Ionization Mass Spectrometer)、X線光電子分光、ICP（Inductively Coupled Plasma）ななどの手法を用いて確認できる。また、材料の状態密度の情報に関しては、紫外線光電子分光法やX線光電子分光などによって確認できる。電気伝導率およびキャリア密度は4端子法を用いた電気測定およびホール効果測定によって確認できる。ゼーベック係数は、試料両端に温度差をつけ、両端の電圧差を測定することによって確認できる。熱伝導率はレーザーフラッシュ法によって確認できる。 The crystal structure of the thermoelectric conversion material according to the example of the present invention can be easily confirmed by X-ray diffraction (XRD). In addition, a lattice image can be observed with an electron microscope such as TEM (TransmissionTransElectron Miroscop) or a single crystal or polycrystal structure can be confirmed from a spot pattern or ring pattern in an electron beam diffraction image. Composition distribution can be confirmed using EPMA (Electron Probe Probe MicroAnalyser) such as EDX (Energy Dispersive X-ray Spectroscopy), SIMS (Secondary Ionization Mass Mass Spectrometer), X-ray photoelectron spectroscopy, ICP (Inductively Coupled Plasma), etc. . Information on the state density of the material can be confirmed by ultraviolet photoelectron spectroscopy or X-ray photoelectron spectroscopy. The electrical conductivity and carrier density can be confirmed by electrical measurement using the four-terminal method and Hall effect measurement. The Seebeck coefficient can be confirmed by giving a temperature difference to both ends of the sample and measuring the voltage difference between both ends. The thermal conductivity can be confirmed by a laser flash method.
　図７には、本発明の実施例であるWSnO系材料をX線回折により分析した結果を示す。上記検討により構成された組成を反映した結果が得られている。 FIG. 7 shows the result of analyzing the WSnO material which is an example of the present invention by X-ray diffraction. The result reflecting the composition constituted by the above examination is obtained.
　＜４．製造方法と測定の例＞
　以下、本発明の実施例を用いた試料作製の一例を示す。ここで作製例は一例であって、当該作製条件に限定されるものではない。 <4. Example of manufacturing method and measurement>
Hereinafter, an example of sample preparation using an embodiment of the present invention will be shown. Here, the manufacturing example is an example, and the manufacturing conditions are not limited thereto.
　(試料作製例１)
　純度99.9％のWO2粉末と99.99％のSnO2と99.99％のSn粉末およびSb粉末を16:7:2.9:0.1の組成比となる割合で混合し、メカニカルアロイング法により、合金を作製した後、作製した材料の組成からVECを計算すると206.05となる。 (Sample preparation example 1)
A 99.9% pure WO 2 powder, 99.99% SnO 2 and 99.99% Sn powder and Sb powder were mixed at a composition ratio of 16: 7: 2.9: 0.1, and an alloy was produced by mechanical alloying. Later, when VEC is calculated from the composition of the produced material, 206.05 is obtained.
　(試料作製例２)
　純度99.9％のWO2粉末と99.99のSnO2と99.99のSn粉末およびを16:7:3の組成比となる割合で混合し、石英管に入れ、真空雰囲気におい1000℃で24時間熱処理を行い、その後、ボールミルを用いて試料を粉砕した。その粉末試料のX線回折を行って構造解析した結果、W8Sn5O23構造由来の結晶構造ピークが観測できる。 (Sample preparation example 2)
99.9% pure WO 2 powder, 99.99 SnO 2 and 99.99 Sn powder were mixed at a composition ratio of 16: 7: 3, placed in a quartz tube, and heat-treated at 1000 ° C. for 24 hours in a vacuum atmosphere. Thereafter, the sample was pulverized using a ball mill. As a result of X-ray diffraction analysis of the powder sample, a crystal structure peak derived from the W 8 Sn 5 O 23 structure can be observed.
　(試料作製例３)
　純度99.9％のWO2粉末、純度99.9％のMoO2粉末、99.99％のSnO2と99.99％のSn粉末を15:1:7:3の組成比となる割合で混合し、石英管に入れ、真空雰囲気におい700℃で24時間熱処理を行い、その後、ボールミルを用いて試料を粉砕した。その粉末試料のX線回折を行って構造解析した結果、W8Sn5O23構造であった。W7.5Mo0.5Sn5O23の粉末試料からVECを計算すると206.0となる。 (Sample preparation example 3)
99.9% purity WO 2 powder, 99.9% purity MoO 2 powder, 99.99% SnO 2 and 99.99% Sn powder were mixed in a ratio of 15: 1: 7: 3 and put into a quartz tube. Heat treatment was performed in a vacuum atmosphere at 700 ° C. for 24 hours, and then the sample was pulverized using a ball mill. As a result of X-ray diffraction analysis of the powder sample, it was a W 8 Sn 5 O 23 structure. When VEC is calculated from a powder sample of W 7.5 Mo 0.5 Sn 5 O 23 , it is 206.0.
　(試料作製例４)
　試料作製例３と同様の方法で、Wを一部Mo、Cr、Ti、Taに置き換えW6Mo2Sn5O23、W7CrSn5O23、W7.9Ti0.1Sn5O23、W7.9Ta0.1Sn5O23を作製した。 (Sample preparation example 4)
W 6 Mo 2 Sn 5 O 23 , W 7 CrSn 5 O 23 , W 7.9 Ti 0.1 Sn 5 O 23 , W 7.9 In the same manner as in Sample Preparation Example 3, W is partially replaced with Mo, Cr, Ti, Ta. Ta 0.1 Sn 5 O 23 was produced.
　(試料作製例５)
　純度99.9％のWO2粉末、純度99.9％のMoO2粉末、99.99％のSnO2、99.99％のSn粉末と99.99％のGe粉末を15:1:7:2:1の組成比となる割合で混合し、石英管に入れ、真空雰囲気におい700℃で24時間熱処理を行い、その後、ボールミルを用いて試料を粉砕した。その粉末試料のX線回折を行って構造解析した結果、W8Sn5O23構造であった。W8 Sn3.33Ge1.67O23の粉末試料からVECを計算すると206.0となる。 (Sample preparation example 5)
99.9% pure WO 2 powder, 99.9% pure MoO 2 powder, 99.99% SnO 2 , 99.99% Sn powder and 99.99% Ge powder in a ratio of 15: 1: 7: 2: 1 The mixture was mixed, put into a quartz tube, heat-treated in a vacuum atmosphere at 700 ° C. for 24 hours, and then the sample was pulverized using a ball mill. As a result of X-ray diffraction analysis of the powder sample, it was a W 8 Sn 5 O 23 structure. When VEC is calculated from a powder sample of W 8 Sn 3.33 Ge 1.67 O 23 , it is 206.0.
　(試料作製例６)
　熱酸化膜を有するSi基板に、W8Sn5O23ターゲットを用いて、スパッタリングすることにより300nm程度の膜厚の薄膜を作製し、窒素雰囲気中で1000℃の条件で、1時間熱処理を行った。薄膜のX線回折を行って構造解析した結果、W8Sn5O23構造のピークが観測できた。 (Sample preparation example 6)
Using a W 8 Sn 5 O 23 target, a thin film with a film thickness of about 300 nm is fabricated on a Si substrate with a thermal oxide film, and heat treatment is performed in a nitrogen atmosphere at 1000 ° C. for 1 hour. It was. As a result of X-ray diffraction analysis of the thin film, a peak of the W 8 Sn 5 O 23 structure was observed.
　(試料測定例１)
　試料作製例１と試料作製例２で作製した試料に室温と20℃の温度差を作り、ゼーベック係数を測定した。その結果、それぞれ-250Vμ/K、250μV/Kの高いゼーベック係数を得た。従って本実施例によってドーピング量によってVECを変化させ、ゼーベック係数を変調でき、p型とおよびｎ型として高い熱起電力を有する材料系であることを確認した。また、熱伝導率はそれぞれ1.0W/Km、0.9W/Kmであった。 (Sample measurement example 1)
A temperature difference between room temperature and 20 ° C. was made on the samples prepared in Sample Preparation Example 1 and Sample Preparation Example 2, and the Seebeck coefficient was measured. As a result, high Seebeck coefficients of −250 Vμ / K and 250 μV / K were obtained, respectively. Therefore, according to this example, it was confirmed that the VEC was changed depending on the doping amount, the Seebeck coefficient could be modulated, and the material system had a high thermoelectromotive force as p-type and n-type. The thermal conductivities were 1.0 W / Km and 0.9 W / Km, respectively.
　試料作製方法は、本実施例以外の分子線エピタキシーのような真空蒸着法でも、化学気相成長を用いても良い。粉末材料の焼結方法としては、放電プラズマ焼結法やホットプレス法、ホットフォージ法などを用いても良い。 The sample preparation method may be a vacuum evaporation method such as molecular beam epitaxy other than the present embodiment, or chemical vapor deposition. As a method for sintering the powder material, a discharge plasma sintering method, a hot press method, a hot forge method, or the like may be used.
　上記本実施例によれば、ドーピングによる価電子数の違う元素の添加し、化合物の価電子数を制御することにより、バンドの電子占有数を変化させ、フェルミレベルにおける電子状態を変調し、高い熱起電力を実現できる。また、安価で枯渇の懸念が少ない材料を組み合わせることによって、低コストで無毒な熱電変換材料の作製が可能となる。 According to the present embodiment, by adding an element having a different valence number by doping and controlling the number of valence electrons of the compound, the number of electrons occupied by the band is changed, the electronic state at the Fermi level is modulated, and high Thermoelectromotive force can be realized. In addition, by combining materials that are inexpensive and less likely to be depleted, it is possible to produce a low-cost and non-toxic thermoelectric conversion material.
　＜５．熱電変換素子、装置の構成例＞
　図８に、上記実施例で説明した材料を熱電変換素子１００に用いた例を示す。１０４は上記実施例で説明した熱電変換材料、１０２ａは熱電変換材料１０４に電気的に接触する高温側電極、１０２ｂは熱電変換材料１０４に電気的に接触する低温側電極、１２０，１３０は電流経路を示す（熱電変換材料１０４がP型かN型かで，電流方向が異なる）。 <5. Configuration example of thermoelectric conversion element and device>
FIG. 8 shows an example in which the material described in the above embodiment is used for the thermoelectric conversion element 100. 104 is the thermoelectric conversion material described in the above embodiment, 102a is a high temperature side electrode that is in electrical contact with the thermoelectric conversion material 104, 102b is a low temperature side electrode that is in electrical contact with the thermoelectric conversion material 104, and 120 and 130 are current paths. (The current direction is different depending on whether the thermoelectric conversion material 104 is P-type or N-type).
　図９に、上記実施例で説明した材料を熱電変換素子２００に用いた他の例を示す。１０３、１０４は上記実施例で説明した熱電変換材料であり、P型（１０３）とN型（１０４）を両方用いている。１０２ｃは熱電変換材料１０４に電気的に接触する高温側電極、１０２ｂ，１０２ｄは熱電変換材料１０４に電気的に接触する低温側電極、１４０は電流経路を示す。 FIG. 9 shows another example in which the material described in the above embodiment is used for the thermoelectric conversion element 200. 103 and 104 are the thermoelectric conversion materials described in the above embodiments, and both P-type (103) and N-type (104) are used. Reference numeral 102c denotes a high temperature side electrode in electrical contact with the thermoelectric conversion material 104, reference numerals 102b and 102d denote low temperature side electrodes in electrical contact with the thermoelectric conversion material 104, and reference numeral 140 denotes a current path.
　図１０に、図９に示した熱電変換素子２００を複数直列接続して構成した、熱電変換モジュール３００の斜視図を示す。筐体１０１の上部を一部切り欠いて、内部が見えるようにしている。筐体１０１は熱を熱電変換素子２００に伝える役割も果たす。熱電変換素子２００は、上部または下部電極１０２で筐体１０１と接触している。 FIG. 10 shows a perspective view of a thermoelectric conversion module 300 configured by connecting a plurality of thermoelectric conversion elements 200 shown in FIG. 9 in series. A part of the upper portion of the housing 101 is cut away so that the inside can be seen. The housing 101 also plays a role of transferring heat to the thermoelectric conversion element 200. The thermoelectric conversion element 200 is in contact with the housing 101 at the upper or lower electrode 102.
　本発明は上記した実施形態に限定されるものではなく、様々な変形例が含まれる。例えば、ある実施例の構成の一部を他の実施例の構成に置き換えることが可能であり、また、ある実施例の構成に他の実施例の構成を加えることが可能である。また、各実施例の構成の一部について、他の実施例の構成の追加・削除・置換をすることが可能である。 The present invention is not limited to the above-described embodiment, and includes various modifications. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace the configurations of other embodiments with respect to a part of the configurations of the embodiments.
　熱エネルギーから電力を得る電変換材料、熱電変換素子、及びそれを用いた熱電変換モジュールの分野に適用可能である。 It can be applied to the fields of electric conversion materials that obtain electric power from thermal energy, thermoelectric conversion elements, and thermoelectric conversion modules using the same.
１００：熱電変換素子
１０２ａ：高温側電極
１０２ｂ：低温側電極
１０３：P型熱電変換材料
１０４：N型熱電変換材料 100: Thermoelectric conversion element 102a: High temperature side electrode 102b: Low temperature side electrode 103: P-type thermoelectric conversion material 104: N-type thermoelectric conversion material

Claims (15)

  1. 　W、Mo及びCrからなる群から選ばれる少なくとも一種以上の元素αと、Si、Ge、Sn及びCからなる群から選ばれる少なくとも一種以上の元素βと、酸素を含み、
    　空間群P 63/mの六方晶構造を有しており、
    　１原子当りの体積Ｖが１２．４≦Ｖ≦１３．４Å３であることを特徴とする熱電変換材料。     At least one element α selected from the group consisting of W, Mo and Cr, at least one element β selected from the group consisting of Si, Ge, Sn and C, and oxygen,
    It has a hexagonal structure with space group P 6 3 / m,
    Thermoelectric conversion material, wherein the volume V per atom is 12.4 ≦ V ≦ 13.4Å 3.
  2. 　前記六方晶構造はW8Sn5O23構造であり、
    　前記元素αであるWの一部又は全部が、Mo及びCrからなる群から選ばれる少なくとも一種で置換されるか、
    　前記元素βであるSnの一部又は全部が、Si、Ge、及びCからなる群から選ばれる少なくとも一種で置換されていることを特徴とする、
    　請求項1記載の熱電変換材料。     The hexagonal structure is a W 8 Sn 5 O 23 structure,
    Part or all of W as the element α is substituted with at least one selected from the group consisting of Mo and Cr,
    Part or all of Sn as the element β is substituted with at least one selected from the group consisting of Si, Ge, and C,
    2. The thermoelectric conversion material according to claim 1.
  3. 　V、Ti、Zr、Al、Ga、In、Li、Na、Ca、Li、Na及びKからなる群から選ばれる少なくとも一種が添加され、p型熱電変換材料を構成することを特徴とする、
    　請求項1記載の熱電変換材料。     At least one selected from the group consisting of V, Ti, Zr, Al, Ga, In, Li, Na, Ca, Li, Na and K is added, and constitutes a p-type thermoelectric conversion material,
    2. The thermoelectric conversion material according to claim 1.
  4. 　Cu、Ag、Fe、Mn、Co、Ni、P、As、Sb、Biからなる群から選ばれる少なくとも一種が添加され、n型熱電変換材料を構成することを特徴とする、
    　請求項1記載の熱電変換材料。     At least one selected from the group consisting of Cu, Ag, Fe, Mn, Co, Ni, P, As, Sb, Bi is added, and constitutes an n-type thermoelectric conversion material,
    2. The thermoelectric conversion material according to claim 1.
  5. 　キャリア密度が１×１０１９～１×１０２１ｃｍ－３の範囲であることを特徴とする、
    　請求項1記載の熱電変換材料。     The carrier density is in the range of 1 × 10 19 to 1 × 10 21 cm −3 ,
    2. The thermoelectric conversion material according to claim 1.
  6. 　熱電変換材料部材と、
    　前記熱電変換材料部材に電気的に接触する第1の電極と、
    　前記熱電変換材料部材に電気的に接触する第２の電極と、
    　を備え、前記熱電変換材料部材に与えられる温度勾配により、前記第1の電極と前記第2の電極の間に電流を生ぜしめる熱電変換素子であって、
    　前記熱電変換材料部材は、
    　W、Mo及びCrからなる群から選ばれる少なくとも一種以上の元素αと、Si、Ge、Sn及びCからなる群から選ばれる少なくとも一種以上の元素βと、酸素を含み、空間群P 63/mの六方晶構造を有しており、１原子当りの体積Ｖが１２．４≦Ｖ≦１３．４Å３である熱電変換材料、により構成される、熱電変換素子。     A thermoelectric conversion material member;
    A first electrode in electrical contact with the thermoelectric conversion material member;
    A second electrode in electrical contact with the thermoelectric conversion material member;
    A thermoelectric conversion element that generates a current between the first electrode and the second electrode due to a temperature gradient applied to the thermoelectric conversion material member,
    The thermoelectric conversion material member is
    At least one element α selected from the group consisting of W, Mo and Cr, at least one element β selected from the group consisting of Si, Ge, Sn and C, and oxygen, and a space group P 6 3 / has a hexagonal structure of m, the thermoelectric conversion material volume V per atom is 12.4 ≦ V ≦ 13.4Å 3, the constructed, the thermoelectric conversion element.
  7. 　前記六方晶構造はW8Sn5O23構造であり、
    　前記元素αであるWの一部又は全部が、Mo及びCrからなる群から選ばれる少なくとも一種で置換されるか、
    　前記元素βであるSnの一部又は全部が、Si、Ge、及びCからなる群から選ばれる少なくとも一種で置換されていることを特徴とする、
    　請求項６記載の熱電変換素子。     The hexagonal structure is a W 8 Sn 5 O 23 structure,
    Part or all of W as the element α is substituted with at least one selected from the group consisting of Mo and Cr,
    Part or all of Sn as the element β is substituted with at least one selected from the group consisting of Si, Ge, and C,
    The thermoelectric conversion element according to claim 6.
  8. 　前記W8Sn5O23構造に、
    　W、Mo、Cr、Sn、Si、Ge、及びCとは異なる元素A,Bを導入したW8(1-x)B8xSn5(1-y)B5yO23-zを用いることによって、価電子数密度（VEC）を制御したことを特徴とする、
    　請求項７記載の熱電変換素子。     In the W 8 Sn 5 O 23 structure,
    By using W 8 (1-x) B 8x Sn 5 (1-y) B 5y O 23-z introduced with elements A and B different from W, Mo, Cr, Sn, Si, Ge, and C , Characterized by controlled valence number density (VEC),
    The thermoelectric conversion element according to claim 7.
  9. 　前記熱電変換材料は、前記αとβの原子パーセントの比率が、３：２～４：３であることを特徴とする、
    　請求項６記載の熱電変換素子。     The thermoelectric conversion material is characterized in that the ratio of atomic percent of α and β is 3: 2 to 4: 3.
    The thermoelectric conversion element according to claim 6.
  10. 　前記熱電変換材料は、キャリア密度が１×１０１９～１×１０２１ｃｍ－３の範囲であることを特徴とする、
    　請求項６記載の熱電変換素子。     The thermoelectric conversion material has a carrier density in the range of 1 × 10 19 to 1 × 10 21 cm −3 ,
    The thermoelectric conversion element according to claim 6.
  11. 　前記六方晶構造となる主成分の微結晶のc方向が配向しており、
    　その配向方向と温度勾配方向とが平行であるように配置されることを特徴とする、
    　請求項６記載の熱電変換素子。     The c direction of the main crystallites having the hexagonal structure is oriented,
    The orientation direction and the temperature gradient direction are arranged so as to be parallel,
    The thermoelectric conversion element according to claim 6.
  12. 　前記六方晶構造となる主成分の微結晶のc方向が配向しており、
    　その配向方向と温度勾配方向とが垂直であるように配置されることを特徴とする、
    　請求項６記載の熱電変換素子。     The c direction of the main crystallites having the hexagonal structure is oriented,
    The orientation direction and the temperature gradient direction are arranged so as to be perpendicular,
    The thermoelectric conversion element according to claim 6.
  13. 　熱電変換素子を複数備える熱電変換モジュールであって、
    　前記熱電変換素子は、
    　熱電変換材料部材と、前記熱電変換材料部材に電気的に接触する第1の電極と、前記熱電変換材料部材に電気的に接触する第２の電極と、を備え、前記熱電変換材料部材に与えられる温度勾配により、前記第１の電極と前記第２の電極の間に電流を生ぜしめ、
    　前記熱電変換材料部材は、
    　W、Mo及びCrからなる群から選ばれる少なくとも一種以上の元素αと、Si、Ge、Sn及びCからなる群から選ばれる少なくとも一種以上の元素βと、酸素を含み、空間群P 63/mの六方晶構造を有しており、１原子当りの体積Ｖが１２．４≦Ｖ≦１３．４Å３であることを特徴とする熱電変換材料で構成され、
    　前記複数の熱電変換素子は、前記熱電変換材料部材がp型である第１の素子と、前記熱電変換材料部材がn型である第２の素子を含み、
    　前記第１の電極は前記熱電変換材料部材の比較的高温側に配置され、前記第２の電極は前記熱電変換材料部材の比較的低温側に配置され、
    　前記第１の素子の第１の電極と、前記第２の素子の第１の電極とが、直列接続され、
    　前記第１の素子の第２の電極と、前記第２の素子の第２の電極とが、直列接続され、
    　て構成される熱電変換モジュール。     A thermoelectric conversion module comprising a plurality of thermoelectric conversion elements,
    The thermoelectric conversion element is
    A thermoelectric conversion material member; a first electrode in electrical contact with the thermoelectric conversion material member; and a second electrode in electrical contact with the thermoelectric conversion material member; The resulting temperature gradient causes a current to flow between the first electrode and the second electrode;
    The thermoelectric conversion material member is
    At least one element α selected from the group consisting of W, Mo and Cr, at least one element β selected from the group consisting of Si, Ge, Sn and C, and oxygen, and a space group P 6 3 / has a hexagonal structure of m, is composed of a thermoelectric conversion material, wherein the volume V per atom is 12.4 ≦ V ≦ 13.4Å 3,
    The plurality of thermoelectric conversion elements include a first element in which the thermoelectric conversion material member is p-type, and a second element in which the thermoelectric conversion material member is n-type,
    The first electrode is disposed on a relatively high temperature side of the thermoelectric conversion material member, and the second electrode is disposed on a relatively low temperature side of the thermoelectric conversion material member,
    The first electrode of the first element and the first electrode of the second element are connected in series,
    The second electrode of the first element and the second electrode of the second element are connected in series,
    A thermoelectric conversion module configured.
  14. 　前記第１の素子の熱電変換材料部材は、
    　V、Ti、Zr、Al、Ga、In、Li、Na、Ca、Li、Na及びKからなる群から選ばれる少なくとも一種が添加され、p型熱電変換材料で構成されることを特徴とする、
    　請求項１３記載の熱電変換モジュール。     The thermoelectric conversion material member of the first element is
    At least one selected from the group consisting of V, Ti, Zr, Al, Ga, In, Li, Na, Ca, Li, Na, and K is added, and the p-type thermoelectric conversion material is used.
    The thermoelectric conversion module according to claim 13.
  15. 　前記第２の素子の熱電変換材料部材は、
    　Cu、Ag、Fe、Mn、Co、Ni、P、As、Sb、Biからなる群から選ばれる少なくとも一種が添加され、n型熱電変換材料で構成されることを特徴とする、
    　請求項１３記載の熱電変換モジュール。     The thermoelectric conversion material member of the second element is
    At least one selected from the group consisting of Cu, Ag, Fe, Mn, Co, Ni, P, As, Sb, Bi is added, and is composed of an n-type thermoelectric conversion material,
    The thermoelectric conversion module according to claim 13.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020047811A (en) * 2018-09-20 2020-03-26 株式会社東芝 Semiconductor device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006096656A (en) * 2004-08-31 2006-04-13 Sumitomo Metal Mining Co Ltd Transparent conductive film and its manufacturing method, transparent conductive article, and infrared shielding article
WO2006103871A1 (en) * 2005-03-25 2006-10-05 Asahi Glass Company, Limited Electrically conductive material
JP2011198518A (en) * 2010-03-17 2011-10-06 Tohoku Univ Conductive particulate and method for manufacturing the same, and visible light transmission type particle dispersion conductor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006096656A (en) * 2004-08-31 2006-04-13 Sumitomo Metal Mining Co Ltd Transparent conductive film and its manufacturing method, transparent conductive article, and infrared shielding article
WO2006103871A1 (en) * 2005-03-25 2006-10-05 Asahi Glass Company, Limited Electrically conductive material
JP2011198518A (en) * 2010-03-17 2011-10-06 Tohoku Univ Conductive particulate and method for manufacturing the same, and visible light transmission type particle dispersion conductor

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
GOREAUD, M. ET AL.: "A mixed-valance tungsten oxide of divalent tin : Sn10W16O46 I.Structure determination, Acta Crystallographica", SECTION B: STRUCTURAL CRYSTALLOGRAPHY AND CRYSTAL CHEMISTRY, vol. 36, no. 1, 1980, pages 15 - 19, XP055330886 *
GOREAUD, M. ET AL.: "A mixed-valance tungsten oxide of divalent tin : Sn10W16O46 II. Analysis of the structure and stereoactivity of the tin(II) lone pair", ACTA CRYSTALLOGRAPHICA, SECTION B: STRUCTURAL CRYSTALLOGRAPHY AND CRYSTAL CHEMISTRY, vol. 36, no. 1, 1980, pages 19 - 22 *
HIBBLE, SIMON J. ET AL.: "Structure refinement from powder neutron diffraction data of Sn10W16O44, which contains a metal-metal bonded W6012 cluster", JOURNAL OF THE CHEMICAL SOCIETY, DALTON TRANSACTIONS : INORGANIC CHEMISTRY, vol. 12, 1995, pages 1947 - 1949 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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