Thermoelectric conversion element

Abstract

A thermoelectric conversion element 1a comprises a substrate 10 and magnetic bodies 21. The magnetic bodies 21 are disposed on the substrate 10 and are ferromagnetic or antiferromagnetic. The ratio of the measured density of the magnetic bodies 21 to the theoretical density of the magnetic bodies 21 is 0.80 or more.

Description

thermoelectric conversion element

[0001] The present invention relates to a thermoelectric conversion element.

[0002] 2. Description of the Related Art Conventionally, thermoelectric conversion elements that utilize the magneto-thermoelectric effect have been known.

[0003] For example, Patent Document 1 describes a thermoelectric power generation device that utilizes the anomalous Nernst effect. The anomalous Nernst effect is a phenomenon in which, when a heat flow is passed through a magnetic material, a voltage is generated in a direction perpendicular to both the magnetization direction and the temperature gradient when a temperature difference occurs. The thermoelectric power generation device includes a substrate, a power generation body, and a connector. At least the surface layer of the substrate is made of MgO. The power generation body is made of multiple thin wires arranged parallel to each other along the surface of the substrate. Each thin wire is made of a ferromagnetic material and magnetized in the same direction. The connector is made of multiple thin wires arranged parallel to and between the thin wires of the power generation body. Each thin wire of the connector electrically connects one end of each thin wire of the power generation body to the other end of the adjacent thin wire on one side of each thin wire.

[0004] Patent Document 2 describes a thermoelectric conversion element having a thermoelectric mechanism that generates electromotive force by the anomalous Nernst effect. According to equation (1) in Patent Document 2, it can be understood that the Nernst coefficient Syx is proportional to the reciprocal of the electrical conductivity, i.e., the resistivity.

[0005] JP 2014-072256 A International Publication No. 2019 / 009308

[0006] According to the description in Patent Document 1, in order to form a crystal structure with a large magneto-thermoelectric effect, a substrate having at least a surface layer made of MgO is required. Thus, the technology described in Patent Document 1 requires a special substrate. Patent Document 1 does not specifically consider the issues that arise when a thermoelectric conversion element is fabricated using a non-special substrate, such as a substrate containing an organic material. Therefore, the present inventors attempted to fabricate a thermoelectric conversion element using a non-special substrate, such as a substrate containing an organic material.

[0007] According to the description in Patent Document 2, it is considered advantageous to increase the resistivity of the material when increasing the Nernst coefficient in a thermoelectric conversion element utilizing the magneto-thermoelectric effect. On the other hand, Patent Documents 1 and 2 do not specifically consider the problems associated with increasing the resistivity of the material. According to the study by the present inventors, it was found that increasing the resistivity of the material causes problems such as the generation of noise and a decrease in power generation output.

[0008] In view of these circumstances, the present invention provides an advantageous thermoelectric conversion element from the viewpoint of improving thermoelectric conversion performance even when a non-special substrate, such as a substrate containing an organic material, is used while maintaining a low resistivity of the magnetic material.

[0009] The present invention provides a thermoelectric conversion element comprising: a substrate; and a magnetic body having ferromagnetic or antiferromagnetic properties, the magnetic body being disposed on the substrate; wherein the ratio of the measured density of the magnetic body to the theoretical density of the magnetic body is 0.80 or more.

[0010] The above thermoelectric conversion element is advantageous in that it maintains the specific resistance of the magnetic material low and enhances the thermoelectric conversion performance even when a non-special substrate such as a substrate containing an organic material is used.

[0011] Fig. 1 is a perspective view showing an example of a thermoelectric conversion element according to the present invention, and Fig. 2 is a cross-sectional view of the thermoelectric conversion element taken along plane II shown in Fig. 1.

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0013] As shown in FIG. 1 , the thermoelectric conversion element 1a includes a substrate 10 and a magnetic material 21. The magnetic material 21 is disposed on the substrate 10 and has ferromagnetic or antiferromagnetic properties. The ratio D / D of the measured density D of the magnetic material 21 to the theoretical density D of the magnetic material 21 is 0.80 or greater. By adjusting the ratio D / D within this range, the thermoelectric conversion element 1a can easily improve its thermoelectric conversion performance while maintaining a low resistivity of the magnetic material 21. Maintaining a low resistivity of the magnetic material 21 can easily suppress noise generation in the thermoelectric conversion element 1a. In addition, the thermoelectric conversion element 1a can easily increase its power generation output. The theoretical density D and measured density D of the magnetic material 21 can be determined, for example, according to the method described in the Examples. In FIGS. 1 and 2 , the X-axis, Y-axis, and Z-axis are perpendicular to each other, and the Z-axis direction is the thickness direction of the substrate 10.

[0014] The ratio D / D in the magnetic body 21 may be 0.82 or more, 0.84 or more, 0.90 or more, 0.95 or more, or 1.00 or more. The ratio D / D in the magnetic body 21 is, for example, 1.1 or less.

[0015] The magnetic body 21 is not limited to a specific material as long as the ratio D / D0 of the magnetic body 21 is 0.80 or greater. For example, the magnetic body 21 generates an electromotive force in a direction perpendicular to the thickness direction of the substrate 10 when a temperature gradient ∇T occurs in the thickness direction (Z-axis direction) of the substrate 10. This eliminates the need to significantly adjust the thickness of the thermoelectric conversion element 1a to increase the power generated by the temperature gradient in the thermoelectric conversion element 1a, as in thermoelectric conversion elements utilizing the Seebeck effect. For example, by increasing the dimension of the magnetic body 21 in a specific direction along the main surface of the substrate 10, the power generated by the temperature gradient ∇T in the thermoelectric conversion element 1a can be increased. This facilitates the reduction of the thickness of the thermoelectric conversion element 1a.

[0016] The magnetic body 21 generates an electromotive force by, for example, the magneto-thermoelectric effect. The magneto-thermoelectric effect is, for example, the anomalous Nernst effect or the spin Seebeck effect. This makes it easy for the thermoelectric conversion element 1 a to generate a large amount of electric power due to a temperature gradient even if the thermoelectric conversion element 1 a is thin.

[0017] The magnetic body 21 includes, for example, a material that exhibits the anomalous Nernst effect. The material that exhibits the anomalous Nernst effect is not limited to a specific material. The material that exhibits the anomalous Nernst effect may be, for example, 5×10 -3 The magnetic material 21 is a magnetic material having a saturation magnetic susceptibility of 1000 kJ or more, or a material having a band structure with a Weyl point near the Fermi energy. The magnetic material 21 contains, as a material exhibiting the anomalous Nernst effect, at least one material selected from the group consisting of the following (i), (ii), (iii), (iv), and (v): (i) a stoichiometric material having a composition represented by Fe3X; (ii) an off-stoichiometric material in which the composition ratio of Fe to X deviates from that of the material (i) above; (iii) a material in which part of the Fe sites of the material (i) above or part of the Fe sites of the material (ii) above are substituted with a main group metal element or transition element other than X; (iv) Fe3M1 1-x M2 x (v) A substance having a composition expressed by (0<x<1), in which M1 and M2 are different typical group elements. (i) A substance in which a part of the Fe site of the substance (i) is substituted with a transition element other than X, and a part of the X site of the substance (i) is substituted with a typical metal element other than X.

[0018] In the above substances (i) to (v), 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 the above substance (iv), the combination of M1 and M2 is not limited to a specific combination as long as M1 and M2 are different typical elements. In the above substance (iv), the combination of M1 and M2 is, for example, Ga and Al, Si and Al, or Ga and B.

[0019] The magnetic body 21 may contain Co2MnGa or Mn3Sn as a material that exhibits the anomalous Nernst effect.

[0020] As shown in Figures 1 and 2, the magnetic body 21 is formed, for example, in the shape of a rectangular parallelepiped elongated in a specific direction (Y-axis direction) extending along the main surface of the substrate 10. The magnetic body 21 is magnetized, for example, in the negative direction of the X-axis. When a temperature gradient occurs in the thickness direction of the substrate 10 and a heat flow occurs in the positive direction of the Z-axis, the magneto-thermoelectric effect generates an electromotive force in the positive direction of the Y-axis, which is perpendicular to the Z-axis and X-axis. As described above, the dimension of the magnetic body 21 in the Y-axis direction is larger than the dimensions of the magnetic body 21 in the Z-axis and X-axis, and the electromotive force generated by the magneto-thermoelectric effect is likely to be large. Therefore, even if the magnetic body 21 does not have a large thickness, the electromotive force generated in the thermoelectric conversion element 1a is likely to be large.

[0021] As shown in FIG. 1 , the thermoelectric conversion element 1a includes, for example, a conductive path 25. The conductive path 25 includes a magnetic material 21 and has a meander pattern. This makes it easy to increase the length of the conductive path 25, which increases the electromotive force generated in the thermoelectric conversion element 1a. For example, by connecting wiring to one end 25p and the other end 25q of the conductive path 25, the electromotive force generated in the thermoelectric conversion element 1a can be extracted to the outside. Alternatively, by applying a voltage between the one end 25p and the other end 25q, a heat flow can be generated in the thickness direction of the substrate 10.

[0022] As shown in FIG. 1 , the conductive path 25 includes a plurality of magnetic bodies 21. The magnetic bodies 21 are, for example, spaced apart at a predetermined interval in the X-axis direction and arranged parallel to one another. For example, the magnetic bodies 21 are arranged at equal intervals in the X-axis direction. The conductive path 25 further includes, for example, a plurality of connectors 22. The connectors 22 electrically connect adjacent magnetic bodies 21 in the X-axis direction. The connectors 22 electrically connect, for example, one end of a magnetic body 21 in the Y-axis direction to the other end of another magnetic body 21 adjacent to that magnetic body 21 in the Y-axis direction. With this configuration, the magnetic bodies 21 are electrically connected in series, which tends to increase the electromotive force generated in the thermoelectric conversion element 1a. One end of each of the magnetic bodies 21 in the Y-axis direction is located on the same side of the magnetic body 21 in the Y-axis direction, and the other end of each of the magnetic bodies 21 in the Y-axis direction is located on the opposite side of the one end of the magnetic body 21 in the Y-axis direction.

[0023] As shown in FIG. 1 , the connectors 22 are formed, for example, in the shape of a rectangular parallelepiped elongated in the Y-axis direction. As long as the connectors 22 can electrically connect adjacent magnetic bodies 21, the material of the connectors 22 is not limited to a specific material. The connectors 22 may contain a substance that generates an electromotive force due to the magneto-thermoelectric effect, and may have, for example, ferromagnetic or antiferromagnetic properties. In this case, the connectors 22 are magnetized, for example, in the positive direction of the X-axis. As a result, when a temperature gradient occurs in the thickness direction of the substrate 10 and a heat flow occurs in the positive direction of the Z-axis, an electromotive force is generated in the negative direction of the Y-axis, which is perpendicular to the Z-axis and the X-axis. This makes it easier for the electromotive force generated in the thermoelectric conversion element 1a to be large. The connectors 22 may also contain a non-magnetic material. In this case, the material of the connectors 22 is, for example, a paramagnetic transition element. The non-magnetic material contained in the connectors 22 is, for example, gold, copper, a copper alloy, aluminum, or an aluminum alloy. The connectors 22 may also be a hardened conductive paste.

[0024] As long as the ratio D / D0 in the magnetic material 21 is 0.80 or greater, the substrate 10 is not limited to a specific substrate. The substrate 10 may be flexible, for example. This allows the thermoelectric conversion element 1a to be arranged along a curved surface. The substrate 10 has elasticity that allows elastic deformation of a strip-shaped test specimen made from the substrate 10 when the test specimen is wound around a cylindrical mandrel with a diameter of 10 cm so that both ends of the strip-shaped test specimen face in the same direction. The substrate 10 may also be a non-flexible substrate, such as a glass substrate.

[0025] When the substrate 10 is flexible, the substrate 10 contains at least an organic polymer, for example. This facilitates reducing the manufacturing cost of the thermoelectric conversion element 1 a. Examples of the organic polymer include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), acrylic resin (PMMA), polycarbonate (PC), polyimide (PI), or cycloolefin polymer (COP).

[0026] As long as the ratio D / D0 of the magnetic material 21 is 0.80 or greater, the glass transition temperature Tg of the substrate 10 is not limited to a specific value. The glass transition temperature Tg of the substrate 10 is, for example, 200°C or less. Since relatively low-temperature conditions can be used to form the magnetic material 21 on the substrate 10, a material having a glass transition temperature Tg of 200°C or less can be used as the substrate. As a result, the energy required to manufacture the thermoelectric conversion element 1a can be easily reduced. In addition, by using a material having a glass transition temperature Tg of 200°C or less as the substrate 10, for example, when the magnetic material 21 is formed as a sputtering film, the sputtered material can easily diffuse into the substrate 10. As a result, adhesion between the substrate 10 and the magnetic material 21 is likely to be high.

[0027] The glass transition temperature Tg of the substrate 10 may be 180° C. or less, 150° C. or less, 120° C. or less, or 100° C. or less. The glass transition temperature Tg of the substrate 10 is, for example, 50° C. or more.

[0028] As long as the ratio D / D0 of the magnetic body 21 is 0.80 or more, the squareness ratio M r / Ms is not limited to a specific value. r / M s is the saturation magnetic susceptibility M in the MH curve of the magnetic material 21 s Residual magnetic susceptibility M r The squareness ratio M r / M s The value of is, for example, 0.6 or more. This allows the thermoelectric conversion element 1a to exhibit a high remanent magnetic susceptibility in zero magnetic field, and the thermoelectric conversion element 1a is likely to have a high power output.

[0029] Squareness ratio M of magnetic body 21 r / M s The squareness ratio M of the magnetic body 21 may be 0.62 or more, 0.63 or more, 0.64 or more, 0.65 or more, or 0.66 or more. r / M s may be 0.7 or more, may be 0.8 or more, or may be 0.9 or more.

[0030] As long as the ratio D / D in the magnetic body 21 is 0.80 or more, the remanent magnetic susceptibility M r is not limited to a specific value. r is 500 emu / cm 3 As a result, the thermoelectric conversion element 1a exhibits a high magneto-thermoelectric effect in zero magnetic field, and the power generation output of the thermoelectric conversion element 1a tends to be high.

[0031] The residual magnetic susceptibility M of the magnetic body 21 r is 550 emu / cm 3 or more, and 600 emu / cm 3 or more, 650 emu / cm 3 or more, 700 emu / cm 3 or more, 800 emu / cm 3 The remanent magnetic susceptibility M of the magnetic body 21 may be r is 900 emu / cm 3 or more, 1000 emu / cm 3 or more, 1200 emu / cm 3or more, 1300 emu / cm 3 or more, 1400 emu / cm 3 The remanent magnetic susceptibility M of the magnetic body 21 may be r is, for example, 2000 emu / cm 3 The residual magnetic susceptibility M of the magnetic body 21 is as follows: r is 1900 emu / cm 3 or less, 1800 emu / cm 3 or less, 1700 emu / cm 3 or less, 1600 emu / cm 3 or less, 1500 emu / cm 3 It may be the following:

[0032] As long as the ratio D / D0 in the magnetic material 21 is 0.80 or more, the maximum value of the slope of the MH curve of the magnetic material 21 is not limited to a specific value. The maximum value of the slope of the MH curve of the magnetic material 21 is, for example, 1.5 emu / (cm 3 × Oe) or more. This allows the thermoelectric conversion element 1a to exhibit a high residual magnetic susceptibility in zero magnetic field, and the power generation output of the thermoelectric conversion element 1a tends to be high. The maximum value of the gradient of the M-H curve of the magnetic material 21 is 5 emu / (cm 3 × Oe) or more, and 3 × Oe) or more, and 3 × Oe) or more, and 3 × Oe) or more.

[0033] The magnetic body 21 is, for example, a film. As long as the ratio D / D0 in the magnetic body 21 is 0.80 or more, the magnetic body 21 is not limited to a specific film. The magnetic body 21 is, for example, a sputtered film. This makes it easier for the magnetic body 21 to be formed as a high-density film in the thermoelectric conversion element 1a, more reliably suppressing noise generation and increasing the power generation output of the thermoelectric conversion element 1a. The magnetic body 21 may be a film other than a sputtered film. The magnetic body 21 may be, for example, a vapor deposition film or a plated film. The magnetic body 21 is, for example, a non-sintered body.

[0034] As long as the ratio D / D in the magnetic body 21 is 0.80 or more, the thickness of the substrate 10 is not limited to a specific value. The thickness of the substrate 10 is, for example, 200 μm or less. This tends to reduce the thermal resistance of the thermoelectric conversion element 1 a in the thickness direction of the substrate 10.

[0035] The thickness of the substrate 10 may be 190 μm or less, 180 μm or less, 170 μm or less, or 160 μm or less. The thickness of the substrate 10 may be 150 μm or less, 140 μm or less, 130 μm or less, 120 μm or less, or 110 μm or less. The thickness of the substrate 10 may be 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, or 60 μm or less. The thickness of the substrate 10 is, for example, 10 μm or more. This makes it easy to transport the substrate 10 and allows the substrate 10 to have desired handleability. The thickness of the substrate 10 may be 20 μm or more, or 30 μm or more.

[0036] As long as the ratio D / D0 of the magnetic body 21 is 0.80 or greater, the thickness of the magnetic body 21 is not limited to a specific value. The magnetic body 21 has a thickness of, for example, 1000 nm or less. This reduces the amount of material used to form the magnetic body 21 in the thermoelectric conversion element 1a, making it easier to reduce the manufacturing cost of the thermoelectric conversion element 1a. In addition, breaks in the conductive path 25 in the thermoelectric conversion element 1a are less likely to occur.

[0037] The thickness of the magnetic body 21 may be 750 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, or 200 nm or less. The thickness of the magnetic body 21 is, for example, 10 nm or more. This makes it easier for the thermoelectric conversion element 1a to exhibit high durability. The thickness of the magnetic body 21 may be 20 nm or more, 30 nm or more, or 50 nm or more.

[0038] As long as the ratio D / D0 of the magnetic body 21 is 0.80 or greater, the width of each magnetic body 21, which is the dimension in the X-axis direction, is not limited to a specific value. The width of each magnetic body 21 is, for example, 500 μm or less. This reduces the amount of material used to form the magnetic body 21 in the thermoelectric conversion element 1a, making it easier to reduce the manufacturing cost of the thermoelectric conversion element 1a. In addition, it is easy to arrange a large number of magnetic bodies 21 in the X-axis direction, making it easier to increase the electromotive force generated in the thermoelectric conversion element 1a.

[0039] The width of each magnetic body 21 may be 400 μm or less, 300 μm or less, 200 μm or less, 100 μm or less, or 50 μm or less. The width of each magnetic body 21 is, for example, 0.1 μm or more. This makes it less likely that the conductive path 25 in the thermoelectric conversion element 1a will break, and the thermoelectric conversion element 1a is more likely to exhibit high durability. The width of each magnetic body 21 may be 0.5 μm or more, 1 μm or more, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 50 μm or more.

[0040] As long as the connector 22 can electrically connect adjacent magnetic bodies 21 to each other, the thickness of the connector 22 is not limited to a specific value. The thickness of the connector 22 is, for example, 1000 nm or less. This reduces the amount of material used to form the connector 22, making it easier to reduce the manufacturing cost of the thermoelectric conversion element 1a. In addition, breaks in the conductive path 25 in the thermoelectric conversion element 1a are less likely to occur. The thickness of the connector 22 may be 750 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, or 200 nm or less.

[0041] The thickness of the connector 22 is, for example, 5 nm or more. This makes it easier for the thermoelectric conversion element 1 a to exhibit high durability. The thickness of the connector 22 may be 10 nm or more, 20 nm or more, 30 nm or more, or 50 nm or more.

[0042] As long as the connecting bodies 22 can electrically connect adjacent magnetic bodies 21 to each other, the width, which is the minimum dimension in the X-axis direction, of each connecting body 22 is not limited to a specific value. The width of each connecting body 22 is, for example, 500 μm or less. This reduces the amount of material used to form the connecting bodies 22 in the thermoelectric conversion element 1a, making it easier to reduce the manufacturing cost of the thermoelectric conversion element 1a. In addition, it is easy to arrange a large number of magnetic bodies 21 in the X-axis direction, making it easier to increase the electromotive force generated in the thermoelectric conversion element 1a.

[0043] The width of each connector 22 may be 400 μm or less, 300 μm or less, 200 μm or less, 100 μm or less, or 50 μm or less. The width of each connector 22 is, for example, 0.1 μm or more. This makes it less likely that the conductive path 25 in the thermoelectric conversion element 1a will break, and the thermoelectric conversion element 1a is more likely to exhibit high durability. The width of each connector 22 may be 0.5 μm or more, 1 μm or more, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, or 30 μm or more.

[0044] An example of a manufacturing method of the thermoelectric conversion element 1a will be described. First, a thin film of precursors of the magnetic material 21 is formed on one main surface of the substrate 10 by a method such as sputtering, chemical vapor deposition (CVD), pulsed laser deposition (PLD), ion plating, or plating. Next, a photoresist is applied to the thin film, a photomask is placed on the thin film, and exposure is performed, followed by wet etching. This forms a linear pattern of precursors of multiple magnetic materials 21 arranged at predetermined intervals. Next, a thin film of precursors of the connectors 22 is formed on one main surface of the substrate 10 by a method such as sputtering, CVD, PLD, ion plating, or plating. Next, a photoresist is applied to the thin film of precursors of the connectors 22, a photomask is placed on the thin film of precursors of the connectors 22, and exposure is performed, followed by wet etching. This results in the connectors 22, and the linear patterns of precursors of the magnetic material 21 are electrically connected to each other. Next, the precursors of the magnetic material 21 are magnetized to form the magnetic materials 21. In this way, the thermoelectric conversion element 1a is obtained. If necessary, the precursor of the connector 22 may be magnetized to form the connector 22.

[0045] The ratio D / D in the magnetic body 21 can be adjusted to a desired range by adjusting the conditions for forming the precursor thin film of the magnetic body 21. For example, when forming the precursor thin film of the magnetic body 21 by sputtering, the ratio D / D in the magnetic body 21 can be adjusted to a desired range by adjusting the pressure of the atmosphere around the substrate 10 where sputtering is performed and the distance between the substrate 10 and the target material.

[0046] When forming a thin film of the precursor of the magnetic material 21 by sputtering, the pressure of the atmosphere around the substrate 10 where sputtering is performed is not limited to a specific value as long as the ratio D / D in the magnetic material 21 is 0.80 or greater. The pressure may be, for example, 2.5 Pa or less, or 2.0 Pa or less. The pressure is preferably 0.5 Pa or less. This makes it possible to increase the density of the magnetic material 21 and to make the ratio D / D 0 greater than or equal to 0.80, even when the substrate 10 contains an organic material such as an organic polymer. The pressure of the atmosphere around the substrate 10 where sputtering is performed is more preferably 0.3 Pa or less, even more preferably 0.2 Pa or less, and particularly preferably 0.1 Pa or less. The pressure is preferably 0.05 Pa or greater. This makes it possible to easily generate discharge and stably form a thin film, even when the target is a magnetic material.

[0047] When forming a thin film of the precursor of the magnetic material 21 by sputtering, the TS distance, which is the distance between the target material and the substrate 10, is not limited to a specific value as long as the ratio D / D in the magnetic material 21 is 0.80 or more. The TS distance is, for example, 120 mm or less. In this case, even if the substrate 10 contains an organic material such as an organic polymer, the density of the magnetic material 21 is likely to be high, and the ratio D / D is likely to be 0.80 or more. The TS distance is preferably 100 mm or less, more preferably 80 mm or less, and even more preferably 60 nm or less. The TS distance is, for example, 40 mm or more. In this case, even if the target is a magnetic material, discharge is likely to occur, and a thin film can be stably formed.

[0048] When forming a thin film of the precursor of the magnetic material 21 by sputtering, the magnetic field is not limited to a specific value as long as the ratio D / D in the magnetic material 21 is 0.80 or more. The magnetic field is, for example, 150 mT or less. In this case, even if the substrate 10 contains an organic material such as an organic polymer, the density of the magnetic material 21 is likely to be high, and the ratio D / D is likely to be 0.80 or more. The magnetic field is, for example, 30 mT or more. In this case, even if the target is a magnetic material, discharge is likely to occur, and a thin film can be stably formed.

[0049] The thermoelectric conversion element 1 a may be provided together with, for example, an adhesive layer. In this case, the substrate 10 is disposed between the magnetic material 21 and the adhesive layer in the thickness direction of the substrate 10. This allows the thermoelectric conversion element 1 a to be attached to an article by pressing the adhesive layer against the article.

[0050] The adhesive layer contains, for example, a rubber-based adhesive, an acrylic-based adhesive, a silicone-based adhesive, or a urethane-based adhesive. The thermoelectric conversion element 1a may be provided together with an adhesive layer and a separator. In this case, the separator covers the adhesive layer. The separator is typically a film that can maintain the adhesive force of the adhesive layer while covering the adhesive layer and can be easily peeled off from the adhesive layer. The separator is, for example, a film made of a polyester resin such as PET. By peeling off the separator, the adhesive layer is exposed, allowing the thermoelectric conversion element 1a to be attached to an article.

[0051] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. First, evaluation methods for the examples and comparative examples will be described.

[0052] [Theoretical Density] Using a Rigaku SmartLab X-ray diffractometer, Cu-Kα rays were irradiated onto samples made from the magnetic material of the thermoelectric conversion elements according to each example and comparative example to obtain an XRD pattern of the magnetic material crystal. From the peak position of the obtained XRD pattern, the interplanar spacing d of the magnetic material crystal was determined based on the relationship 2d sinθ = λ. 2θ is the peak position of the XRD pattern, and λ is 0.1541 nm, the wavelength of the Cu-Kα rays. The lattice constant a of the crystal was determined from the interplanar spacing d value. In this determination, the Miller index of the crystal was (001).

[0053] Using a Rigaku Corporation ZSX PrimusIII+ X-ray fluorescence analyzer, the elemental composition of samples prepared from the magnetic material of the thermoelectric conversion element according to each example and each comparative example was measured. This measurement detected Fe and Ga in the samples. From this measurement result, the molar fraction x of Fe in the magnetic material was calculated. Furthermore, the apparent atomic weight M [g / mol] of the magnetic material was determined based on the relationship M = 55.85 [g / mol] x + 69.72 [g / mol] x (1 - x) with reference to the atomic weight of Fe, 55.85 [g / mol], and the atomic weight of Ga, 69.72 [g / mol]. Using the number N of atoms in the unit lattice of the crystal structure identified from the XRD results, the apparent atomic weight M of the magnetic material, and the value of the lattice constant a of the crystal, the theoretical density D of the magnetic material was calculated as D = (N x M) / a 3 The results are shown in Table 2.

[0054] [Measured Density] Using a Rigaku SmartLab X-ray diffractometer, X-ray reflectivity profiles of the magnetic materials were obtained by X-ray reflectometry (XRR) for samples prepared from the magnetic materials of the thermoelectric conversion elements according to each Example and Comparative Example. The measured density D of the magnetic materials was determined by fitting from the obtained X-ray reflectivity profiles. The results are shown in Table 2. Table 2 also shows the ratio D / D of the measured density D to the theoretical density D of the magnetic materials of the thermoelectric conversion elements according to each Example and Comparative Example.

[0055] [Specific Resistivity] Using a non-contact resistance measuring device NC-80LINE manufactured by Napson Corporation, the sheet resistance of the magnetic body of the thermoelectric conversion element according to each example and each comparative example was measured by the eddy current method in accordance with Japanese Industrial Standards (JIS) Z 2316. The thickness of the magnetic body of the thermoelectric conversion element according to each example and each comparative example was determined from the results of the XRR measurement. In each example and comparative example, the specific resistance of the magnetic body was determined from the sheet resistance and thickness of the magnetic body. The results are shown in Table 2.

[0056] [Inter-Terminal Resistance] The electrical resistance between both ends of the meander-patterned conductive path was measured in each of the thermoelectric conversion elements according to the examples and comparative examples. The results are shown in Table 2.

[0057] [Magnetic Properties] The magnetic properties of the magnetic material of the thermoelectric conversion element according to each Example and Comparative Example were measured using a Qantum Design physical property measuring device, PPMS-versalab. Measurement samples were prepared by cutting the thermoelectric conversion element according to each Example and Comparative Example into 2 mm squares. Additionally, a Vibration Sample Magnetrometer (VSM) was used for the measurements, sweeping a magnetic field of ±10,000 Oe at a temperature of 300 K. The saturation magnetic susceptibility Ms and remanent magnetic susceptibility Mr of the magnetic material were determined taking into account the thickness of the magnetic material determined from the XRR measurement results and the area of ​​the magnetic material in the measurement sample. In the M-H curve of the magnetic material, the magnetic moment of the magnetic material at a magnetic flux density of 1 T was determined as the saturation magnetic susceptibility Ms of the magnetic material, and the magnetic moment of the magnetic material at a magnetic flux density of 0 T was determined as the remanent magnetic susceptibility Mr of the magnetic material. Additionally, the ratio Mr / Ms of the remanent magnetic susceptibility Mr to the saturation magnetic susceptibility Ms was determined as the squareness ratio. The results are shown in Table 2.

[0058] [Thermoelectric Properties] The thermoelectric conversion elements according to each Example and Comparative Example were fixed between a pair of Cu plates measuring 30 mm, 30 mm, and 5 mm using silicone grease KS609 manufactured by Shin-Etsu Chemical Co., Ltd. to prepare samples for evaluating thermoelectric properties. The samples were placed on a cooling plate SCP-125 manufactured by AS ONE Corporation. A film heater manufactured by Shinwa Measuring Co., Ltd. was fixed on top of the upper Cu plate using double-sided tape No. 5000NS manufactured by Nitto Denko Corporation. This heater had dimensions of 30 mm square and an electrical resistance of 20 Ω. With the temperature of the cooling plate maintained at 25°C, the film heater was heated under constant voltage control of 10 V, and the heat output from the film heater was 0.52 W / cm. 2 The temperature was adjusted to . At this time, the electromotive force generated in the thermoelectric conversion element was measured using a data logger, and the value of the electromotive force in the steady state was read. In addition, the noise and S / N ratio were calculated from the measurement results of the data logger. The results are shown in Table 2.

[0059] [Adhesion] The adhesion between the thin film formed on the substrate and the substrate was evaluated using the cross-cut method of JIS K 5600-5-6. Eleven cuts, spaced 1 mm apart, were made vertically and horizontally in the thin film using a utility knife, creating a total of 100 grid-like squares. Tape was placed on the thin film so as to cover the 100 squares. The edge of the tape was then grasped and the tape was peeled off in a direction at a 60° angle to the surface of the thin film over a period of 0.5 to 1.0 seconds. The state of peeling of the 100 squares on the thin film was visually confirmed. A rating of "A" was given when all squares remained intact, and a rating of "X" was given when peeling was observed in at least one square. The results are shown in Table 2.

[0060] Example 1: A 96-nm-thick thin film was formed on a 50-μm-thick polyethylene terephthalate (PET) film by DC magnetron sputtering using a target material containing Fe and Ga. Table 1 shows the thin film formation conditions. A magnet with a magnetic flux density of 100 mT was used in the DC magnetron sputtering. The glass transition temperature of the PET film was 78°C. In this target material, the Fe content:Ga content ratio was 3:1. In the DC magnetron sputtering, the distance between the target material and the PET film was adjusted to 75 mm. In addition, argon gas was supplied as the process gas at a pressure of 0.1 Pa in the DC magnetron sputtering. The temperature of the PET film was adjusted to 130°C. A photoresist was applied to the thin film, and a photomask was placed on the thin film to perform exposure, followed by wet etching. This resulted in the formation of 98 FeGa-containing linear patterns arranged at predetermined intervals. The width of each FeGa-containing linear pattern was 100 μm, the length of each FeGa-containing linear pattern was 15 mm, and the total length of the FeGa-containing linear patterns was 147 cm. Then, a Cu thin film having a thickness of 100 nm was formed by DC magnetron sputtering using a Cu-containing target material. A photoresist was applied to the Cu thin film, and a photomask was placed on the Cu thin film to perform exposure, followed by wet etching. This resulted in the formation of a Cu-containing linear pattern having a width of 40 μm. The Cu-containing linear patterns electrically connected adjacent pairs of FeGa-containing linear patterns, forming a meander-patterned conductive path. Using an electromagnet with a central magnetic flux density of 0.5 T, the FeGa-containing linear patterns were magnetized in a direction parallel to the plane of the PET film and perpendicular to the longitudinal direction of the FeGa-containing linear patterns to form a magnetic body. The magnetic body of Example 1 had a resistivity of 1.1×10 -4 The resistance was Ωcm, and the thickness of the magnetic body was 96 nm. In this way, a thermoelectric conversion element according to Example 1 was obtained. This thermoelectric conversion element generated an electromotive force based on the anomalous Nernst effect.

[0061] Example 2 A thermoelectric conversion element according to Example 2 was obtained in the same manner as Example 1, except for the following points. As shown in Table 1, a glass plate was used as the substrate instead of a PET film. Argon gas was supplied as the process gas at a pressure of 0.5 Pa, and the distance between the target material and the substrate was adjusted to 80 mm.

[0062] Example 3 As shown in Table 1, a thermoelectric conversion element according to Example 3 was obtained in the same manner as in Example 2, except that argon gas was supplied as the process gas at a pressure of 2 Pa.

[0063] Example 4 As shown in Table 1, a thermoelectric conversion element according to Example 4 was obtained in the same manner as in Example 1, except that argon gas was supplied as the process gas at a pressure of 0.5 Pa and the distance between the target material and the substrate was adjusted to 40 mm.

[0064] Example 5 As shown in Table 1, a thermoelectric conversion element according to Example 5 was obtained in the same manner as in Example 4, except that the distance between the target material and the substrate was adjusted to 60 mm.

[0065] Example 6 As shown in Table 1, a thermoelectric conversion element according to Example 6 was obtained in the same manner as in Example 4, except that the distance between the target material and the substrate was adjusted to 120 mm.

[0066] Comparative Example 1 A thermoelectric conversion element according to Comparative Example 1 was obtained in the same manner as in Example 2, except that argon gas was supplied at a pressure of 3 Pa as the process gas.

[0067] Comparative Example 2 As shown in Table 1, a thermoelectric conversion element according to Comparative Example 2 was obtained in the same manner as in Example 4, except that the distance between the target material and the substrate was adjusted to 180 mm.

[0068] <Comparative Example 3> As shown in Table 1, a thermoelectric conversion element according to Comparative Example 3 was obtained in the same manner as in Example 1, except that argon gas was supplied as the process gas at a pressure of 1 Pa and the distance between the target material and the substrate was adjusted to 80 mm.

[0069] As shown in Table 2, although the specific resistance of the thermoelectric conversion elements according to each Example was lower than that of the thermoelectric conversion elements according to Comparative Examples 1 to 3, the thermoelectric conversion elements according to each Example had a higher electromotive force in a steady state and better thermoelectric conversion characteristics than the thermoelectric conversion elements according to Comparative Examples 1 to 3. Furthermore, the thermoelectric conversion elements according to each Example had lower noise and a higher S / N ratio than the thermoelectric conversion elements according to Comparative Examples 1 to 3. On the other hand, the thermoelectric conversion elements according to Comparative Examples 1 to 3 had a lower electromotive force in a steady state and could not be said to have good thermoelectric conversion characteristics. Furthermore, the thermoelectric conversion elements according to Comparative Examples 1 to 3 had higher noise and a lower S / N ratio.

[0070] As shown in Table 2, the ratio D / D0 of the magnetic material in the thermoelectric conversion element according to each example was 0.80 or more. On the other hand, the ratio D / D0 of the magnetic material in the thermoelectric conversion elements according to Comparative Examples 1 to 3 was less than 0.80. This suggests that a magnetic material with a ratio D / D0 of 0.80 or more is advantageous in terms of improving the thermoelectric conversion characteristics of the thermoelectric conversion element.

[0071] As shown in Table 2, the saturation magnetic susceptibility Ms, remanent magnetic susceptibility Mr, and squareness ratio Mr / Ms of the magnetic material in the thermoelectric conversion element according to each example were higher than those of the magnetic material in the thermoelectric conversion element according to Comparative Example 1. It was suggested that the magnetic properties of the thermoelectric conversion element are likely to be improved by having a ratio D / D of 0.80 or more in the magnetic material.

[0072] As shown in Table 2, the adhesion was evaluated as "A" in Examples 1, 3, and 4 and Comparative Examples 2 and 3, whereas the adhesion was evaluated as "X" in Examples 2 and 3 and Comparative Example 1. This suggests that when the substrate is PET, the adhesion between the thin film formed on the substrate and the substrate is more likely to be high than when the substrate is glass.

[0073] A first aspect of the present invention provides a thermoelectric conversion element comprising: a substrate; and a magnetic body having ferromagnetic or antiferromagnetic properties, the magnetic body being disposed on the substrate; wherein a ratio of an actually measured density of the magnetic body to a theoretical density of the magnetic body is 0.80 or more.

[0074] A second aspect of the present invention provides the thermoelectric conversion element according to the first aspect, wherein the substrate is flexible.

[0075] A third aspect of the present invention provides the thermoelectric conversion element according to the second aspect, wherein the substrate contains at least an organic polymer.

[0076] A fourth aspect of the present invention provides the thermoelectric conversion element according to any one of the first to third aspects, wherein the substrate has a glass transition temperature of 200° C. or less.

[0077] A fifth aspect of the present invention provides a thermoelectric conversion element according to any one of the first to fourth aspects, wherein a squareness ratio, which is a ratio of remanent magnetic susceptibility to saturation magnetic susceptibility in an M-H curve of the magnetic material, is 0.6 or more.

[0078] A sixth aspect of the present invention is the thermoelectric conversion element according to any one of the first to fifth aspects, wherein the remanence of the magnetic body is 500 emu / cm 3 The thermoelectric conversion element described above is provided.

[0079] A seventh aspect of the present invention is the thermoelectric conversion element according to any one of the first to sixth aspects, wherein the maximum value of the slope of the MH curve of the magnetic material is 1.5 emu / (cm 3 × Oe) or more.

[0080] An eighth aspect of the present invention provides the thermoelectric conversion element according to any one of the first to seventh aspects, wherein the magnetic body is a sputtered film.

[0081] A ninth aspect of the present invention provides a thermoelectric conversion element according to any one of the first to eighth aspects, wherein when a temperature gradient occurs in the thickness direction of the base material, an electromotive force is generated in a direction perpendicular to the thickness direction of the base material.

[0082] A tenth aspect of the present invention provides the thermoelectric conversion element according to any one of the first to ninth aspects, wherein the magnetic body generates an electromotive force by the anomalous Nernst effect.

[0083] An eleventh aspect of the present invention provides a thermoelectric conversion element according to any one of the first to tenth aspects, comprising a conductive path including the magnetic material and forming a meander pattern.

[0084]

[0085]

Claims

1. A thermoelectric conversion element comprising a base material and a magnetic material disposed on the base material and having ferromagnetic or antiferromagnetic properties, wherein a ratio of a measured density of the magnetic material to a theoretical density of the magnetic material is 0.80 or more.

2. The thermoelectric conversion element according to claim 1, wherein the base material has flexibility.

3. The thermoelectric conversion element according to claim 2, wherein the base material contains at least an organic polymer.

4. The thermoelectric conversion element according to claim 1, wherein the base material has a glass transition temperature of 200°C or lower.

5. The thermoelectric conversion element according to claim 1, wherein a squareness ratio, which is a ratio of a residual magnetization to a saturation magnetization in an M-H curve of the magnetic material, is 0.6 or more.

6. The residual magnetic susceptibility of the magnetic material is 500 emu / cm 3 or more. The thermoelectric conversion element according to claim 1.

7. The maximum value of the slope of the M-H curve of the magnetic material is 1.5 emu / (cm 3 × Oe) or more. The thermoelectric conversion element according to claim 1.

8. The thermoelectric conversion element according to claim 1, wherein the magnetic material is a sputtering film.

9. The thermoelectric conversion element according to claim 1, wherein the magnetic material generates an electromotive force in a direction orthogonal to a thickness direction of the base material when a temperature gradient occurs in the thickness direction of the base material.

10. The thermoelectric conversion element according to claim 1, wherein the magnetic material generates an electromotive force due to an anomalous Nernst effect.

11. The thermoelectric conversion element according to claim 1, comprising a conductive path including the magnetic material and forming a meander pattern.