Thermoelectric conversion element and method for manufacturing the same

Abstract

To provide a thermoelectric element in which a conductive layer is placed next to a thermoelectric material containing magnesium, antimony, etc., and that has sufficiently low resistance at these interfaces.SOLUTION: A thermoelectric element includes a thermoelectric material portion containing magnesium and antimony and / or bismuth, a conductive layer disposed adjacent to the thermoelectric material portion, containing at least one element selected from the group consisting of transition metals, zinc, aluminum, and silicon, and having a thickness of 5 μm or more and 100 μm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a thermoelectric conversion element and a method for manufacturing the same.

Background Art

[0002] In recent years, the development of clean and sustainable energy conversion technologies has attracted great attention from both the academic and industrial communities. Among them, thermoelectric conversion elements that recover waste heat or natural heat and convert it into electrical energy have drawn attention. In a thermoelectric conversion element, an electromotive force is generated by setting one surface of the element at a high temperature and the other surface at a low temperature. In such a thermoelectric conversion element, an N-type thermoelectric material part containing an N-type semiconductor material and a P-type thermoelectric material part containing a P-type semiconductor material are usually connected in series via electrodes.

[0003] Conventionally, as a semiconductor material (hereinafter also referred to as "thermoelectric material") that can be used for the thermoelectric material part of the thermoelectric conversion element, bismuth-tellurium-based materials are known, and thermoelectric conversion elements using bismuth-tellurium-based thermoelectric materials have already been put into practical use. On the other hand, many high-performance thermoelectric materials other than bismuth-tellurium-based materials have also been developed in recent years. For example, thermoelectric materials containing magnesium and antimony and / or bismuth such as Mg3Sb2 have been developed (see Non-Patent Documents 1 and 2), and these are expected to be high-performance thermoelectric materials because they can generate an electromotive force even at about 500°C.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

[0005] As mentioned above, when using thermoelectric materials in thermoelectric conversion elements, it is necessary to connect the thermoelectric material to electrodes, etc., and the resistance at these junction interfaces must be low. However, thermoelectric materials containing Mg3Sb2 tend to have high resistance at the interfaces with adjacent layers. Furthermore, as described in Non-Patent Document 2 above, these interfacial resistances can be reduced by integral sintering the thermoelectric material containing Mg3Sb2 with the material of the adjacent layer, but integral sintering is not suitable for mass production. In addition, layers produced by integral sintering tend to be thick. Therefore, thermoelectric conversion elements using this thermoelectric material are currently difficult to commercialize.

[0006] The reason why the interfacial resistance between the thermoelectric material (such as Mg3Sb2) and the adjacent layer is high is thought to be as follows: In thermoelectric materials such as Mg3Sb2, the magnesium in the material readily reacts with water and other solvents. Therefore, when a layer is formed on the thermoelectric material using a solvent-based film deposition method such as wet plating, the thermoelectric conversion material deteriorates, which is thought to increase the resistance. In addition, an oxide film easily forms on the surface of the thermoelectric material, and it is thought that this oxide film cannot be removed by general film deposition methods, which is also a contributing factor.

[0007] Therefore, the present invention aims to provide a thermoelectric conversion element in which a conductive layer is disposed next to a thermoelectric material portion containing magnesium, antimony, etc., and in which the resistance value at the interface between these is sufficiently low, and to provide a method for easily manufacturing the thermoelectric conversion element. [Means for solving the problem]

[0008] In other words, the present invention provides a thermoelectric conversion element comprising a thermoelectric material portion containing magnesium and antimony and / or bismuth, and a conductive layer disposed adjacent to the thermoelectric material portion, the conductive layer containing at least one element selected from the group consisting of transition metals, zinc, aluminum, and silicon, and having a thickness of 5 μm to 100 μm.

[0009] Furthermore, the present invention provides a method for manufacturing a thermoelectric conversion element, comprising the steps of: preparing a thermoelectric material portion containing magnesium and antimony and / or bismuth; and thermal spraying the thermoelectric material portion with a material containing at least one element selected from the group consisting of transition metals, zinc, aluminum, and silicon to form a conductive layer. [Effects of the Invention]

[0010] The thermoelectric element of the present invention makes it possible to sufficiently reduce the resistance value at the interface between the thermoelectric material portion containing magnesium or antimony and the adjacent conductive layer. Furthermore, the method for manufacturing such a thermoelectric element of the present invention allows for the simple production of such an element. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1A is a plan view of a thermoelectric conversion element according to one embodiment of the present invention, and Figure 1B is a cross-sectional view taken along line AA in Figure 1A. [Figure 2] Figure 2A is a plan view of a thermoelectric conversion element according to a modified example of the present invention, and Figure 2B is a cross-sectional view taken along line AA in Figure 2A. [Figure 3] This is an SEM image of a thermoelectric conversion element in Example 1, in which Ni was bonded to a sintered body of Mg3Y0.02Sb1.5Bi0.5 by thermal spraying, and Cu blocks were bonded to both sides using Ag paste. [Figure 4] This is an EDS mapping image of the thermoelectric conversion element fabricated in Example 1. [Figure 5]This shows the electrical resistance distribution of the thermoelectric element of the thermoelectric conversion element fabricated in Example 1. [Figure 6] This is a photograph of the surface of the conductive layer of the thermoelectric conversion element fabricated in Example 1, observed with a scanning electron microscope. [Modes for carrying out the invention]

[0012] In this specification, a numerical range indicated by "~" means a numerical range that includes the numbers written before and after "~".

[0013] 1. Thermoelectric conversion element The thermoelectric conversion element of the present invention will now be described. The thermoelectric conversion element of the present invention comprises a thermoelectric material portion comprising a thermoelectric material comprising magnesium and antimony and / or bismuth, and a conductive layer having a thickness of 5 μm to 100 μm and containing a predetermined element, which is disposed adjacent to the thermoelectric material portion. As described above, conventionally, it has been difficult to lower the interfacial resistance between the thermoelectric material portion and the adjacent layer (conductive layer in the present invention). In contrast, the inventors have found that the interfacial resistance between the thermoelectric material portion and the conductive layer can be lowered by forming a conductive layer on the surface of the thermoelectric material portion by thermal spraying.

[0014] Thermal spraying is a method of melting and softening metal or ceramic particles by heating and spraying them onto a desired substance (in this case, the thermoelectric material). The sprayed particles cool and solidify instantly, forming a film. The reason why forming a conductive layer by thermal spraying, as in the present invention, lowers the interfacial resistance between the thermoelectric material and the conductive layer is thought to be as follows: As mentioned above, an oxide film layer is often formed on the surface of the thermoelectric material. In contrast, when a semi-liquid or liquid component is sprayed at a constant speed by thermal spraying, the oxide film present on the surface of the thermoelectric material is removed by material collision. Also, when molten and softened particles are sprayed, the surface of the thermoelectric material is easily covered evenly, forming a dense film. Furthermore, since thermal spraying does not require the use of solvents such as water, the thermoelectric material is less likely to deteriorate, which is also considered a contributing factor.

[0015] Furthermore, it is difficult to form a conductive layer with a thickness of 5 μm or more using general plating methods. On the other hand, it is difficult to form a layer of 100 μm or less using integral firing. Therefore, thermal spraying is suitable for forming a conductive layer with a thickness of 5 μm to 100 μm.

[0016] Figures 1A and 1B show a thermoelectric conversion element 100 according to one embodiment of the present invention. Figure 1A is a plan view of the thermoelectric conversion element 100, and Figure 1B is a cross-sectional view taken along line AA in Figure 1A. The thermoelectric conversion element 100 includes a thermoelectric material portion 110, two conductive layers 120 arranged adjacent to the thermoelectric material portion 110, two connecting layers 130 arranged adjacent to the conductive layers 120, a first electrode 140 and a second electrode 150 arranged adjacent to these, and a substrate 160 arranged on the side of the second electrode 150. The dotted lines in Figure 1A indicate the positions of the P-type thermoelectric material portion 110P and the N-type thermoelectric material portion 110N. The layers of the thermoelectric conversion element 100 will be described below, but the structure of the thermoelectric conversion element 100 of the present invention is not limited to this structure.

[0017] (Thermoelectric Materials Department) The thermoelectric material section 110 is a component for generating electromotive force and consists of two types: a P-type thermoelectric material section 110P and an N-type thermoelectric material section 110N. As shown in Figure 1A, the P-type thermoelectric material section 110P and the N-type thermoelectric material section 110N are arranged alternately and in a grid pattern when viewed from above. Furthermore, the P-type thermoelectric material section 110P and the N-type thermoelectric material section 110N are electrically connected in series via the first electrode 140 and the second electrode 150.

[0018] In this embodiment, either the P-type thermoelectric material section 110P or the N-type thermoelectric material section 110N may contain magnesium and antimony and / or bismuth, or both may contain magnesium and antimony and / or bismuth.

[0019] Examples of materials constituting the N-type thermoelectric material section 110N include (Mg,Y)3(Sb,Bi)2, Mg3(Sb,Bi,Te)2, Mg3(Sb,Bi,Se)2, Mg3(Sb,Bi,S)2, (Mg,La)3(Sb,Bi)2, (Mg,Sc)3(Sb,Bi)2, etc. Among these, (Mg,Y)3(Sb,Bi)2 and Mg3(Sb,Bi,Te)2 are particularly preferred because they generate electromotive force even at relatively low temperatures. In this specification, (Mg,Y) indicates elemental Mg, elemental Y, or a combination of Mg and Y. The same applies to other materials. Also, (Mg,Y)3(Sb,Bi)2 indicates (Mg,Y) 3+α (Sb,Bi) 2+β This includes materials where -0.1 ≤ α ≤ 0.5 and -0.1 ≤ β ≤ 0.1. The same applies to other materials. Generally, the composition ratios of these materials may vary slightly, but for convenience, they are expressed as integers as described above.

[0020] On the other hand, examples of thermoelectric materials constituting the P-type thermoelectric material section 110P include MgAgSb, (Mg,Na,Zn)3Sb2, (Mg,Li,Cd)3Sb2, (Mg,Ag)3Sb2, etc. Among these, MgAgSb is particularly preferred because it generates electromotive force even at relatively low temperatures.

[0021] The thickness of the thermoelectric material section 110 is not particularly limited and is selected as appropriate according to the desired thermoelectric conversion performance, but is usually around 2 to 5 mm.

[0022] (Conductive layer) In this embodiment, the conductive layer 120 is a layer that prevents the diffusion of components in the connecting layer 130 and components in the first electrode 140 and the second electrode 150. On the other hand, it is also a layer that transmits the current generated in the thermoelectric material section 110 to either the first electrode 140 side or the second electrode 150 side.

[0023] As described above, the conductive layer 120 may be a layer formed by spraying, that is, a layer having a thickness of 5 μm or more and 100 μm or less and containing at least one element selected from the group consisting of transition metals, zinc, aluminum, and silicon. In FIG. 1B, the conductive layer 120 is disposed on both sides of the thermoelectric material portion 110, but the conductive layer 120 may be disposed only on one side of the thermoelectric material portion 110. Further, in FIG. 1B, the conductive layers 120 are disposed on both sides of the N-type thermoelectric material portion 110N and the P-type thermoelectric material portion 110P, respectively. However, when the N-type thermoelectric material portion 110N is composed of a thermoelectric conversion material containing magnesium, antimony, etc., and the P-type thermoelectric material portion 110P is composed of a thermoelectric conversion material not containing magnesium, antimony, etc., the conductive layer 120 may be disposed only on the N-type thermoelectric material portion 110N side. Also, the reverse may be true.

[0024] The material constituting the conductive layer 120 only needs to contain at least one element selected from the group consisting of transition metals, zinc, aluminum, and silicon, and may contain two or more of these. Specific examples of the material constituting the conductive layer 120 include Ni, Fe, Al, Zn, Ag, and alloys thereof. Among these, Ni alone, Fe alone, and Al alone are more preferable from the viewpoints of availability, electrical conductivity, and ease of spraying.

[0025] Note that the electrical conductivity of the conductive layer 120 mainly depends on the electrical conductivity of the material constituting it. Therefore, the electrical conductivity of the material constituting the conductive layer 120 is preferably 1×10 6 S / m or more, and more preferably 10×10 6 S / m or more. Also, in order to allow electricity to flow between the conductive layer 120 and the thermoelectric material portion 110, it is necessary to lower the contact resistance between the two. Specifically, the contact resistance between the conductive layer 120 and the thermoelectric material portion 110 is preferably 5×10 -9 Ωm 2 or less, and more preferably 1×10 -9 Ωm 2 or less. When the electrical conductivity of the material constituting the conductive layer 120 is 10×10 6The contact resistance between the conductive layer 120 and the thermoelectric material part 110 is 1 × 10⁻¹⁰ or greater, and the contact resistance between the conductive layer 120 and the thermoelectric material part 110 is 1 × 10⁻¹⁰. -9 Ωm 2 The following conditions make it easier to efficiently transmit the current generated in the thermoelectric material section 110 to the first electrode 140 or the second electrode 150.

[0026] The thickness of the conductive layer 120 may be 5 μm or more and 100 μm or less, and preferably 50 μm or more and 100 μm or less.

[0027] (Connection layer) The connecting layer 130 is a layer for connecting the conductive layer 120 described above with the first electrode 140 or the second electrode 150 described later. However, if the conductive layer 120 and the first electrode 140 or the second electrode 150 can be directly connected, the connecting layer 130 may be omitted.

[0028] The type and thickness of the connecting layer 130 are not particularly limited as long as it is a layer with sufficient conductivity. For example, it may be a layer made of solder or brazing material, or a layer made by firing metal nanoparticles. For example, it may be a layer made by applying and firing silver paste.

[0029] The thickness of the connecting layer 130 is preferably 1 μm or more and 100 μm or less, and more preferably 1 μm or more and 50 μm or less.

[0030] (First electrode and second electrode) The first electrode 140 and the second electrode 150 are formed in a patterned shape, as shown in Figures 1A and 1B. The shape and thickness of the first electrode 140 and the second electrode 150 are not particularly limited, as long as it is possible to connect the N-type thermoelectric material section 110N and the P-type thermoelectric material section 110P in series and extract the current generated by the thermoelectric material section 110 to the outside.

[0031] The first electrode 140 and the second electrode 150 should be made of a material that has sufficient conductivity in the operating environment of the thermoelectric conversion element 100. It is also more preferable that their coefficient of thermal expansion is close to that of the thermoelectric material 110 (P-type thermoelectric material 110P or N-type thermoelectric material 110N). Specific examples of the first electrode 140 and the second electrode 150 include pure copper, pure aluminum, pure silver, etc.

[0032] (substrate) The substrate 160 is a component for supporting each of the above-mentioned components, and any substrate that is insulating and does not deform in the operating environment of the thermoelectric conversion element 100 is acceptable. Examples of substrate 160 include ceramic materials such as aluminum oxide, aluminum nitride, and silicon nitride. The shape and thickness of the substrate 160 are appropriately selected according to the application of the thermoelectric conversion element 100, and may be, for example, a flat plate or a three-dimensional component.

[0033] (others) In the above description, the substrate 160 was placed only on the side of the second electrode 150, but if necessary, the substrate may also be placed on the side of the first electrode 140. Furthermore, the substrate 160 does not have to be placed on either the first electrode 140 or the second electrode 150.

[0034] Furthermore, in the above description, a conductive layer 120, a connecting layer 130, and electrodes (first electrode 140, second electrode 150) were arranged on both sides of the thermoelectric material portion 110. However, the conductive layer 120 may also function as the electrodes (first electrode 140, second electrode 150). In this case, as shown in the plan view of Figure 2A and the cross-sectional view of Figure 2B (cross-sectional view along line AA in Figure 2A), the thermoelectric conversion element 200 can have a configuration comprising a thermoelectric material portion 110, two conductive layers 120 arranged on both sides of the thermoelectric material portion 110, and a substrate 160 arranged adjacent to one of the conductive layers 120. The thermoelectric material portion 110, conductive layer 120, and substrate 160 in the thermoelectric conversion element 200 of this embodiment are the same as the thermoelectric material portion 110, conductive layer 120, and substrate 160 described above.

[0035] 2. Method for manufacturing a thermoelectric element Next, the method for manufacturing the thermoelectric element described above will be explained. However, the method for manufacturing the thermoelectric element described above is not limited to this method.

[0036] The method for manufacturing the thermoelectric conversion element of the present invention may include a step of preparing a thermoelectric material portion containing magnesium and antimony and / or bismuth (thermoelectric material portion preparation step), and a step of forming a conductive layer by thermal spraying a material containing at least one element selected from the group consisting of transition metals, zinc, aluminum, and silicon onto the thermoelectric material portion (conductive layer formation step). If necessary, the method may further include a step of joining the conductive layer to an electrode, or a step of joining the electrode (or conductive layer) to a substrate.

[0037] (Thermoelectric materials department preparation process) In the thermoelectric material preparation step, the above-mentioned P-type thermoelectric material and N-type thermoelectric material are prepared. The P-type thermoelectric material and N-type thermoelectric material may be formed by, for example, firing. For example, the composition of the N-type thermoelectric material is Mg3Y 0.02 S 1.5 Bi 0.5 In this case, the following adjustments can be made. First, Mg, Y, Sb, and Bi are mixed in the above-mentioned ratios and fired in a heating furnace or the like. The resulting fired body is pulverized into a powder. Then, it is pressed at a predetermined temperature and pressure to obtain the desired shape. This results in Mg3Y 0.02 S 1.5 Bi 0.5 A sintered body is obtained, which can be used as the N-type thermoelectric material. The P-type thermoelectric material can be formed in the same manner.

[0038] (Conductivity formation process) The conductive formation process involves spraying a conductive layer material onto the surface of the thermoelectric material prepared in the thermoelectric material preparation process described above, thereby forming a conductive layer. The material used in this process is appropriately selected according to the desired material.

[0039] Furthermore, the thermal spraying method is not particularly limited and any method may be used, such as low-pressure plasma spraying, atmospheric pressure plasma spraying, or ultrafast thermal spraying. When performing thermal spraying, metal particles with an average particle size of about 50 μm (particles of a material containing at least one element selected from the group consisting of transition metals, zinc, aluminum, and silicon that form the conductive layer described above) are prepared as the material. Then, the metal particles are heated to a molten or softened state. Then, the conductive layer is formed by spraying the particles onto the surface of the thermoelectric material part from a known thermal spraying apparatus until the desired thickness is reached.

[0040] As mentioned above, the thickness of the conductive layer is preferably 5 μm to 100 μm, and more preferably 50 μm to 100 μm. [Examples]

[0041] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited in any way thereto.

[0042] [Method for measuring interfacial resistance] In the following examples and comparative examples, the interfacial resistance between the thermoelectric material and the conductive layer was measured using the four-terminal method. The four-terminal method allows for the measurement of the resistance distribution by moving the position of the measurement probe, thereby enabling evaluation of the resistance at the interface.

[0043] [Comparative Example 1] (Mg3Y 0.02 S 1.5 Bi 0.5 (composition of) As starting materials, 99.9% pure Mg, 99.9999% pure Sb, 99.9999% pure Bi, and 99.9% pure Y were used. These were combined to form Mg3Y 0.02 S 1.5 Bi 0.5The materials were weighed to achieve the specified values. These were placed in an alumina tin tube and sealed inside a SUS316L stainless steel pipe. The sealed raw materials were fired at 1180°C for 10 minutes, and then the temperature was lowered to room temperature. The resulting molten material was pulverized into a powder, and then a dense sintered body was obtained by holding it in a hot press at 70 MPa and 600°C for 1 hour.

[0044] (InGa coating) The above Mg3Y cut into a rectangular parallelepiped shape. 0.02 S 1.5 Bi 0.5 InGa was applied to the sintered body (thermoelectric material part) to form a 1 μm thick InGa layer (conductive layer). Then, it was sandwiched between Cu blocks, and the Cu blocks and Mg3Y 0.02 S 1.5 Bi 0.5 When the resistance between them was evaluated, it was 5.9 × 10 -3 Ωcm 2 This was an extremely high value.

[0045] [Comparative Example 2] (Ni plating) Mg3Y prepared in the same manner as in Comparative Example 1 0.02 S 1.5 Bi 0.5 A conductive layer (Ni layer) was formed by bonding a 1 μm thick layer of Ni to the sintered body (thermoelectric material part) by plating. Then, this Ni layer was solder-bonded to the Cu block. As a result, Mg3Y 0.02 S 1.5 Bi 0.5 The electrical resistance increased 30 times compared to before the Ni layer was formed, and the thermoelectric power decreased to one-third. In other words, the thermoelectric material itself deteriorated significantly, and the performance of the device decreased drastically.

[0046] [Comparative Example 3] (Ni deposition) Mg3Y prepared in the same manner as in Comparative Example 1 0.02 S 1.5 Bi 0.5 A conductive layer (Ni layer) with a thickness of 1 μm was formed by bonding Ni to the sintered body (thermoelectric material part) by vapor deposition. Then, the Ni layer was soldered to the Cu block.0.02 S 1.5 Bi 0.5 When the interfacial resistance between them was evaluated, it was found to be 1 × 10 -2 Ωcm 2 The value was extremely high.

[0047] [Comparative Example 4] (Joining by Cerasolza®) Mg3Y prepared in the same manner as in Comparative Example 1 0.02 S 1.5 Bi 0.5 A Cu block was bonded to the sintered body (thermoelectric material part) using Cerasolza (registered trademark, conductive layer). The thickness of the conductive layer was 1 μm. Cu block and Mg3Y 0.02 S 1.5 Bi 0.5 When the interfacial resistance between them was evaluated, it was found to be 1 × 10 -3 Ωcm 2 The value was extremely high.

[0048] [Comparative Example 5] (Al diffusion junction) Mg3Y 0.02 S 1.5 Bi 0.5 The powder is sintered together with Al foil and Cu foil by hot pressing, and Mg3Y 0.02 S 1.5 Bi 0.5 Al foil and Cu foil (conductive layer) were bonded to the sintered body (thermoelectric material part). Specifically, Mg3Y 0.02 S 1.5 Bi 0.5 A 50 μm thick aluminum foil was placed on top of the powder, and then a 300 μm thick copper foil was placed on top of that. These were hot-pressed under the conditions of 70 MPa, 800°C, and 1 hour. As a result, Mg3Y 0.02 S 1.5 Bi 0.5 We successfully bonded the sintered body (thermoelectric material part) to a conductive layer containing Al and Cu with a thickness of 300 μm. However, the bond between the Cu foil and Mg3Y 0.02 S 1.5 Bi 0.5 The interfacial resistance between the sintered body and the surface is 2 × 10⁻⁶ -4 Ωcm 2 The value was extremely high.

[0049] [Example 1] (Thermal spraying) Mg3Y prepared in the same manner as in Comparative Example 1 0.02 S 1.5 Bi 0.5 A 70 μm thick Ni layer (conductive layer) was bonded to the sintered body (thermoelectric material part) by thermal spraying. Then, the Ni layer and the Cu block were bonded together with Ag paste. When the interfacial resistance between the Cu block and the thermoelectric material part was measured, it was found to be 1 × 10⁻⁶. -5 Ωcm 2 The value was low. This is a practical value for a thermoelectric element used in a thermoelectric module, and such a thermoelectric element can be incorporated into a thermoelectric module. Figure 3 shows an SEM image of the thermoelectric element. Figure 4 shows the EDS mapping of the thermoelectric element. In Figure 4, the bright areas indicate the presence of Ni. Furthermore, Figure 5 shows the electrical resistance distribution of the thermoelectric element. From these results, it is clear that the interfacial resistance between the thermoelectric material and the conductive layer is extremely low. Figure 6 shows a photograph of the surface of the Ni layer (conductive layer) of the thermoelectric element as observed with a scanning electron microscope (SEM).

[0050] [Example 2] (Thermal spraying) A conductive layer with a thickness of 70 μm was formed in the same manner as in Example 1, except that Al was sprayed. Then, the Al layer and the Cu block were bonded with Ag paste. When the interfacial resistance between the Cu block and the thermoelectric material of the thermoelectric conversion element was measured, it was found to be 1 × 10⁻⁶. -5 Ωcm 2 The value was low. This is a practical value for a thermoelectric conversion element used in a thermoelectric module, and such a thermoelectric conversion element can be incorporated into a thermoelectric module.

[0051] [Example 3] (Thermal spraying) A conductive layer with a thickness of 70 μm was formed in the same manner as in Example 1, except that Fe was sprayed. Then, the Fe layer and the Cu block were bonded together with Ag paste. When the interfacial resistance between the Cu block and the thermoelectric material of the thermoelectric conversion element was measured, it was found to be 1 × 10⁻⁶.-5 Ωcm 2 The value was low. This is a practical value for a thermoelectric conversion element used in a thermoelectric module, and such a thermoelectric conversion element can be incorporated into a thermoelectric module. [Industrial applicability]

[0052] According to the present invention, a thermoelectric conversion element is obtained having a thermoelectric material portion containing magnesium and antimony and / or bismuth, and a conductive layer adjacent to the thermoelectric material portion, with low interfacial resistance. Furthermore, the manufacturing method of the thermoelectric conversion element of the present invention is suitable for mass production. [Explanation of Symbols]

[0053] 100, 200 thermoelectric conversion elements 110 Thermoelectric Materials Department 110N N type thermoelectric material section 110P P type thermoelectric material section 120 conductive layer 130 Connecting Layers 140 1st electrode 150 2nd electrode 160 circuit boards

Claims

1. A thermoelectric material part comprising magnesium, and antimony and / or bismuth, A conductive layer is disposed adjacent to the thermoelectric material portion, composed of one or more elements selected from the group consisting of transition metals and aluminum, and having a thickness of 5 μm to 100 μm. It has, The contact resistance between the thermoelectric material and the conductive layer is 5 × 10 －９ Ωm ２ The following: The thermoelectric material portion includes at least one material selected from the group consisting of (Mg, Y) 3 (Sb, Bi) 2, Mg 3 (Sb, Bi, Te) 2, Mg 3 (Sb, Bi, Se) 2, Mg 3 (Sb, Bi, S) 2, (Mg, La) 3 (Sb, Bi) 2, (Mg, Sc) 3 (Sb, Bi) 2, and MgAgSb. Thermoelectric conversion element.

2. The conductive layer comprises at least one element selected from the group consisting of iron, nickel, and aluminum. The thermoelectric conversion element according to claim 1.

3. A step of preparing a thermoelectric material part containing magnesium, as well as antimony and / or bismuth, The process involves thermal spraying a material composed of one or more elements selected from the group consisting of transition metals and aluminum onto the thermoelectric material portion to form a conductive layer with a thickness of 5 μm to 100 μm. Includes, The contact resistance between the thermoelectric material and the conductive layer is 5 × 10 －９ Ωm ２ The following is: A method for manufacturing a thermoelectric conversion element.

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