Thermoelectric conversion element and thermoelectric conversion device

Abstract

A thermoelectric conversion element 1a is provided with a first sheet 10, a thermoelectric conversion part 30, and a second sheet 20. The first sheet (10), the thermoelectric conversion unit (30), and the second sheet (20) are arranged in the order of the first sheet (10), the thermoelectric conversion unit (30), and the second sheet (20) in the thickness direction of the first sheet (10). The thermoelectric conversion unit 30 includes a magnetic body.

Description

Technical Field

[0001] This invention relates to thermoelectric conversion elements and thermoelectric conversion devices. Background Technology

[0002] Thermoelectric conversion elements that use magnetic materials have long been known.

[0003] For example, Patent Document 1 describes a thermoelectric conversion element formed from a substance represented by the composition formula of Fe3X and exhibiting an anomalous Nernst effect. As an example of this thermoelectric conversion element, a long, sheet-like (strip-like) thermoelectric conversion element is described, and a thermoelectric conversion device incorporating this sheet-like thermoelectric conversion element is also described (see Figure 9 of that document). In this thermoelectric conversion device, the sheet-like thermoelectric conversion element is wound to cover the outer surface of a hollow component.

[0004] Existing technical documents Patent documents Patent Document 1: International Publication No. 2020 / 218613 Summary of the Invention

[0005] The problem that the invention aims to solve With the advancement of the Internet of Things (IoT) society and digital transformation (DX), the demand for heat-related monitoring is constantly increasing in technological fields such as mechanical heat generation and physical condition monitoring. Furthermore, from the perspective of protecting the Earth's environment, it is important to suppress unwanted heat generation and improve energy efficiency. In various technological fields such as batteries, heat exchangers, and motors for electric vehicles (EVs), there is a growing expectation for improvements in systems responsible for thermal measurement to optimize operation.

[0006] Thermoelectric conversion elements using magnetic materials are promising technologies in response to such expectations. The thermoelectric conversion element described in Patent Document 1 is envisioned for use in a state of being wound around a hollow member. On the other hand, Patent Document 1 specifically studies the problems that may arise when the thermoelectric conversion element is used in a bent manner.

[0007] According to the inventors' research, it has been discovered for the first time that bending a thermoelectric conversion element using a magnetic material can reduce its thermoelectric conversion performance. This reduction in thermoelectric conversion performance may lead to a decrease in the accuracy of detecting physical quantities such as power generation and heat generation.

[0008] In view of this situation, the present invention provides a thermoelectric conversion element that uses a magnetic material and whose thermoelectric conversion performance is not easily changed when it is bent and used.

[0009] Methods for solving problems This invention provides a thermoelectric conversion element comprising: First sheet material Thermoelectric conversion unit, and Second sheet, The aforementioned first sheet, the aforementioned thermoelectric conversion unit, and the aforementioned second sheet are arranged in the thickness direction of the aforementioned first sheet in the following order: the aforementioned first sheet, the aforementioned thermoelectric conversion unit, and the aforementioned second sheet. The aforementioned thermoelectric conversion section includes a magnetic material.

[0010] In addition, the present invention provides a thermoelectric conversion device having the above-described thermoelectric conversion element.

[0011] Invention Effects The thermoelectric conversion performance of the aforementioned thermoelectric conversion element does not easily change when it is bent and used. Attached Figure Description

[0012] [ Figure 1 ] Figure 1 A plan view illustrating an example of an embodiment of the thermoelectric conversion element.

[0013] [ Figure 2 ] Figure 2 To be Figure 1 The image shows a cross-sectional view of the II-II line as a thermoelectric conversion element with a cut-off wire.

[0014] [ Figure 3 ] Figure 3 A diagram used to schematically illustrate the physics related to the bending of laminates.

[0015] [ Figure 4 ] Figure 4 This is a cross-sectional view of the thermoelectric conversion element involved in the reference example.

[0016] [ Figure 5 ] Figure 5 To show Figure 1 The graph shows the relationship between the magnetization of the thermoelectric conversion section of the thermoelectric conversion element and the external magnetic field.

[0017] [ Figure 6 ] Figure 6 This is a cross-sectional view illustrating another example of an embodiment of the thermoelectric conversion element.

[0018] [ Figure 7 ] Figure 7 A perspective view illustrating an example of an embodiment of a thermoelectric conversion device. Detailed Implementation

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the following description is illustrative of the present invention, and the present invention is not limited to the following embodiments.

[0020] like Figure 1 and Figure 2 As shown, the thermoelectric conversion element 1a includes a first sheet 10, a thermoelectric conversion section 30, and a second sheet 20. The first sheet 10, the thermoelectric conversion section 30, and the second sheet 20 are arranged in the thickness direction (Z-axis direction) of the first sheet 10 in the following order: first sheet 10, thermoelectric conversion section 30, and second sheet 20. The thermoelectric conversion section 30 includes a magnetic material. In the figures, the X-axis, Y-axis, and Z-axis are orthogonal to each other.

[0021] When a thermoelectric conversion element made of a magnetic material is bent, if deformation occurs in the magnetic material along with the bending of the thermoelectric conversion element, the properties of the magnetic material may change due to the magnetoelastic effect. In particular, if the amount of deformation of the magnetic material increases, the magnetoelastic effect also increases, and the properties of the magnetic material may change significantly.

[0022] like Figure 3 As shown, consider the nth layer ( Figure 3 In a laminate L (n=3), a bending moment M is applied. Here, the direction perpendicular to one of the principal faces of the laminate L is defined as the y-axis, and the position of this principal face is defined as y=0. In the laminate L, the neutral axis N exists at the position y=λ. Figure 3 As shown, the laminate L is bent with a radius of curvature ρ by applying compressive stress to the principal surface corresponding to y=0. In this case, the strain ε and stress σ at any position on the y-axis are represented by the following equations (1) and (2), respectively. In equation (2), E is the Young's modulus of the object.

[0023] ε = (y - λ) / ρ Equation (1) σ = E(y-λ) / ρ Equation (2) The position λ of the neutral axis N is represented by the following equation (3). In equation (3), E i Let h be the Young's modulus of the i-th layer starting from the layer that becomes the principal plane of y=0 (i=1). i h is the maximum value of the y-coordinate in the i-th layer. i-1 t represents the maximum value of the y-coordinate in the (i-1)th layer. i Let h0 be the thickness of the i-th layer. Where h0 = 0.

[0024] [Formula 1] In equation (2), positive stress σ corresponds to tensile stress, and negative stress σ corresponds to compressive stress. As shown in equations (1) and (2), the larger the absolute value of y-λ, the larger the absolute values ​​of strain and stress at that location. Therefore, it can be understood that the bending moment M causes large strain and large stress to be generated in the part near the outermost surface of the laminate L.

[0025] Figure 4 This is a cross-sectional view of the thermoelectric conversion element 1x according to the reference example. Except for lacking the second sheet 20 and the adhesive layer 40 described later, the thermoelectric conversion element 1x is constructed similarly to the thermoelectric conversion element 1a. In the thermoelectric conversion element 1x, the thermoelectric conversion portion 30, which includes the magnetic material, is arranged as the outermost surface of the thermoelectric conversion element 1x. Therefore, if the thermoelectric conversion element 1x is bent, large strain and stress are easily generated in the thermoelectric conversion portion 30, and the properties of the magnetic material may change significantly. Consequently, the thermoelectric conversion performance of the thermoelectric conversion element 1x is easily reduced.

[0026] On the other hand, such as Figure 2 As shown, in the thermoelectric conversion element 1a, the thermoelectric conversion section 30 is disposed between the first sheet 10 and the second sheet 20 in the thickness direction (Z-axis direction) of the first sheet 10, and is positioned away from the outermost surface of the thermoelectric conversion element 1a. Therefore, even if the thermoelectric conversion element 1a is bent, large strain and stress are not easily generated in the thermoelectric conversion section 30, and the properties of the magnetic material are not easily changed. Thus, even if the thermoelectric conversion element 1a is bent, the thermoelectric conversion performance of the thermoelectric conversion element 1a is not easily changed.

[0027] The arithmetic strain generated when the thermoelectric conversion element 1a is bent is not limited to a specific value. For example, the absolute value of the arithmetic strain in the thermoelectric conversion section 30 when the thermoelectric conversion element 1a is bent with a radius of curvature of 15 mm is |ε 15 |Not limited to specific values. Absolute value|ε 15 For example, 1.5 × 10 -3 In this case, the properties of the magnetic material included in the thermoelectric conversion section 30 are less likely to change, and even if the thermoelectric conversion element 1a is bent, the thermoelectric conversion performance of the thermoelectric conversion element 1a is less likely to change.

[0028] Absolute value | ε 15 | Can be 1.4×10 -3 The following can be 1.2 × 10 -3 The following can be 1.0×10 -3 The following can be 5.0×10 -4 The following can be 2.0×10 -4 The following can be 1.0×10 -4The following can be 5.0×10 -5 Below. Absolute value |ε 15 | can be 0.

[0029] like Figure 2 As shown, the thermoelectric conversion section 30 is disposed away from the outermost surfaces of both sides of the thermoelectric conversion element 1a in the thickness direction of the first sheet 10. Regarding the position of the thermoelectric conversion section 30 in the thickness direction of the first sheet 10, it is not limited to a specific position as long as the first sheet 10, the thermoelectric conversion section 30, and the second sheet are arranged in this order. For example, the thermoelectric conversion section 30 is disposed in the thickness direction of the first sheet 10 at or near the neutral axis N of the thermoelectric conversion element 1a, or at a position separated from the neutral axis N by a first distance d1. The ratio of the first distance d1 to the thickness t of the thermoelectric conversion element 1a, d1 / t, is 0.45 or less. The first distance d1 is the shortest distance between the neutral axis N in the thickness direction of the first sheet 10 and the thermoelectric conversion section 30. With this configuration, the thermoelectric conversion section 30 is located on or near the neutral axis N, making it less prone to large stresses and strains even when the thermoelectric conversion element 1a is bent. Therefore, the thermoelectric conversion performance of the thermoelectric conversion element 1a is less prone to change.

[0030] The ratio d1 / t can be below 0.43, below 0.40, below 0.38, below 0.35, below 0.30, or below 0.25.

[0031] As shown in equation (3), the position of the neutral axis N in the laminate L is determined based on the Young's modulus and thickness of each layer. Therefore, the position of the neutral axis of the thermoelectric conversion element 1a is affected by the Young's modulus and thickness of the first sheet 10 and the second sheet 20.

[0032] In thermoelectric conversion element 1a, the product E in the second sheet 20 20 t 20 2 Relative to the product E in the first sheet 10 10 t 10 2 The ratio of E 20 t 20 2 / E 10 t 10 2 Not limited to a specific value. Product E 10 t 10 2 The Young's modulus E of the first sheet 10 10 With the square of the thickness t 10 2 The product of E 20 t 20 2 The Young's modulus E of the second sheet 2020 With the square of the thickness t 20 2 The product of. (Compared to E) 20 t 20 2 / E 10 t 10 2 It can be, for example, 0.001~2.0, 0.002~2.0, 0.01~2.0, 0.05~2.0, 0.1~2.0, 0.2~2.0, 0.5~2.0, 0.6~1.5, 0.8~1.2, or 0.9~1.1.

[0033] The first sheet 10 contains E 10 t 10 2 Not limited to a specific value. Product E 10 t 10 2 For example, 1×10 5 ~1×10 10 MPa·(μm) 2 In this case, the thermoelectric conversion element 1a is easily bent, and the thermoelectric conversion element 1a easily possesses the desired strength. (E) 10 t 10 2 It can be 8×10 5 ~5×10 9 MPa·(μm) 2 Or 4.8×10 6 ~1.12×10 8 MPa·(μm) 2 .

[0034] The product E in the second sheet 20 20 t 20 2 Not limited to a specific value. Product E 20 t 20 2 For example, 1×10 4 ~1×10 10 MPa·(μm) 2 In this case, the thermoelectric conversion element 1a is easily bent, and the thermoelectric conversion element 1a easily possesses the desired strength. (E) 20 t 20 2 It can be 5×10 4 ~1×10 10 MPa·(μm) 2 1×10 5 ~1×10 10 MPa·(μm) 2 8×105 ~5×10 9 MPa·(μm) 2 or 4.8×10 6 ~1.12×10 8 MPa·(μm) 2 .

[0035] Young's modulus E of the first sheet 10 10 Not limited to a specific value. Young's modulus E 10 It can be, for example, 1×10 3 ~1×10 5 MPa, 2×10 3 ~2×10 4 MPa or 3×10 3 ~5×10 3 MPa. Young's modulus E of the second sheet 20. 20 Not limited to a specific value. Young's modulus E 20 It can be, for example, 1×10 3 ~1×10 5 MPa, 2×10 3 ~2×10 4 MPa or 3×10 3 ~5×10 3 MPa.

[0036] The thickness t of the first sheet 10 10 Not limited to a specific value. Thickness t 10 The thickness can be, for example, 10~1000μm, 20~500μm, or 40~150μm. The thickness t of the second sheet 20... 20 Not limited to a specific value. Thickness t 20 It can be, for example, 1~1000μm, 5~1000μm, 10~1000μm, 20~500μm, or 40~150μm.

[0037] The materials forming the first sheet 10 and the second sheet 20 are not limited to specific materials. The first sheet 10 and the second sheet 20 may contain, for example, organic materials. In this case, the thermoelectric conversion element 1a is easily bent and can be made lightweight. Examples of organic materials are organic polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), acrylic resin (PMMA), epoxy resin, polycarbonate (PC), polyimide (PI), and cyclic olefin polymers (COP).

[0038] Young's modulus E of thermoelectric conversion unit 30 30Not limited to a specific value. As shown in equation (2), the absolute value of the stress σ generated in the thermoelectric conversion section 30 when the thermoelectric conversion element 1a is bent is related to the Young's modulus E of the thermoelectric conversion section 30. 30 Proportional. Young's modulus E 30 For example, below 300 GPa. In this case, the absolute value of the stress σ generated in the thermoelectric conversion section 30 when the thermoelectric conversion element 1a is bent tends to decrease, and the thermoelectric conversion performance of the thermoelectric conversion element 1a is less prone to change. Young's modulus E 30 It can be 10~250GPa or 50~200GPa.

[0039] The thickness t of the thermoelectric conversion section 30 30 Not limited to a specific value. Thickness t 30 For example, the thickness is below 1 μm. In this case, the thermoelectric conversion section 30 has a relatively small impact on the determination of the neutral axis in the thermoelectric conversion element 1a. Therefore, in order to adjust the position of the neutral axis, only the first sheet 10 and the second sheet 20 need to be considered, making the design of the thermoelectric conversion element 1a easier. Thickness t 30 It can be 0.01~0.5μm or 0.02~0.15μm.

[0040] The rectangularity ratio S0 of the thermoelectric conversion section 30 is not limited to a specific value. The rectangularity ratio S0 is the ratio of remanent magnetization Mr to saturation magnetization Ms in the M-H curve, Mr / Ms. The rectangularity ratio S0 of the thermoelectric conversion section 30 is, for example, 80% or more. As a result, the thermoelectric conversion element 1a can more easily achieve the desired thermoelectric conversion performance. The rectangularity ratio S0 can be 85% or more, 90% or more, or 95% or more. The rectangularity ratio S0 is determined when the thermoelectric conversion element 1a is arranged on a flat surface.

[0041] The rate of change R of the rectangularity ratio of thermoelectric conversion element 1a 15 Not limited to a specific value. Rate of change R 15 It is represented by the following equation (4). In equation (4), S 15 The rectangular ratio of the thermoelectric conversion section 30 is determined when the thermoelectric conversion element 1a is bent with a radius of curvature of 15 mm.

[0042] rate of change R 15 =(S0-S 15 Formula (4) / S0 rate of change R 15 For example, below 0.15, the expected value is below 0.12, the more expected value is below 0.10, the further expected value is below 0.07, and the special expected value is below 0.05. Rate of change R 15 It can be 0.

[0043] The thermoelectric conversion section 30 generates a thermoelectric electromotive force, for example, in a direction perpendicular to the temperature gradient. With this configuration, for example, in the thermoelectric conversion element 1a, when a temperature gradient is generated in the thickness direction of the first sheet 10, a thermoelectric electromotive force is generated in the direction along the main surface of the first sheet 10 of the thermoelectric conversion section 30. Therefore, by adjusting the shape and size of the thermoelectric conversion section 30 in a plane parallel to the main surface of the first sheet 10, a large thermoelectric electromotive force can be easily generated in the thermoelectric conversion element 1a.

[0044] In the thermoelectric conversion unit 30, for example, a thermoelectric electromotive force is generated using the anomalous Nernst effect. In this case, the thermoelectric conversion element 1a can easily exhibit high thermoelectric conversion performance. The thermoelectric conversion unit 30 can also be configured to generate a thermoelectric electromotive force using the spin Seebeck effect and the inverse spin Hall effect.

[0045] like Figure 1 As shown, the thermoelectric conversion section 30 is formed, for example, a thin wire 31. With this configuration, for example, by magnetizing the thin wire 31 in the width direction, a temperature gradient is generated in the thickness direction of the first sheet 10, enabling the generation of a thermoelectric electromotive force (TMF) associated with the anomalous Nernst effect in the length direction of the thin wire 31. In this case, a TMF corresponding to the length of the thin wire 31 can be generated, thereby making it easier for the thermoelectric conversion element 1a to achieve the desired thermoelectric conversion performance.

[0046] The width of the fine wire 31 is not limited to a specific value. For example, the width of the fine wire 31 is 500 μm or less. This reduces the amount of material used in the fine wire 31, thereby easily reducing the manufacturing cost of the thermoelectric conversion element 1a. Furthermore, multiple fine wires 31 can be easily arranged in the thermoelectric conversion element 1a, making it easier for the thermoelectric conversion element 1a to achieve the desired thermoelectric conversion performance. For example, the width of the fine wire 31 is 1 μm or more. This reduces the likelihood of wire breakage in the fine wire 31, and the thermoelectric conversion element 1a tends to have high durability.

[0047] The width of the thin line 31 may be included in any of the ranges defined by any combination of a lower limit value of 1μm, 2μm, 5μm, 10μm, 20μm and 30μm and an upper limit value of 500μm, 400μm, 300μm, 200μm, 100μm and 50μm.

[0048] Figure 5 A graph showing the relationship between the magnetization of the thermoelectric conversion unit 30 and the external magnetic field. Figure 5 In the diagram, the solid line graph shows the relationship between the magnetization of the thermoelectric conversion section 30 along the width direction (X-axis) of the thin wire 31 and the external magnetic field. The dashed line graph shows the relationship between the magnetization of the thermoelectric conversion section 30 along the length direction (Y-axis) of the thin wire 31 and the external magnetic field. Figure 5As shown, the magnetic properties of the thermoelectric conversion section 30 exhibit significant anisotropy in both the length and width directions of the thin wire 31. Due to this significant anisotropy, a difficult-to-magnetize axis is generated in the thermoelectric conversion section 30 along the length of the thin wire 31, while an easy-to-magnetize axis is generated along the width direction of the thin wire 31. Consequently, the thermoelectric conversion section 30 readily exhibits stable behavior in response to external magnetic fields, and the thermoelectric conversion element 1a more easily achieves the desired thermoelectric conversion performance. For example, the thermoelectric conversion section 30 has an easy-to-magnetize axis in the width direction of the thin wire 31.

[0049] The magnetic material included in the thermoelectric conversion section 30 is not limited to a specific material. This magnetic material may include, for example, a material exhibiting an anomalous Nernst effect. The material exhibiting an anomalous Nernst effect is not limited to a specific material. For example, a material exhibiting an anomalous Nernst effect has a magnetic material with a density of 5 × 10⁻⁶. -3 The material is a magnetic material with a saturation magnetic susceptibility of T or higher, or a material whose band structure has a Weyl point near the Fermi level. The magnetic material may be a ferrimagnetic material. As for the thermoelectric conversion section 30, the material exhibiting the anomalous Nernst effect is, for example, a material containing at least one of the following (i), (ii), (iii), (iv) and (v).

[0050] (i) having a stoichiometric composition represented by Fe3X (ii) Non-stoichiometric substances whose composition ratio of Fe to X deviates from that in (i) above. (iii) A substance obtained by replacing part of the Fe site of the substance in (i) above or part of the Fe site of the substance in (ii) above with a typical metallic element or transition element other than X. (iv) Possessing Fe3M1 1-x M2 x (0 < x < 1) represents a substance whose composition, M1, and M2 are typical elements that are different from each other. (v) A substance obtained by replacing part of the Fe site of the substance in (i) with a transition element other than X, or by replacing part of the X site of the substance in (i) with a typical metallic element other than X. In the substances described in (i) to (v) above, X is a typical element or a transition element. X is, for example, Al, Ga, Ge, Sn, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Sc, Ni, Mn, or Co. In (iv) above, regarding the combination of M1 and M2, as long as M1 and M2 are different typical elements from each other, the combination is not limited to a specific combination. In (iv) above, the combination of M1 and M2 is, for example, Ga and Al, Si and Al, or Ga and B.

[0051] Regarding the thermoelectric conversion section 30, the material exhibiting the anomalous Nernst effect may include Co2MnGa or Mn3Sn.

[0052] like Figure 2 As shown, the thermoelectric conversion element 1a includes, for example, an adhesive layer 40. The adhesive layer 40 is located between the first sheet 10 and the second sheet 20 in the thickness direction of the first sheet 10, and bonds the first sheet 10 and the second sheet 20 together.

[0053] The adhesive forming the adhesive layer 40 is not limited to a specific adhesive. The adhesive can be a thermosetting adhesive or an active energy radiation-cured adhesive. Active energy radiation-cured adhesives can be ultraviolet-cured adhesives or visible light-cured adhesives. Examples of thermosetting adhesives include epoxy resin-based adhesives, phenolic resin-based adhesives, polyurethane-based adhesives, and cyanoacrylate-based adhesives. Examples of active energy radiation-cured adhesives include acrylic adhesives, silicone adhesives, epoxy adhesives, and urethane-based adhesives.

[0054] The thickness t of the adhesive layer 40 40 Not limited to a specific value. Thickness t 40 For example, a thickness of 5 μm or less. In this case, the adhesive layer 40 has a relatively small impact on the determination of the neutral axis in the thermoelectric conversion element 1a. Therefore, to adjust the position of the neutral axis, only the first sheet 10 and the second sheet 20 need to be considered, making the design of the thermoelectric conversion element 1a easier. Thickness t 40 It can be 0.2~3μm or 0.8~1.5μm.

[0055] like Figure 1 As shown, the thermoelectric conversion section 30 has, for example, multiple fine lines 31. The thermoelectric conversion element 1a has, for example, a zigzag pattern including the thermoelectric conversion section 30. With this configuration, the total length of the fine lines 31 included in the thermoelectric conversion element 1a tends to increase. The greater the total length of the fine lines 31, the easier it is for the electromotive force generated in the length direction of the fine lines 31 by utilizing the temperature gradient in the thickness direction of the first sheet 10 to increase. Therefore, by having the thermoelectric conversion element 1a have a zigzag pattern including the thermoelectric conversion section 30, the electromotive force generated in the thermoelectric conversion element 1a tends to increase.

[0056] like Figure 1 and Figure 2As shown, the thermoelectric conversion element 1a also includes, for example, wiring 32. Wiring 32 electrically connects the thin wires 31 to each other. For example, multiple thin wires 31 in the thermoelectric conversion section 30 are electrically connected in series via wiring 32. Wiring 32 has, for example, multiple wirings 33. The multiple thin wires 31 and the multiple wirings 33 are electrically connected in series. With this configuration, even if the area of ​​the surface on which the multiple thin wires 31 and the multiple wirings 33 are arranged is small, it is easy to generate a large electromotive force in the thermoelectric conversion element 1a.

[0057] Wiring 32 can be formed from a metallic element or an alloy.

[0058] Multiple fine lines 31 and multiple wirings 33 are arranged in a zigzag pattern, for example, as described above. This forms a conductive path 35. For example, the electromotive force generated in the thermoelectric conversion element 1a can be extracted to the outside by connecting external wirings to one end and the other end of the conductive path 35. Alternatively, by applying a voltage between one end and the other end of the conductive path 35, heat flow can be generated in the thickness direction of the sheet 10.

[0059] Multiple thin lines 31 are spaced apart at predetermined intervals in the X-axis direction and arranged parallel to each other. Wiring 32 electrically connects, for example, one end of a thin line 31 in the Y-axis direction and the other end of another thin line 31 adjacent to that thin line 31 in the Y-axis direction. The ends of the multiple thin lines 31 in the Y-axis direction are located on the same side of the thin line 31 in the Y-axis direction, and the other ends of the multiple thin lines 32 in the Y-axis direction are located on the opposite side of the ends of the thin lines 31 in the Y-axis direction.

[0060] The thickness of wiring 32 is not limited to a specific value. Its thickness may, for example, be included in any of the ranges defined by any combination of a lower limit value of 5nm, 10nm, 20nm, 30nm and 50nm and an upper limit value of 1000nm, 750nm, 500nm, 400nm, 300nm and 200nm.

[0061] The width of wiring 32 is not limited to a specific value. Its width can be included in any of the following ranges: any lower limit value of 0.1μm, 0.5μm, 1μm, 2μm, 5μm, 10μm, 20μm and 30μm, and any upper limit value of 500μm, 400μm, 300μm, 200μm, 100μm and 50μm.

[0062] An example of a method for manufacturing a thermoelectric conversion element 1a is shown. The thermoelectric conversion element 1a is manufactured by, for example, methods including (I) and (II) below.

[0063] (I) A thermoelectric conversion section 30 is formed on one main surface of the first sheet 10.

[0064] (II) Apply an adhesive to at least one of the first sheet 10 and the second sheet 20, and cure the adhesive to bond a main surface of the first sheet 10 to the second sheet 20.

[0065] In (I), for example, a film of the precursor of the thermoelectric conversion section 30 is formed on one main surface of the first sheet 10 using methods such as sputtering, chemical vapor deposition (CVD), pulsed laser deposition (PLD), ion plating, and coating. Next, for example, a photoresist is coated onto the film, a photomask is placed on the film, exposure is performed, and then wet etching is performed. This forms multiple fine lines of the precursor of the thermoelectric conversion section 30 arranged at predetermined intervals. Next, a film of the precursor of the wiring 32 is formed on one main surface of the first sheet 10 using methods such as sputtering, CVD, PLD, ion plating, and coating. Next, a photoresist is coated onto the film of the precursor of the wiring 32, a photomask is placed on the film of the precursor of the wiring 32, exposure is performed, and then wet etching is performed. This results in the wiring 32, where the fine lines of the precursor of the thermoelectric conversion section 30 are electrically connected to each other.

[0066] In (I), a prescribed heat treatment is performed as needed. The ambient temperature of the first sheet 10 and the precursor of the thermoelectric conversion section 30 during the heat treatment is, for example, 50°C or higher. Therefore, from the viewpoint of thermoelectric conversion performance, it is easy to adjust the internal stress of the thermoelectric conversion section 30 to the desired state. The ambient temperature of the first sheet 10 and the precursor of the thermoelectric conversion section 30 during the heat treatment can be 100°C or higher, 150°C or higher, or 200°C or higher. This ambient temperature is, for example, 300°C or lower.

[0067] During the heat treatment, the time during which the ambient temperature of the first sheet 10 is maintained above 50°C is not limited to a specific value. This time is, for example, more than 10 minutes and less than 3 hours.

[0068] After heat treatment, the precursor of the thermoelectric conversion unit 30 is magnetized to obtain the thermoelectric conversion unit 30.

[0069] Next, proceeding to (II), an adhesive is applied to at least one of the first sheet 10 and the second sheet 20. The adhesive is applied by, for example, spin coating. Next, one main surface of the first sheet 10 is bonded to one main surface of the second sheet 20 using the adhesive. Next, the adhesive is cured by heating it or by irradiating it with active energy rays such as ultraviolet light, resulting in an adhesive layer 40. For example, the thermoelectric conversion element 1a is manufactured in this manner.

[0070] Thermoelectric conversion element 1a can be as follows Figure 6The thermoelectric conversion element 1b shown is modified as described above. The thermoelectric conversion element 1b is configured identically to the thermoelectric conversion element 1a, except where specifically described. The same reference numerals are used for the constituent elements of the thermoelectric conversion element 1b that are identical or corresponding to those of the thermoelectric conversion element 1a, and detailed descriptions are omitted. The description of the thermoelectric conversion element 1a also applies to the thermoelectric conversion element 1b, provided there is no technical contradiction.

[0071] like Figure 6 As shown, in the thermoelectric conversion element 1b, the adhesive layer 40 is omitted, and the second sheet 20 is in contact with the thermoelectric conversion section 30. With this configuration, even if the thermoelectric conversion element 1b is bent, its thermoelectric conversion performance is not easily affected. A portion of the second sheet 20, for example, is in contact with one of the main surfaces of the first sheet 10.

[0072] Regarding the thermoelectric conversion element 1b, for example, it can be manufactured by the following method: instead of the process described in (II) above, a precursor of a fluid second sheet 20 is coated to a predetermined thickness on a main surface of a first sheet 10 on which the thermoelectric conversion section 30 is formed, and the precursor is cured to obtain the second sheet 20. Examples of precursors for the second sheet 20 are acrylic resin and epoxy resin precursors. The curing of the precursor of the second sheet 20 can be carried out by irradiation or heating with active energy rays such as ultraviolet light.

[0073] The thermoelectric conversion element 1a or 1b can be provided, for example, together with an adhesive layer. In this case, the adhesive layer is in contact with the first sheet 10 or the second sheet 20, and the first sheet 10 or the second sheet 20 is disposed between the thermoelectric conversion part 30 and the adhesive layer in the thickness direction of the first sheet 10. Thus, the adhesive layer can be pressed against the article, thereby mounting the thermoelectric conversion element 1a to the article.

[0074] The adhesive layer may include, for example, rubber-based adhesives, acrylic adhesives, silicone adhesives, or urethane adhesives. The thermoelectric conversion element 1a may also be provided together with the adhesive layer and a release liner. In this case, the release liner covers the adhesive layer. Typically, the release liner is a film that maintains the adhesive strength of the adhesive layer when it is covered and can be easily peeled off from the adhesive layer. The release liner is, for example, a film made of polyester resin such as PET. The adhesive layer can be exposed by peeling off the release liner, and the thermoelectric conversion element 100 can be attached to the article.

[0075] like Figure 7As shown, for example, a thermoelectric conversion device 3 equipped with a thermoelectric conversion element 1a can be provided. This thermoelectric conversion device 3 is, for example, a sensor for detecting heat in the object 5. For example, if a temperature gradient is generated in the thickness direction of the first sheet 10, an electromotive force is generated in the length direction of the wire 31. The thermoelectric conversion device 3 can sense heat by processing the electrical signal output to the outside of the thermoelectric conversion element 1a based on this electromotive force. The thermoelectric conversion device 3 may also include a signal processing device 2, for example. In the signal processing device 2, the electrical signal output to the outside of the thermoelectric conversion element 1a is processed. The thermoelectric conversion device 3 may also be configured as a device other than a sensor. The thermoelectric conversion device 3 may also include a thermoelectric conversion element 1b.

[0076] like Figure 7 As shown, the thermoelectric conversion element 1a is arranged along a curved surface. Even when the thermoelectric conversion element 1a is bent in this way, it is easy for the thermoelectric conversion element 1a to perform the desired thermoelectric conversion performance, and the thermoelectric conversion device 3 is also easy to have the desired performance. The curved surface can be, for example, a cylindrical surface, a spherical surface, other quadratic surfaces, or surfaces other than quadratic surfaces.

[0077] Example The present invention will now be described in more detail through embodiments. However, the present invention is not limited to the following embodiments. First, the evaluation method of the embodiments will be described.

[0078] <Example 1> A thin film with a thickness of 0.1 μm was formed on a first sheet of polyethylene terephthalate (PET) film with a thickness of 50 μm using DC magnetron sputtering with a target containing Fe and Ga. Argon gas was supplied as the process gas at a pressure of 0.1 Pa during DC magnetron sputtering. The Fe content to Ga content ratio in the target was set to 3:1 (atomic ratio). The temperature around the first sheet was adjusted to 100°C. The first sheet with the formed film was then heat-treated at 150°C for 30 minutes. Next, a photoresist was coated onto the film, a photomask was placed on top of the film, exposure was performed, and then wet etching was carried out. This resulted in 115 FeGa-containing fine lines arranged at predetermined intervals. Each FeGa-containing fine line had a width of 40 μm and a length of 1.5 cm. Then, using a Cu-containing target, a Cu thin film with a thickness of 0.1 μm is formed on the first sheet by DC magnetron sputtering. A photoresist is coated onto the Cu thin film, a photomask is placed on top of the Cu thin film, exposure is performed, and then wet etching is carried out. This forms a Cu-containing fine line with a width of 40 μm. Adjacent pairs of FeGa-containing fine lines are electrically connected to each other through the Cu-containing fine lines, forming a conductive path that constitutes a zigzag pattern.

[0079] Using an electromagnet with a central magnetic flux density of 0.5T, the FeGa-containing fine wires are magnetized in a width direction parallel to the main surface of the first sheet and perpendicular to the length direction of the FeGa-containing fine wires. Next, an epoxy-based thermosetting adhesive is applied to the main surface of a second sheet, which is another PET film with a thickness of 50 μm, and this main surface is bonded to the main surface of the first sheet where the FeGa-containing fine wires are formed. In this state, the adhesive is heated at 120°C for 1 hour to cure the adhesive, resulting in an adhesive layer. The thickness of the adhesive layer is 1 μm. This process yields the thermoelectric conversion element according to Example 1.

[0080] <Example 2> Except for the aspects described below, the thermoelectric conversion element involved in Example 2 was obtained by operating in the same manner as in Example 1. A polyimide (PI) sheet with a thickness of 50 μm was used as the second sheet instead of a PET film.

[0081] <Example 3> Except as described below, the thermoelectric conversion element according to Example 3 was obtained by operating in the same manner as in Example 1. As a precursor for the second sheet, epoxy photoresist SU-8 manufactured by Nippon Kayaku Co., Ltd. was used. After magnetizing a fine wire containing FeGa, epoxy photoresist SU-8 was spin-coated onto the main surface of the first sheet to form a coating film at a predetermined thickness. The coating film was cured by irradiating it with ultraviolet light containing light with a wavelength of 365 nm, resulting in a second sheet containing epoxy resin. The thickness of the second sheet was 20 μm. This operation yielded the thermoelectric conversion element according to Example 3.

[0082] <Example 4> Except for the aspects described below, the thermoelectric conversion element involved in Example 4 was obtained by operating in the same manner as in Example 3. An epoxy photoresist SU-8 coating was formed on the main surface of the first sheet by spin coating with the second sheet having a thickness of 10 μm.

[0083] <Example 5> Except for the aspects described below, the thermoelectric conversion element of Example 5 was obtained by operating in the same manner as in Example 3. An epoxy photoresist SU-8 coating was formed on the main surface of the first sheet by spin coating with the second sheet having a thickness of 5 μm.

[0084] <Example 6> Except for the aspects described below, the thermoelectric conversion element of Example 6 was obtained by operating in the same manner as in Example 3. An epoxy photoresist SU-8 coating was formed on the main surface of the first sheet by spin coating with the second sheet having a thickness of 2 μm.

[0085] <Comparative Example 1> Except for not applying the adhesive and bonding the second sheet, the thermoelectric conversion element involved in Comparative Example 1 was obtained by operating in the same manner as in Example 1.

[0086] [Young's modulus of sheet material] Test pieces were prepared using cured PET film, PI film, and SU-8 coatings used in the various examples and comparative examples. The tensile modulus (Young's modulus) of these sheets was determined according to Japanese Industrial Standard (JIS) K7161-1. A Minebea Inc. TCM-1kNB testing machine was used for this determination. The test speed was set to 300 mm / min. The results are shown in Table 1.

[0087] [Young's modulus of fine wires containing FeGa] The tensile modulus (Young's modulus) of the materials forming FeGa-containing fine wires in the thermoelectric conversion elements involved in each example and comparative example was determined using a Hysitron TriboIndenter (TI-950) nanoindenter according to the nanoindentation method. In this determination, a diamond triangular pyramidal Berkovich indenter was pressed into the sample. The dihedral angle of this indenter was 115°. The results are shown in Table 1.

[0088] [Strain and stress during bending] The arithmetic strain ε in the FeGa-containing wire when each thermoelectric conversion element is bent with a radius of curvature of 15 mm is calculated according to the above formulas (1) to (3). 15 The absolute value and stress σ 15 Furthermore, the ratio of the distance (first distance) between the neutral axis in the thickness direction of the first sheet and the FeGa-containing fine wire to the thickness of each thermoelectric conversion element was calculated. The results are shown in Table 1. It should be noted that, according to this calculation, in each embodiment, the FeGa-containing fine wire exists in the thickness direction of the first sheet at a distance from the neutral axis equivalent to 45% of the thickness of the thermoelectric conversion element.

[0089] [Magnetic properties] The magnetic properties of the FeGa-containing fine wires in the thermoelectric conversion elements of each embodiment and comparative example were measured using the PPMS-versalab physical property measurement device from Qantum Design. In this measurement, a 2mm square sample was prepared by cutting a portion of the module with the conductive path from each embodiment and comparative example. Furthermore, a vibrating sample magnetometer (VSM) was used to scan a magnetic field of ±800 kA / m in a direction parallel to the magnetization direction of the magnetized FeGa-containing fine wire. Under a temperature of 300 K, considering the thickness of the FeGa-containing fine wire and the area of ​​the FeGa-containing fine wire in the measurement sample, the M-H curve was obtained. The ratio Mr / Ms, where the magnetization Ms is ±800 kA / m and the magnetization Mr is 0 kA / m during the magnetic field scan, was determined as the rectangle ratio S0 or S. 15 The rectangle ratio S0 is determined when the sample is positioned on a flat surface. 15 The test sample was determined under the condition that the first sheet was subjected to compressive stress and had a radius of curvature of 15 mm. The rectangle ratio S0 and S were determined according to equation (4). 15 Determine the rate of change R 15 The results are shown in Table 1.

[0090] As shown in Table 1, compared with the thermoelectric conversion element involved in Comparative Example 1, the arithmetic strain ε in the FeGa-containing wire when the thermoelectric conversion element involved in each embodiment is bent with a radius of curvature of 15 mm is... 15 The absolute value and stress σ 15 Small. Furthermore, the rate of change R of the rectangularity ratio of the thermoelectric conversion element involved in each embodiment is small. 15 The rate of change R of the rectangularity of the thermoelectric conversion element involved in Comparative Example 1 is less than that of the element involved in Comparative Example 1. 15 By constructing the thermoelectric conversion element by arranging fine wires containing FeGa between the first and second sheets, it is expected that the thermoelectric conversion performance will not easily change even if the thermoelectric conversion element is bent.

[0091] [Table 1] A first aspect of the present invention provides a thermoelectric conversion element comprising: First sheet material Thermoelectric conversion unit, and Second sheet, The aforementioned first sheet, the aforementioned thermoelectric conversion unit, and the aforementioned second sheet are arranged in the thickness direction of the aforementioned first sheet in the following order: the aforementioned first sheet, the aforementioned thermoelectric conversion unit, and the aforementioned second sheet. The aforementioned thermoelectric conversion section includes a magnetic material.

[0092] A second aspect of the present invention provides a thermoelectric conversion element according to the first aspect, wherein the absolute value of the arithmetic strain in the thermoelectric conversion section when the aforementioned thermoelectric conversion element is bent with a radius of curvature of 15 mm is 1.5 × 10⁻⁶. -3 the following.

[0093] A third aspect of the present invention provides a thermoelectric conversion element according to the first aspect, wherein, When the aforementioned thermoelectric conversion element is bent with a radius of curvature of 15 mm, the absolute value of the arithmetic strain in the aforementioned thermoelectric conversion section is 1.0 × 10⁻⁶. -3 the following.

[0094] A fourth aspect of the present invention provides a thermoelectric conversion element according to any one of the first to third aspects, wherein, The aforementioned thermoelectric conversion section is located on the neutral axis of the aforementioned thermoelectric conversion element or at a position separated from the aforementioned neutral axis by a first distance in the thickness direction of the aforementioned first sheet. The ratio of the aforementioned first distance to the thickness of the aforementioned thermoelectric conversion element is 0.45 or less.

[0095] A fifth aspect of the present invention provides a thermoelectric conversion element according to the first or second aspect, wherein, The aforementioned thermoelectric conversion section is located on the neutral axis of the aforementioned thermoelectric conversion element or at a position separated from the aforementioned neutral axis by a first distance in the thickness direction of the aforementioned first sheet. The ratio of the aforementioned first distance to the thickness of the aforementioned thermoelectric conversion element is 0.25 or less.

[0096] The sixth aspect of the present invention provides a thermoelectric conversion element according to any one of the first to fifth aspects, wherein the aforementioned thermoelectric conversion section has a rectangularity ratio of 80% or more.

[0097] The seventh aspect of the present invention provides a thermoelectric conversion element according to any one of the first to sixth aspects, wherein the aforementioned first sheet and the aforementioned second sheet comprise organic materials.

[0098] The eighth aspect of the present invention provides a thermoelectric conversion element according to any one of the first to seventh aspects, wherein the aforementioned thermoelectric conversion part generates a thermoelectric electromotive force in a direction perpendicular to the temperature gradient.

[0099] The ninth aspect of the present invention provides a thermoelectric conversion element according to any one of the first to eighth aspects, wherein the aforementioned thermoelectric conversion section generates a thermoelectric electromotive force by utilizing the anomalous Nernst effect.

[0100] A tenth aspect of the present invention provides a thermoelectric conversion device having a thermoelectric conversion element according to any one of the first to ninth aspects.

[0101] The eleventh aspect of the present invention provides a thermoelectric conversion device according to the tenth aspect, wherein the aforementioned thermoelectric conversion element is arranged along a curved surface.

Claims

1. A thermoelectric conversion element, which comprises: First sheet material Thermoelectric conversion unit, and Second sheet, in, The first sheet, the thermoelectric conversion part, and the second sheet are arranged in the thickness direction of the first sheet in the order of the first sheet, the thermoelectric conversion part, and the second sheet. The thermoelectric conversion unit includes a magnetic material.

2. The thermoelectric conversion element as claimed in claim 1, wherein, The absolute value of the arithmetic strain in the thermoelectric conversion section when the thermoelectric conversion element is bent with a radius of curvature of 15 mm is 1.5 × 10⁻⁶. -3 the following.

3. The thermoelectric conversion element as described in claim 1, wherein, The absolute value of the arithmetic strain in the thermoelectric conversion section when the thermoelectric conversion element is bent with a radius of curvature of 15 mm is 1.0 × 10⁻⁶. -3 the following.

4. The thermoelectric conversion element as claimed in claim 1, wherein, The thermoelectric conversion section is located on the neutral axis of the thermoelectric conversion element or at a position separated from the neutral axis by a first distance in the thickness direction of the first sheet. The ratio of the first distance to the thickness of the thermoelectric conversion element is less than 0.

45.

5. The thermoelectric conversion element as claimed in claim 1, wherein, The thermoelectric conversion section is located on the neutral axis of the thermoelectric conversion element or at a position separated from the neutral axis by a first distance in the thickness direction of the first sheet. The ratio of the first distance to the thickness of the thermoelectric conversion element is less than 0.

25.

6. The thermoelectric conversion element as claimed in claim 1, wherein, The thermoelectric conversion section has a rectangularity ratio of over 80%.

7. The thermoelectric conversion element as claimed in claim 1, wherein, The first sheet and the second sheet contain organic materials.

8. The thermoelectric conversion element as claimed in claim 1, wherein, The thermoelectric conversion unit generates a thermoelectric electromotive force in a direction perpendicular to the temperature gradient.

9. The thermoelectric conversion element as claimed in claim 1, wherein, The thermoelectric conversion unit generates thermoelectric potential by utilizing the anomalous Nernst effect.

10. A thermoelectric conversion device comprising the thermoelectric conversion element according to any one of claims 1 to 9.

11. The thermoelectric conversion device as claimed in claim 10, wherein, The thermoelectric conversion element is arranged along the curved surface.

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