Thermoelectric elements and thermoelectric devices

Abstract

This thermoelectric conversion element (1) is made of a material that can be magnetized in any direction in a zero magnetic field, has a rectangular shape extending in one direction (y direction), and is magnetized in the +z direction. When heat flow Q (∝−∇T) flows in the +x direction through the thermoelectric conversion element (1), a temperature difference occurs in the +x direction. As a result, due to the abnormal Nernst effect, the thermoelectric conversion element (1) generates an electromotive force V(∝M×(−∇T)) in the direction of the cross product (y direction) orthogonal to both the direction of heat flow Q (+x direction) and the direction of magnetization M (+z direction). Examples of materials for the thermoelectric conversion element (1) include a ferrimagnetic material of which the compositional formula is R2Co7 (R is a rare earth element).

Description

[Technical Field]

[0001] The present invention relates to thermoelectric elements and thermoelectric devices. [Background technology]

[0002] Thermoelectric modules, which convert the temperature difference of an object into voltage, have so far mainly utilized the Seebeck effect. However, due to the complexity of their structure and problems with the materials used, they have not become widespread. On the other hand, although their figure of merit is inferior to that of the Seebeck effect, thermoelectric modules using the anomalous Nernst effect are attracting considerable attention due to their simple structure and the versatility of the materials used (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-128998 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the anomalous Nernst effect generally occurs in ferromagnetic materials, and therefore reacts strongly to external magnetic fields. Furthermore, it is difficult to induce the anomalous Nernst effect in ferromagnetic materials at zero magnetic field, regardless of their shape. For this reason, using materials that are less sensitive to external magnetic fields is extremely important for the stable use of thermoelectric modules utilizing the anomalous Nernst effect.

[0005] This invention has been made in view of the above problems, and aims to provide a thermoelectric conversion element and a thermoelectric conversion device that are stable against external magnetic fields. [Means for solving the problem]

[0006] A thermoelectric conversion element according to the first aspect of the present invention is made of a material that can be magnetized in any direction in a zero magnetic field and exhibits an anomalous Nernst effect.

[0007] A thermoelectric conversion device according to a second aspect of the present invention includes a substrate, and a plurality of thermoelectric conversion elements provided on the substrate, each of which has a shape extending in one direction. The plurality of thermoelectric conversion elements are arranged in parallel in a direction orthogonal to the one direction, are electrically connected in series, are made of a material that can be magnetized in any direction in a zero magnetic field, and exhibit an anomalous Nernst effect.

[0008] A thermoelectric conversion device according to a third aspect of the present invention includes a first substrate, a plurality of first thermoelectric conversion elements provided on the first substrate, each of which has a shape extending in one direction, the plurality of first thermoelectric conversion elements being arranged in parallel in a direction orthogonal to the one direction, made of a first material that can be magnetized in any direction in a zero magnetic field, and exhibiting an anomalous Nernst effect; a second substrate; and a plurality of second thermoelectric conversion elements provided on the second substrate, each of which has a shape extending in one direction, the plurality of second thermoelectric conversion elements being arranged in parallel in a direction orthogonal to the one direction, made of a second material that can be magnetized in any direction in a zero magnetic field, and exhibiting an anomalous Nernst effect. The first material and the second material have Nernst coefficients of opposite signs to each other, and the plurality of first thermoelectric conversion elements and the plurality of second thermoelectric conversion elements are alternately and electrically connected in series such that their magnetization directions are the same. Effects of the Invention

[0009] According to the present invention, by using a material that exhibits the anomalous Nernst effect and can be magnetized in any direction in a zero magnetic field, it is possible to achieve thermoelectric conversion that is stable with respect to an external magnetic field. Brief Description of the Drawings

[0010] [Figure 1] It is a schematic diagram for explaining the thermoelectric mechanism by the thermoelectric conversion element according to the present embodiment. [Figure 2] It is a graph showing the temperature dependence of the Hall resistivity of GdCo₃, Gd₂Co₇ and GdCo₅, and the temperature dependence of the magnetization of Gd₂Co₇. [Figure 3A] It is a schematic diagram showing the crystal structure of Gd₂Co₇ type. [Figure 3B]It is a schematic diagram showing the crystal structure of Ce₂Ni₇ type. [Figure 4A] It is a graph showing the magnetic field dependence of the Nernst coefficient of Gd₂Co₇ single crystal. [Figure 4B] It is a graph showing the magnetic field dependence of the Nernst coefficient of Ho₁.₂Gd₀.₈Co₇ single crystal. [Figure 4C] It is a graph showing the temperature dependence of magnetization of Ho₁.₂Gd₀.₈Co₇. [Figure 4D] It is a graph showing the temperature dependence of magnetization of various Gd-Co alloys. [Figure 4E] It is a graph showing the Nernst coefficient of R₂Co₇ polycrystals for various rare earth elements R. [Figure 5] It is a perspective view showing the configuration of the thermoelectric conversion device according to Example 1 of the present embodiment. [Figure 6A] It is a schematic diagram showing the configuration of the first structure of the thermoelectric conversion device according to Example 2 of the present embodiment. [Figure 6B] It is a schematic diagram showing the configuration of the second structure of the thermoelectric conversion device according to Example 2 of the present embodiment. [Figure 7] It is a schematic diagram showing the configuration of the thermoelectric conversion device according to Example 2. [Figure 8] It is a schematic external view of the thermoelectric conversion device according to Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. Throughout the drawings, identical or similar components are denoted by the same reference numerals. In addition, the drawings are schematic, and the relationship between planar dimensions and thickness, and the ratio of thicknesses of each member differ from actual values. Needless to say, the drawings also include portions where the relationships and ratios of dimensions differ from each other.

[0012] First, with reference to FIG. 1, a thermoelectric conversion element and its thermoelectric mechanism according to an embodiment of the present invention will be described.

[0013] As shown in FIG. 1, the thermoelectric conversion element 1 according to the present embodiment has a rectangular parallelepiped shape extending in one direction (y-direction), has a predetermined thickness (length in the z-direction), and is magnetized in the +z direction. When a heat flow Q (∝-∇T) in the +x direction flows through the thermoelectric conversion element 1, a temperature difference is generated in the +x direction. As a result, an electromotive force V (∝M×(-∇T)) is generated in the thermoelectric conversion element 1 in the direction of the outer product (y-direction) orthogonal to both the direction of the heat flow Q (+x direction) and the direction of the magnetization M (+z direction) due to the anomalous Nernst effect.

[0014] The present embodiment targets thermoelectric conversion elements that are made of a material capable of being magnetized in any direction in zero magnetic field and exhibit the anomalous Nernst effect. To be capable of being magnetized in any direction in zero magnetic field, the shape magnetic anisotropy needs to be small. For this purpose, the magnetization needs to be low, and it is preferable that the magnetization is 2 kG (kilogauss) or less at the temperature of an actual usage environment, and 1 kG or less is more preferable.

[0015] Materials that can be magnetized in any direction in zero magnetic field include ferromagnets, antiferromagnets, and ferrimagnets, and examples thereof include alloys composed of a rare earth element (R) and cobalt (Co). Examples of such R-Co alloys include RCo₂ (R=Gd), RCo₃ (R=Gd, Tb, Dy, Er, Tm, Lu), R₂Co₇ (R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu), R₅Co 19 (R=La, Pr, Nd, Sm), RCo₅ (R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er), R₂Co 17 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), RCo 13 (R=La), R₁ 2-x R₂ x Co₇ (0<x<2, R₁ and R₂ are different rare earth elements). Hereinafter, ferrimagnets, which have lower magnetization than ferromagnets and can exhibit the anomalous Nernst effect in zero magnetic field regardless of shape, will be mainly discussed.

[0016] A ferrimagnetic material has a magnetization compensation temperature T k , and before and after T k , the relative magnitudes of the magnetizations of the two sublattices are interchanged. Therefore, the magnetization of the ferrimagnetic material is relatively small in the vicinity of T k , resulting in weakened shape magnetic anisotropy. Accordingly, unlike ferromagnetic materials, ferrimagnetic materials can have their magnetization stably oriented in any direction. As described above, when the magnetization is small, the magnetization can be stably oriented in any direction such as a direction perpendicular or oblique to the longitudinal direction of a fine wire.

[0017] Among ferrimagnetic materials, it is known that for alloys of rare earth elements and Co, T k is near room temperature. As shown in Table 1, for a ferrimagnetic material represented by the composition formula R2Co7 (where R is a rare earth element), when R is Gd, T k is 428K, and as the atomic number of R increases (Tb, Dy, Ho, Er), T k decreases monotonically. These compounds have a Curie temperature T c that is sufficiently higher than room temperature (300K) and remains stably up to approximately 600K to 700K.

[0018] [Table 1] Here, Table 1 and Table 2 described later are based on the following document. “Duc N H. Intersublattice Exchange Coupling in The Rare Earth-Transition Metal Intermetallics[J]. Handbook on the Physics and Chemistry of Rare Earths; Gschneidner, KA, Jr., Eyring, L., Eds, 2014: 339-398.”

[0019] FIG. 2 shows the temperature dependence of the Hall resistivity of GdCo3 single crystals, Gd2Co7 single crystals and GdCo5 single crystals, and the temperature dependence of the magnetization of Gd2Co7 single crystals. FIG. 2 is based on the following document. Ogawa A, Katayama T, Hirano M, et al. General Treatment of Anomalous Hall Effect and Kerr Rotation in Rare Earth Cobalt Systems[J]. Japanese Journal of Applied Physics, 1976, 15(S1): 87.

[0020] As shown in Figure 2, in the ferrimagnetic material Gd2Co7, the magnetization of Gd (upward arrow) and Co (downward arrow) are directed in opposite directions, T k At lower temperatures, Gd has greater magnetization than Co, T k At higher temperatures, Gd has less magnetization than Co. k The magnetizations of Gd and Co balance out, and the magnetization of Gd2Co7 (black circle) becomes zero. Also, the Hall resistivity of Gd2Co7 (white circle) is T k The sign reverses at this point. k When the sign of the anomalous Hall effect (Hall resistivity) is reversed, the sign of the anomalous Nernst effect (Nernst coefficient) is also reversed.

[0021] As shown in Figures 3A and 3B, the crystal structure of R2Co7 has two forms: a rhombohedral Gd2Co7 type structure and a hexagonal Ce2Ni7 type structure. The rhombohedral structure shown in Figure 3A has a space group of R-3m, and lattice constants of a=5.023Å, b=5.023Å, c=36.315Å, α=90.000°, β=90.000°, and γ=120.000°. The hexagonal structure shown in Figure 3B has a space group of P63 / mmc, and lattice constants of a=5.022Å, b=5.022Å, c=24.190Å, α=90.000°, β=90.000°, and γ=120.000°. Thus, in the rhombohedral crystal system, the length of the c-axis is approximately 1.5 times that of the hexagonal crystal system.

[0022] Table 2 shows the crystal structures of R2Co7 when R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Lu. Ce2Co7, Pr2Co7, Sm2Co7, and Gd2Co7 can take on both rhombohedral and hexagonal crystal structures. [Table 2]

[0023] Figure 4A shows the magnetic field dependence of the Nernst coefficient of a Gd2Co7 single crystal at 300K when a magnetic field parallel to the c-axis is applied. Figure 4B shows the magnetic field dependence of the Nernst coefficient at 300K when a magnetic field parallel to the c-axis is applied. 1.2 Gd 0.8 Figure 4C shows the magnetic field dependence of the Nernst coefficient of a Co7 single crystal. 1.2 Gd 0.8 This shows the temperature dependence of the magnetization of Co7. As mentioned above, the T k Ho is sufficiently higher than room temperature (see Table 1). On the other hand, as shown in Figure 4C, 1.2 Gd 0.8 Co7 T k The temperature is 278K, which is lower than room temperature.

[0024] From Figures 4A and 4B, at room temperature (300K), Gd2Co7 and Ho 1.2 Gd 0.8 It can be seen that the Nernst coefficient for Co7 has the opposite sign, but its absolute value is almost the same. Furthermore, the absolute value of the Nernst coefficient for both samples approaches the world record high value at room temperature (~6 μV / K).

[0025] Figures 4A and 4B show Gd2Co7 and Ho at room temperature. 1.2 Gd 0.8 This reflects the fact that Co7 has very low magnetization and high coercivity. This means that once the magnetization is directed in a specific direction by a magnetic field, it is not easy to maintain that direction and reverse it. Furthermore, because these materials have low magnetization, they have weak shape magnetic anisotropy, and the magnetization can be manipulated in any direction, not just the longitudinal direction of a thin wire, for example.

[0026] Fig. 4D shows the temperature dependence of magnetization of Gd2Co7, GdCo2, GdCo3, GdCo5, Gd 2.2 Co 16.6 and Gd2Co 17 . Fig. 4D is based on the following document. Katayama T, Shibata T, Magnetic properties of some gadolinium-Cobalt intermetallic compounds[J]. Journal of Magnetism and Magnetic Materials, 1981, 23(2): 173-182.

[0027] As is clear from Fig. 4D, the ferrimagnetic Gd2Co7 has a magnetization value that is 1 / 5 to 1 / 10 of that of ferromagnetic materials such as GdCo5. The magnetization value can be further reduced by finely adjusting the composition of the rare earth element. Specifically, as shown in Ho 1.2 Gd 0.8 Co7 shown in Figs. 4B and 4C, adding another rare earth element to R2Co7 can obtain a ternary compound with even lower magnetization. That is, a low-magnetization ternary compound represented by the composition formula R1 2-x R2 x Co7 (0<x<2, R1 and R2 are different rare earth elements from each other) can be obtained.

[0028] Fig. 4E shows the Nernst coefficients of R2Co7 polycrystals when a magnetic field B of 1 T is applied at 300 K for R = Gd, Tb, Dy, Y, Ho, Er. It can be seen from Fig. 4E that even in R2Co7 polycrystals (particularly, when R = Gd, Tb, Y, Ho, Er), the absolute value of the Nernst coefficient exhibits a relatively large value (about 2 to 4 µV / K).

[0029] As described above, by using the thermoelectric conversion element 1 which is made of a material that can be magnetized in any direction in zero magnetic field like a ferrimagnetic material and exhibits the anomalous Nernst effect, it is possible to realize a thermoelectric mechanism that is stable against external magnetic fields such as the leakage magnetic field of a motor.

[0030] Next, we will describe thermoelectric conversion devices according to Examples 1 and 2, which modularize the thermoelectric conversion element 1 of this embodiment. [Examples]

[0031] Figure 5 shows the external configuration of the thermoelectric conversion device 100 according to Embodiment 1 of this embodiment. The thermoelectric conversion device 100 comprises a substrate 22 and a power generation body 23 mounted on the substrate 22. In the thermoelectric conversion device 100, when a heat flow Q flows from the substrate 22 towards the power generation body 23, a temperature difference in the direction of heat flow occurs in the power generation body 23, and a voltage V is generated in the power generation body 23 due to the abnormal Nernst effect.

[0032] The substrate 22 has a first surface 22a on which the power generation element 23 is placed, and a second surface 22b opposite to the first surface 22a. Heat from a heat source (not shown) is applied to the second surface 22b. Examples of materials for the substrate 22 include MgO, Si, SiO2, Al2O3, etc., but are not particularly limited.

[0033] The power generator 23 has a plurality of first thermoelectric conversion elements 24 and a plurality of second thermoelectric conversion elements 25, each having an L-shaped three-dimensional form of the same size. The first thermoelectric conversion elements 24 and the second thermoelectric conversion elements 25 have Nernst coefficients with opposite signs to each other and are made of a first material and a second material, respectively, that can be magnetized in any direction in a zero magnetic field. For example, the first material and the second material are different ferrimagnetic materials. For example, Gd2Co7 as the first material (Figure 4A) and Ho as the second material. 1.2 Gd 0.8 Co7 (Figure 4B) can be used.

[0034] As shown in Figure 5, the multiple first thermoelectric elements 24 and the multiple second thermoelectric elements 25 are arranged alternately in parallel on the substrate 22, in the direction perpendicular to their respective longitudinal direction (x direction) and direction (y direction). Furthermore, the first thermoelectric elements 24 and the second thermoelectric elements 25 are arranged so that their respective magnetization directions M1 and M2 are the same. Note that the number of first thermoelectric elements 24 and second thermoelectric elements 25 constituting the power generation unit 23 is not limited.

[0035] The first thermoelectric conversion element 24 is defined as having a first end face 24a at the +x end of one side (+y side) in the longitudinal direction (x direction), and a second end face 24b at the -x end of the other side (-y side). The second thermoelectric conversion element 25 is defined as having a first end face 25a at the -x end of one side (+y side) in the longitudinal direction (x direction), and a second end face 25b at the +x end of the other side (-y side).

[0036] The first end face 25a of the second thermoelectric element 25 is connected to the second end face 24b of the first thermoelectric element 24 adjacent to it on the +y side, and the second end face 25b of the second thermoelectric element 25 is connected to the first end face 24a of the first thermoelectric element 24 adjacent to it on the opposite side (-y side). As a result, multiple first thermoelectric elements 24 and multiple second thermoelectric elements 25 are electrically connected in series. That is, the power generation unit 23 is arranged in a meandering manner on the first surface 22a of the substrate 22. The first thermoelectric elements 24 and the second thermoelectric elements 25 are insulated from each other except at the connection points.

[0037] When heat is applied from the heat source to the second surface 22b of the substrate 22, a heat flow Q in the +z direction flows toward the power generator 23. When a temperature difference is created by the heat flow Q, due to the anomalous Nernst effect, an electromotive force E1 is generated in the first thermoelectric conversion element 24 in a direction (-x direction) perpendicular to both the direction of magnetization M1 (-y direction) and the direction of heat flow Q (+z direction). In the second thermoelectric conversion element 25, due to the anomalous Nernst effect, an electromotive force E2 is generated in a direction (+x direction) perpendicular to both the direction of magnetization M2 (-y direction) and the direction of heat flow Q (+z direction).

[0038] As described above, the first thermoelectric element 24 and the second thermoelectric element 25, which are arranged in parallel, are electrically connected in series. Therefore, the electromotive force E1 generated in the first thermoelectric element 24 can be applied to the adjacent second thermoelectric element 25. Furthermore, since the electromotive force E1 generated in the first thermoelectric element 24 and the electromotive force E2 generated in the adjacent second thermoelectric element 25 are in opposite directions, the electromotive forces in the adjacent first thermoelectric element 24 and second thermoelectric element 25 are added together, increasing the output voltage V. [Examples]

[0039] Next, with reference to Figures 6A to 8, Example 2 of this embodiment will be described.

[0040] Example 1 describes a thermoelectric conversion device 100 in which a first thermoelectric conversion element 24 and a second thermoelectric conversion element 25 having opposite Nernst coefficients are provided on the same surface of a substrate 22. Example 2 describes a thermoelectric conversion device in which such two types of thermoelectric conversion elements are provided on separate substrates.

[0041] The thermoelectric conversion device according to Embodiment 2 consists of a first structure 201 shown in Figure 6A and a second structure 202 shown in Figure 6B. As shown in Figure 6A, the first structure 201 comprises a first substrate 210 and a plurality of rectangular parallelepiped-shaped first thermoelectric conversion elements 231 to 234 of the same size provided on the first surface 211 of the first substrate 210. The first thermoelectric conversion elements 231 to 234 are arranged in parallel at equal intervals in a direction perpendicular to the longitudinal direction. Similarly, as shown in Figure 6B, the second structure 202 comprises a second substrate 220 and a plurality of second thermoelectric conversion elements 241 to 244 provided on the first surface 221 of the second substrate 220. The second thermoelectric conversion elements 241 to 244 have the same shape and size as the first thermoelectric conversion elements 231 to 234 and are arranged in parallel at equal intervals in a direction perpendicular to the longitudinal direction. These thermoelectric elements are formed on a substrate, for example, by sputtering. Examples of materials for the first substrate 210 and the second substrate 220 include MgO, Si, SiO2, Al2O3, etc., but are not particularly limited.

[0042] The first thermoelectric elements 231-234 are made of a first material, and the second thermoelectric elements 241-244 are made of a second material. The first and second materials have Nernst coefficients with opposite signs and can be magnetized in any direction in a zero magnetic field; for example, they are different ferrimagnetic materials. For example, Gd2Co7 as the first material (Figure 4A) and Ho as the second material. 1.2 Gd 0.8 Co7 (Figure 4B) can be used.

[0043] Figures 6A to 8 show an example in which four first thermoelectric elements 231 to 234 are arranged on the first substrate 210 and four second thermoelectric elements 241 to 244 are arranged on the second substrate 220, but the number of thermoelectric elements on each substrate is not limited.

[0044] The first substrate 210 is provided with through-holes that penetrate the substrate 210 in the vicinity of one or both ends in the longitudinal direction of each first thermoelectric conversion element. Specifically, as shown in Figure 7, a through-hole 272 is provided near one end of the first thermoelectric conversion element 231, through-holes 273 and 274 are provided near both ends of the first thermoelectric conversion element 232, through-holes 275 and 276 are provided near both ends of the first thermoelectric conversion element 233, and through-holes 277 and 278 are provided near both ends of the first thermoelectric conversion element 234.

[0045] Similarly, the second substrate 220 is provided with through-holes that penetrate the substrate 220 in the vicinity of one or both ends in the longitudinal direction of each second thermoelectric conversion element. Specifically, as shown in Figure 7, through-holes 281 and 282 are provided near both ends of the second thermoelectric conversion element 241, through-holes 283 and 284 are provided near both ends of the second thermoelectric conversion element 242, through-holes 285 and 286 are provided near both ends of the second thermoelectric conversion element 243, and through-hole 287 is provided near one end of the second thermoelectric conversion element 244.

[0046] Conductors 204 pass through the through-holes of the first substrate 210 and the second substrate 220. First and second terminals are provided at both ends of each first thermoelectric conversion element, and first and second terminals are provided at both ends of each second thermoelectric conversion element. Conductors 204 are connected to these first and second terminals. The second surface 212 of the first substrate 210 and the second surface 222 of the second substrate 220 are bonded together with adhesive to form a thermoelectric conversion device 200 as shown in Figure 8.

[0047] As shown in Figure 7, the second terminal 252 of the first thermoelectric element 231 is connected to the first terminal 261 of the second thermoelectric element 241 via through-holes 272 and 281, the second terminal 262 of the second thermoelectric element 241 is connected to the first terminal 253 of the first thermoelectric element 232 via through-holes 282 and 273, the second terminal 254 of the first thermoelectric element 232 is connected to the first terminal 263 of the second thermoelectric element 242 via through-holes 274 and 283, and the second terminal 264 of the second thermoelectric element 242 is connected to through-holes 284 and The first thermoelectric element 233's first terminal 255 is connected via through-holes 275, the second terminal 256 of the first thermoelectric element 233 is connected via through-holes 276 and 285 to the first terminal 265 of the second thermoelectric element 243, the second terminal 266 of the second thermoelectric element 243 is connected via through-holes 286 and 277 to the first terminal 257 of the first thermoelectric element 234, and the second terminal 258 of the first thermoelectric element 234 is connected via through-holes 278 and 287 to the first terminal 267 of the second thermoelectric element 244.

[0048] Thus, the first thermoelectric elements 231-234 and the second thermoelectric elements 241-244 are electrically connected in series alternately. Also, in Figures 7 and 8, the magnetization of the first thermoelectric elements 231-234 and the magnetization of the second thermoelectric elements 241-244 are oriented in the same direction (+y direction).

[0049] For example, when a heat flow Q in the +z direction is passed through the thermoelectric conversion device 200, and a temperature difference is created by the heat flow Q, an abnormal Nernst effect causes an electromotive force to be generated in the +x direction in the first thermoelectric conversion elements 231 to 234 and an electromotive force to be generated in the -x direction in the second thermoelectric conversion elements 241 to 244. As a result, the electromotive forces generated in each thermoelectric conversion element are added together, and a voltage V generated between the first terminal 251 of the first thermoelectric conversion element 231 and the second terminal 268 of the second thermoelectric conversion element 244 can be output.

[0050] In Example 2, by forming a first thermoelectric conversion element and a second thermoelectric conversion element having Nernst coefficients with opposite signs on separate substrates, and fabricating the first structure 201 and the second structure 202, it becomes possible to fabricate the thermoelectric conversion device 200 using a simple process. Furthermore, since the density of thermoelectric conversion elements is approximately twice that of the thermoelectric conversion device 100 in Example 1 (Figure 5), in which the first thermoelectric conversion element 24 and the second thermoelectric conversion element 25 are provided on the same surface of the substrate 22, it becomes possible to increase the output voltage.

[0051] In Figures 7 and 8, an example is shown in which the second surface 212 of the first substrate 210 and the second surface 222 of the second substrate 220 are bonded together, and the first surface 211 of the first substrate 210 and the first surface 221 of the second substrate 220 face in opposite directions. However, a configuration in which these first surfaces 211 and 221 face in the same direction is also possible.

[0052] Furthermore, through-holes are not necessarily required in the first substrate 210 and the second substrate 220. As long as the first thermoelectric elements 231-234 on the first substrate 210 and the second thermoelectric elements 241-244 on the second substrate 220 are connected in series by the conductor 204, the conductor 204 may pass outside the first substrate 210 and the second substrate 220. [Explanation of Symbols]

[0053] 1 Thermoelectric element 22 circuit boards 23 Power generators 24, 231, 232, 233, 234 First thermoelectric conversion element 25, 241, 242, 243, 244 Second thermoelectric conversion element 100, 200 Thermoelectric Conversion Devices 201 First structure 202 Second structure 204 Conductor 210 First substrate 211 Page 1 212 2nd page 220 Second board 221 Page 1 222 2nd page 251, 253, 255, 257, 261, 263, 265, 267 1st terminal 252, 254, 256, 258, 262, 264, 266, 268 2nd terminal 272-278, 281-287 Through-hole

Claims

1. A thermoelectric conversion element made of a ferrimagnetic material that generates electromotive force through the anomalous Nernst effect, The ferrimagnetic material has a composition formula R1 ２－ｘ R2 ｘ Co ７ It is represented as such that R1 and R2 are different rare earth elements, 0 < x < 2, and R1 ２ Co ７ A thermoelectric conversion element that is a ternary compound in which part of the R1 site is occupied by R2.

2. circuit board and A plurality of thermoelectric conversion elements, each made of a ferrimagnetic material, provided on the substrate and having a shape that extends in one direction, generate electromotive force due to an abnormal Nernst effect, A thermoelectric conversion device, The plurality of thermoelectric conversion elements are arranged in parallel in a direction perpendicular to the aforementioned one direction and are electrically connected in series. A thermoelectric device wherein at least one of the plurality of thermoelectric elements is defined as the thermoelectric element described in claim 1.

3. Of the plurality of thermoelectric conversion elements, two adjacent thermoelectric conversion elements consist of a first ferrimagnetic material and a second ferrimagnetic material having Nernst coefficients with opposite signs to each other. The thermoelectric conversion device according to claim 2, wherein the plurality of thermoelectric conversion elements are arranged so that their magnetization directions are the same.

4. The first ferrimagnetic material has a composition formula R ２ Co ７ The thermoelectric conversion device according to claim 3, wherein R is a rare earth element and the second ferrimagnetic material is the ternary compound.

5. First substrate and A plurality of first thermoelectric conversion elements are provided on the first surface of the first substrate, each having a shape that extends in one direction, arranged in parallel in a direction perpendicular to the aforementioned one direction, made of a first material that can be magnetized in any direction in a zero magnetic field, and generating an electromotive force by an abnormal Nernst effect, The second circuit board and A plurality of second thermoelectric conversion elements are provided on the first surface of the second substrate, each having a shape that extends in the one direction, and are arranged in parallel in a direction perpendicular to the one direction, and are made of a second material that can be magnetized in any direction in a zero magnetic field, and generate an electromotive force by an abnormal Nernst effect, Equipped with, The first material and the second material have Nernst coefficients with opposite signs to each other. One of the first and second materials is a ternary compound whose compositional formula is R1 2-x R2 x Co 7, where R1 and R2 are different rare earth elements, 0 < x < 2, and a portion of the R1 site in R1 2 Co 7 is occupied by R2. The plurality of first thermoelectric conversion elements and the plurality of second thermoelectric conversion elements are electrically connected in series alternately so that their magnetization directions are the same. A thermoelectric conversion device in which, when a heat flow is applied in a direction perpendicular to the first surface of the first substrate and the first surface of the second substrate, an electromotive force is generated in the plurality of first thermoelectric conversion elements and the plurality of second thermoelectric conversion elements in a direction perpendicular to both the direction of the temperature gradient and the magnetization direction.

6. The thermoelectric conversion device according to claim 5, wherein the first material and the second material are different ferrimagnetic materials.

7. The other of the first material and the second material has a composition formula R ２ Co ７ represented by, wherein R is a rare earth element. The thermoelectric conversion device according to claim 6.

8. The thermoelectric conversion device according to claim 5, wherein the second surface of the first substrate opposite to the first surface and the second surface of the second substrate opposite to the first surface are bonded together so that the first surface of the first substrate and the first surface of the second substrate face in opposite directions.

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