Thermoelectric body, thermoelectric power generation element, multi-layer thermoelectric body, multi-layer thermoelectric power generation element, thermoelectric generator, and heat flow sensor

Abstract

[Problem] To provide a thermoelectric body which is not limited to a single crystalline bulk material or an epitaxially grown thin-film, and that can be formed as a film on any substrate and exhibits high coercive force and remnant magnetization with respect to in-plane magnetization. [Solution] A thermoelectric body is provided which is a magnetic film for use in a thermoelectric generation element utilizing the anomalous Nernst effect, characterized by having a magnetization easy axis in the in-plane direction and comprising an amorphous structure.　Preferably, the thermoelectric body is characterized by comprising SmpCo100-p(0<p≤50) or Smp(FeqCo100-q)100-p(0<p≤50, 0≤q≤100).

Description

[Technical field]

[0001] The present invention relates to a thermoelectric material and a multi-layer thermoelectric material that are magnetic materials and are used in a thermoelectric generating element that utilizes the anomalous Nernst effect. [Background technology]

[0002] The anomalous Nernst effect, which appears in ferromagnetic materials, is a phenomenon in which an electric field occurs perpendicular to the heat flow and magnetization. The Seebeck effect, which has been traditionally studied as a thermoelectric power generation technology, is a phenomenon in which the heat flow and electric field appear in the same direction, so when converting thermal energy from a heat source into electrical energy, it is necessary to create a complex structure in which p-type and n-type semiconductors are alternately connected in series and arranged in a matrix.

[0003] On the other hand, if the anomalous Nernst effect is used for thermoelectric power generation, an electric field is generated in the in-plane direction for the heat flow flowing out of the plane, so thermoelectric conversion is possible with an extremely simple structure in which a magnetic wire is extended in the in-plane direction of the heat source. Therefore, thermoelectric power generation using the anomalous Nernst effect has the advantages of being easily applicable to heat sources that are not flat, such as cylindrical, and of enabling low-cost elements.

[0004] As a technique related to such a thermoelectric generating element, technical development of a heat flow sensor using the anomalous Nernst effect is described in Non-Patent Document 1. In addition, some of the present inventors have proposed new thermoelectric conversion materials in Patent Documents 1 to 3. Non-Patent Document 2 describes in detail the crystal structure and magnetic properties of SmCo alloys as rare earth magnets with various composition ratios. However, it does not mention the anomalous Nernst effect. Non-Patent Documents 3 and 4, written by some of the present inventors, report research on the anomalous Nernst effect in SmCo5-based magnets, but do not include any reports on amorphous magnets. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-103535 A [Patent Document 2] JP 2018-190780 A [Patent Document 3] Patent Publication No. 2021-040066 [Non-patent literature]

[0006] [Non-Patent Document 1] Hiroya Sakuraba, "Progress and Prospects of Research on Heat Flow Sensors Using the Anomalous Nernst Effect," Metals, Vol. 91, No. 7, pp. 573-580 (2021) [Non-Patent Document 2] Ken Ohashi, "Current Status and Future Prospects of Sm2Co17-Based Magnets," Journal of the Japan Institute of Metals, Vol. 76, No. 1, pp. 96-106 (2012) [Non-Patent Document 3] A. Miura, et al.: "Observation of anomalous Ettingshausen effect and large transverse thermoelectric conductivity in permanent magnets": Applied Physics Letters 115, 222403 (2019). [Non-Patent Document 4] A. Miura, et al.: "High-temperature dependence of anomalous Ettingshausen effect in SmCo5-type permanent magnets": Applied Physics Letters 117, 082408 (2020). Summary of the Invention [Problem to be solved by the invention]

[0007] However, in conventional thermoelectric conversion materials using the anomalous Nernst effect, a high anomalous Nernst coefficient has only been obtained in single-crystalline bulk materials, epitaxially grown thin films, and crystalline materials that require high-temperature heat treatment. Therefore, there is a problem of inferior versatility. In addition, in conventional thermoelectric conversion materials using the anomalous Nernst effect, except for bulk permanent magnets, there is a problem that an external magnetic field needs to be applied for the operation of the anomalous Nernst effect because the coercive force and the ratio of the residual magnetization to the saturation magnetization are small.

[0008] Therefore, in order to realize thermoelectric applications using the anomalous Nernst effect, a thin film that can be formed on any substrate, not limited to single-crystalline bulk materials or epitaxially grown thin films, and has a high anomalous Nernst coefficient, high coercive force, and a high ratio of residual magnetization to saturation magnetization is required. Therefore, an object of the thermoelectric body of the present invention is to provide a thermoelectric body that can be formed on any substrate and can exhibit a high coercive force with respect to in-plane magnetization and a high ratio of residual magnetization to saturation magnetization. In addition, the multilayer thermoelectric body of the present invention uses a laminated structure of a rare-earth-based metallic amorphous magnetic alloy material having an in-plane easy magnetization direction with a large coercive force and residual magnetization and another ferromagnetic material having a giant anomalous Nernst effect, so that a large anomalous Nernst effect can be achieved without applying an external magnetic field to a conventional ferromagnetic material. An object of the present invention is to provide a multilayer thermoelectric body capable of realizing voltage generation.

Means for Solving the Problems

[0009] 〔1〕The thermoelectric body of the present invention is a thermoelectric body that is a magnetic thin film used in a thermoelectric power generation element utilizing the anomalous Nernst effect, characterized by having an easy axis of magnetization in the in-plane direction and an amorphous structure. 〔2〕In the thermoelectric body 〔1〕 of the present invention, preferably, Sm p Co 100-p (0 < p ≦ 50) is included. 〔3〕In the thermoelectric body [2] of the present invention, preferably, 15 ≤ p ≤ 35, and more preferably 20 ≤ p ≤ 30. 〔4〕In the thermoelectric body [1] of the present invention, preferably, Sm p (Fe q Co 100-q ) 100-p (0 < p ≤ 50, 0 ≤ q ≤ 100) is included. 〔5〕In the thermoelectric body [4] of the present invention, preferably, 15 ≤ p ≤ 35, 5 ≤ q ≤ 45, and more preferably 20 ≤ p ≤ 30, 10 ≤ q ≤ 35. 〔6〕The thermoelectric power generation element of the present invention preferably has the thermoelectric bodies [1] to [5] of the present invention and a substrate that supports the thermoelectric body.

[0010] 〔7〕The multilayer thermoelectric body of the present invention has a laminated structure of a first magnetic material layer made of a rare earth-based intermetallic amorphous magnetic alloy, which has an easy magnetization axis showing a large coercive force and a large residual magnetization ratio with respect to the saturation magnetization in the in-plane direction and shows a large anomalous Nernst effect, and a second magnetic material layer made of a magnetic material different from the rare earth-based intermetallic amorphous magnetic alloy material and showing a huge anomalous Nernst effect. 〔8〕In the multilayer thermoelectric body [7] of the present invention, preferably, the large coercive force means a case where the coercive force is 10 mT or more, the large residual magnetization ratio with respect to the saturation magnetization means 0.3 or more, the large anomalous Nernst effect means a thermoelectric power of 1 μV / K or more, and the huge anomalous Nernst effect means a thermoelectric power of 5 μV / K or more. 〔9〕The multilayer thermoelectric power generation element of the present invention preferably has the multilayer thermoelectric body [7] or [8] of the present invention and a substrate that supports the thermoelectric body. 〔10〕It is preferably a bendable thermoelectric generator using the thermoelectric power generation elements [1] to [6] of the present invention or the multilayer thermoelectric power generation elements [7] to [9]. 〔11〕It is preferably a bendable heat flux sensor using the thermoelectric power generation elements [1] to [6] of the present invention or the multilayer thermoelectric power generation elements [7] to [9].

Advantages of the Invention

[0011] The thermoelectric generating element of the present invention is useful for applying the lateral thermoelectric effect to real life by applying the rare earth intermetallic amorphous magnetic alloy to lateral thermoelectric conversion that operates without an external magnetic field. The multilayer thermoelectric generation element of the present invention uses a layered structure of a rare earth intermetallic amorphous magnetic alloy material that exhibits an in-plane easy magnetization direction with large coercive force and remanent magnetization and a large anomalous Nernst effect, and another ferromagnetic material that has a giant anomalous Nernst effect, making it possible to realize a large anomalous Nernst effect without applying an external magnetic field to conventional ferromagnetic materials. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing a typical anomalous Nernst thermopile structure for thermoelectric conversion that generates electromotive force in a direction transverse to the heat flow direction, illustrating one embodiment of the present invention. [Figure 2A] This shows an example of film formation for examining the optimal composition ratio of a rare earth-based intermetallic amorphous magnetic alloy according to one embodiment of the present invention, and is a schematic plan view of the structure of an amorphous SmpCo100-p (0≦p≦100) composition gradient film. [Figure 2B] This shows an example of film formation for examining the optimal composition ratio of a rare earth-based intermetallic amorphous magnetic alloy according to one embodiment of the present invention, and is a cross-sectional view showing a schematic structure of an amorphous SmpCo100-p (0≦p≦100) composition gradient film. [Figure 2C] FIG. 1 shows XRD patterns of amorphous SmpCo100-p (0≦p≦100) compositionally graded films at different p values. [Figure 2D] The cross-sectional bright-field (BF)-STEM image and microbeam electron diffraction pattern are shown for the region with a high Sm composition ratio on the right side shown in (A) in Figure 2A. [Figure 2E] The cross-sectional bright-field (BF)-STEM image and the microbeam electron diffraction pattern are shown for the region in (B) in FIG. 2A, approximately in the center, where the composition ratios of Co and Sm are approximately equal. [Figure 2F]The cross-sectional bright-field (BF)-STEM image and microbeam electron diffraction pattern of the region with a high Co composition ratio on the left side shown in (C) in Figure 2A are shown. [Diagram 3] 1 is a graph showing the composition dependence of the temperature change per unit current density due to the anomalous Ettingshausen effect (the reciprocal phenomenon of the anomalous Nernst effect) in an amorphous SmpCo100-p (0≦p≦100) compositionally graded film on an MgO substrate. [Figure 4] (a) is a schematic cross-sectional view showing the layered structure for producing an amorphous Sm20Co80 film. (b) shows the magnetic field dependence curve (black symbols) of the in-plane magnetization of the evaporated amorphous Sm20Co80 film. (c) shows the external magnetic field dependence of the ANE electric field when the heater output is changed. (d) shows the temperature gradient dependence of the ANE electric field. [Diagram 5] (a) is a diagram showing the schematic structure of a thermopile for detecting heat flux using an amorphous Sm20Co80 thin film. (b) is a diagram showing a schematic experimental setup for heat flux sensing. (c) is a diagram showing the observation results of the ANE voltage signal by the above experimental setup for an amorphous Sm20Co80 film evaporated on a polyethylene naphthalate (PEN) substrate, where the horizontal axis indicates the magnetic field strength H. (d) is the same as (c), where the horizontal axis indicates the heat flow density JQ in the direction penetrating the sample surface. [Figure 6] (a) is a cross-sectional view showing the structure of an amorphous Sm20(FeqCo100-q)80 (0≦q≦100) compositionally graded film. (b) is a diagram showing XRD patterns at different q values ​​in Fig. 6(a). (c) shows cross-sectional bright-field (BF)-STEM images and microbeam electron diffraction patterns to confirm the results obtained by XRD. [Figure 7] This shows the composition dependence of the temperature change per unit current density due to the anomalous Ettingshausen effect in an amorphous Sm20(FeqCo100-q)80 (0≦q≦100) compositionally graded film on an MgO substrate. [Figure 8](a) shows a schematic diagram of the amorphous Sm20(Fe23Co77)80 film manufacturing process, (b) shows the magnetic field dependence curve of the in-plane magnetization of the evaporated Sm20(Fe23Co77)80 film, (c) shows the external magnetic field dependence of the ANE electric field when the heater power is changed, and (d) shows the temperature gradient dependence of the ANE electric field. [Figure 9] 1 shows an outline of a multi-layer thermopile structure of the present invention, which uses a rare earth intermetallic amorphous magnetic alloy and a different magnetic material having a large anomalous Nernst effect. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The technical terms used in this specification are defined as follows: "Thermoelectric materials" are substances that can convert heat into electricity. They are used, for example, in power generation modules and temperature control elements, and are useful for providing environmentally friendly energy and further increasing the efficiency of energy conservation. The "Nernst effect" is a phenomenon reported by E. Nernst et al. in 1886. When an external magnetic field H is applied to a conductive material to which a temperature gradient ∇T is applied, an electric field is generated in the cross product direction of H and ∇T (see Non-Patent Document 1). The "anomalous Nernst effect" is a phenomenon unique to magnetic materials, which generates an electric field in the direction of the cross product of the magnetization M of the magnetic material and the temperature gradient ∇T, rather than an external magnetic field (see Non-Patent Document 1). Hereinafter, the anomalous Nernst effect may be abbreviated to ANE (anomalous Nernst effect). A "thermopile" is a structure in which multiple thermoelectric conversion materials are connected in series or in parallel and is used to boost thermoelectromotive force.

[0014] First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 illustrates an embodiment of the present invention, showing a typical Nernst thermopile structure for lateral thermoelectric conversion in which the input heat flow and the output current are perpendicular to each other. (a) shows a case in which the direction of magnetization M is uniform with respect to the substrate, and (b) shows a case in which the direction of magnetization M alternates between right and left between adjacent thermoelectric bodies. The thermoelectric material of the present invention is a magnetic film used in a thermoelectric generating element utilizing the anomalous Nernst effect. The thermoelectric material 11 of the present invention is characterized by having an easy axis of magnetization in the in-plane direction and an amorphous structure. By using this, a horizontal thermoelectric conversion element capable of generating an electromotive force in the in-plane direction without an external magnetic field can be obtained.

[0015] [Thermoelectric power generation element 10] Fig. 1(a) is a diagram illustrating a thermoelectric generating element 10 using the thermoelectric conversion material of the present invention. The thermoelectric generating element 10 shown in Fig. 1(a) has a substrate 13, a thermoelectric body 11 and a connector 12 arranged (supported) on this substrate 13, and a connection terminal 14. In Fig. 1(a), the material of the thermoelectric body 11 is represented as Material A, and the material of the connector 12 is represented as Material B. The thermoelectric element 11 is typically made of amorphous Sm 20 Co 80 The thermoelectric element 11 is made of a rare earth intermetallic amorphous magnetic alloy film (magnetic film) such as a thin film. The rare earth intermetallic amorphous magnetic alloy film has strong in-plane magnetic anisotropy and an easy axis of magnetization in the in-plane direction. For this reason, the rare earth intermetallic amorphous magnetic alloy film exhibits a large coercive force and a large residual magnetization relative to saturation magnetization, and the magnetization is maintained even when the magnetic field is returned to zero after an external magnetic field is applied. The magnetization direction of the rare earth intermetallic amorphous magnetic alloy is oriented in the direction of the applied external magnetic field and can be controlled to any direction, making it suitable for controlling the output of the anomalous Nernst effect. The rare earth intermetallic amorphous magnetic alloy used as the material (Material A) constituting the thermoelectric element 11 is Sm p Co 100-p (0 <p≦50)や、Sm p (Fe q Co 100-q ) 100-pIt is preferably included that (0 < p ≤ 50, 0 ≤ q ≤ 100), Sm p Co 100-p (15 ≤ p ≤ 35), or Sm p (Fe q Co 100-q ) 100-p It is more preferably included that (15 ≤ p ≤ 50, 5 ≤ q ≤ 45), Sm p Co 100-p (20 ≤ p ≤ 30), or Sm p (Fe q Co 100-q ) 100-p It is even more preferably included that (20 ≤ p ≤ 30, 10 ≤ q ≤ 35). Further, the thermoelectric body 11 may be a uniform alloy film, but for example, it may be a multi-layer structure in which different single metal layers are alternately laminated on a nanoscale, etc., and is not limited thereto. In addition, the thickness of the magnetic body film can be, for example, about 10 nm to 1 μm, but is not particularly limited thereto. The connector 12 is composed of a non-magnetic body (for example, copper (Cu), chromium (Cr), gold (Au), silver (Ag), platinum (Pt)) that does not exhibit an anomalous Nernst effect as Material B. Alternatively, the connector 12 may be composed of a ferromagnetic body (for example, Fe, NdFeB, MnGa) having an anomalous Nernst coefficient of the opposite sign to that of the thermoelectric body 11, or a ferromagnetic body Sm n Fe 1-n (0 ≤ n ≤ 100). The substrate 13 is composed of MgO, Si - SiO2, Al2O3, AlN, glass, diamond, polyethylene naphthalate (PEN), polyimide film (Kapton (registered trademark of DuPont)), polymer, etc. The connection terminal 14 is made of the same material (Material B) as the connector 12 here and is provided at both ends of the thermoelectric body 11. Note that the connection terminal 14 may be made of the same material (Material A) as the thermoelectric body 11, and the arrangement of the thermoelectric body 11 and the connector 12 in FIG. 1 may be interchanged.

[0016] The thermoelectric element 11 is an amorphous Sm 20 Co 80 The thermoelectric element 11 is formed by forming a rare earth intermetallic amorphous magnetic alloy film, such as a thin film, into a thin wire, and is magnetized in the direction M shown in FIG. 1(a). Due to the anomalous Nernst effect, the thermoelectric element 11 is magnetized in a direction perpendicular to the magnetization direction M (the direction of heat flow J shown in FIG. 1(a)). Q 1(a) (the longitudinal direction of thermoelectric body 11 and connector 12).

[0017] The connectors 12 are arranged on the surface of the substrate 13 in parallel to each of the thermoelectric bodies 11, 11, .... One connector 12 is arranged between a pair of adjacent thermoelectric bodies 11, 11, and the connector 12 electrically connects one end side of one thermoelectric body 11 to the other end side of the other thermoelectric body 11. As a result, the thermoelectric bodies 11 are electrically connected in series by the connectors 12.

[0018] As described above, the thermoelectric generating element 10 is made of amorphous Sm 20 Co 80 The thermoelectric element 11 is made of a rare earth intermetallic amorphous magnetic alloy film such as a thin film. 20 Co 80 According to the thermoelectric body 11 constituted by a rare earth intermetallic amorphous magnetic alloy film such as a thin film, it is possible to increase the effective length in the electric field direction and increase the thermoelectromotive force. Therefore, according to the present embodiment, by using such a thermoelectric body 11, it is possible to provide a thermoelectric generating element 10 in a form that is easy to put into practical use.

[0019] [Thermoelectric power generation element 20] Fig. 1(b) is a diagram illustrating a thermoelectric generating element 20 using the thermoelectric conversion material of the present invention. The thermoelectric generating element 20 shown in Fig. 1(b) has a substrate 23, a thermoelectric body 21 and a reverse magnetized connector 22 arranged (supported) on the substrate 23, and a connection terminal 24. In Fig. 1(b), the materials of the thermoelectric body 21 and the reverse magnetized connector 22 are both represented as Material A, and the material of the connection terminal 24 is represented as Material B. The thermoelectric element 21 and the reverse magnetization connector 22 are made of amorphous Sm, similar to the thermoelectric element 11. 20 Co 80 It is composed of a rare earth intermetallic amorphous magnetic alloy film, such as a thin film. Even if the thermoelectric elements 21 and the opposite magnetized connectors 22 are made of the same material, by arranging the thermoelectric elements 21 and the opposite magnetized connectors 22 having opposite magnetization directions M alternately, the ANE electric fields are not cancelled out and the voltage is increased. The substrate 23, like the above-mentioned substrate 13, is made of silicon, magnesium oxide, or the like. The connection terminals 24 may be made of the same material (Material B) as the connector 12, and may be made of a non-magnetic material that does not exhibit the anomalous Nernst effect, such as copper (Cu), chromium (Cr), gold (Au), silver (Ag), or platinum (Pt). The connection terminals 24 are provided on both ends of the thermoelectric body 21. The connection terminals 24 may be made of the same material (Material A) as the thermoelectric body 21 and the reverse magnetization connector 22.

[0020] The opposite magnetized connectors 22 are arranged on the surface of the substrate 23 in parallel to each of the thermoelectric bodies 21, 21, .... One opposite magnetized connector 22 is arranged between a pair of adjacent thermoelectric bodies 21, 21, and the opposite magnetized connector 22 electrically connects one end side of one thermoelectric body 1 to the other end side of the other thermoelectric body 1. As a result, the thermoelectric bodies 21 are electrically connected in series by the opposite magnetized connectors 22.

[0021] As described above, the thermoelectric generating element 20 is made of amorphous Sm 20 Co 80The magnet includes a thermoelectric element 21 and a reverse magnetization connector 22, which are made of a rare earth intermetallic amorphous magnetic alloy film such as a thin film. 20 Co 80 The thermoelectric element 21 and the reverse magnetized connectors 22 made of thin films can increase the effective length in the electric field direction and increase the thermoelectromotive force. Therefore, according to this embodiment, by using such a thermoelectric element 21 and the reverse magnetized connectors 22, it is possible to provide a thermoelectric generating element 20 that is easily put into practical use.

[0022] The magnetic film made of a material such as a rare earth intermetallic amorphous magnetic alloy used for the thermoelectric bodies 11 and 21, the connector 12, and the reverse magnetization connector 22 has a strong axis of easy magnetization in the in-plane direction, and shows a high coercive force and a remanent magnetization ratio to saturation magnetization even in a thick film or thin wire shape, so that it shows a large voltage due to the anomalous Nernst effect even in zero magnetic field, and the magnetization direction of each wire (thermoelectric bodies 11 and 21, the connector 12, and the reverse magnetization connector 22) can be controlled individually, and a thermopile element can be constructed from a single material. Since it is possible to make the film thicker and the wire thinner while maintaining a large remanent magnetization ratio to saturation magnetization, it is possible to increase the thermoelectric output per unit area by narrowing the wire width while suppressing the increase in the internal electrical resistance of the entire thermopile structure by making the film thicker. The magnetization of each layer can also be controlled by using a local magnetic field or the exchange bias effect by adding a pinning layer such as Cr. Here, the rare earth intermetallic amorphous magnetic alloy is Sm p Co 100-p In order to examine the optimal composition ratio of Sm p Co 100-p The film containing the amorphous composition gradient material with p changed from 0 to 100 (hereinafter, simply referred to as "amorphous Sm p Co 100-p We fabricated a compositionally graded film (0≦p≦100) and evaluated its physical properties (structure and thermoelectric performance).

[0023] (amorphous Sm p Co 100-p (0≦p≦100) Compositionally graded film and its structural evaluation) Figure 2A shows amorphous Sm p Co 100-p (0≦p≦100) The structure of the compositionally graded film is shown in a plan view. Fig. 2B shows its cross-sectional view. On an MgO substrate, 100 layers of a compositionally graded material of Sm and Co are stacked, with the total thickness of Sm and Co per layer being 1 nm, and an aluminum thin film for oxidation prevention is vapor-deposited on the top layer. The 1-nm-thick stack is a compositionally graded layer in which the composition ratio of Sm increases from 0 at% to 100 at% along the x-axis in Figs. 2A and 2B. The right side shown in Fig. 2A (A) is the region with a high composition ratio of Sm, the approximate center shown in Fig. 2A (B) is the region with approximately equal composition ratios of Co and Sm, and the left side shown in Fig. 2A (C) is the region with a high composition ratio of Co.

[0024] FIG. 2C shows amorphous Sm p Co 100-p (0≦p≦100) XRD patterns of the compositionally graded films with different p values ​​are shown. The XRD patterns confirmed that most of the Sm-Co binary alloy phase was amorphous, except for the pure Sm and Co-rich regions.

[0025] Figure 2D shows a cross-sectional bright-field (BF)-STEM image and microbeam electron diffraction pattern of the Sm-rich region on the right side of Figure 2A (A). The TEM image supports the results obtained by XRD. In the Sm-rich region, a diffraction pattern showing a crystalline structure is obtained. Figure 2E shows a cross-sectional bright-field (BF)-STEM image and microbeam electron diffraction pattern of the region with roughly equal composition ratios of Co and Sm, roughly near the center of Figure 2A (B). It was confirmed that most of the Sm-Co binary alloy phase was an amorphous phase. Figure 2F shows a cross-sectional bright-field (BF)-STEM image and microbeam electron diffraction pattern of the region with a high Co composition ratio on the left side shown as (C) in Figure 2A. In the Co-rich region, a diffraction image showing a crystalline structure was obtained.

[0026] (amorphous Sm pCo 100-p (0 ≦ p ≦ 100) Composition Gradient Film and Its Thermoelectric Effect) Figure 3 shows an amorphous Sm on an MgO substrate p Co 100-p (0 ≦ p ≦ 100) is a diagram showing the composition dependence of the temperature change per unit charge current density due to the anomalous Ettingshausen effect in the composition gradient film. In the region of 0 at% < Sm ≦ 40 at%, when a current is passed, a heat flow is generated in a direction perpendicular to both the current and the magnetization, and a temperature change is observed. In particular, a large temperature change is observed in the region of Sm = 15 - 35 at%, and the temperature change is maximum at 20 - 30 at%. As an alloy composition range suitable for thermoelectric applications, it is sufficient that 0 < p ≦ 50 shows at least a large anomalous Nernst effect. However, from the above results, due to the inverse relationship between the anomalous Ettingshausen effect and the anomalous Nernst effect, a range of 0 < p ≦ 40 where a sufficiently large anomalous Nernst effect exists is preferred, a range of 15 ≦ p ≦ 35 is more preferred, and a range of 20 ≦ p ≦ 30 is even more preferred. Next, as an amorphous Sm p Co 100-p (0 < p ≦ 50) film, a thermoelectric body composed of an amorphous Sm 20 Co 80 film was fabricated and its thermoelectric performance was evaluated.

[0027] (Thermoelectric Performance Evaluation of Amorphous Sm 20 Co 80 Film) Figure 4(a) is a schematic cross-sectional view showing the laminated state of an amorphous Sm 20 Co 80 film. On an MgO substrate, 100 layers of a laminate with a total thickness of 1 nm of Sm layer and Co layer per layer are laminated, and aluminum is deposited as a cap layer on the uppermost layer. Figure 4(b) is a diagram showing the magnetic field dependence curve (black-filled data points) of the in-plane magnetization of the deposited amorphous Sm 20 Co 80 film. From Figure 4(b), for the amorphous Sm 20 Co 80It can be seen that the film exhibits a large coercive force and a large residual magnetization ratio with respect to saturation magnetization when a magnetic field is applied in the plane. Also shown is the magnetic field dependence curve of in-plane magnetization (white data points) after heating the same film at 100 °C for 1 hour at atmospheric pressure. The almost overlapping magnetization processes confirm the stability of these alloys. Figure 4(c) is a diagram showing the external magnetic field dependence of the ANE electric field when the heater output is changed. When a heat flow is applied in the direction perpendicular to the surface and magnetization is performed in the in-plane direction as in the actual usage form, it is difficult to quantify because a temperature gradient is created in the film thickness direction. In Figures 4(c) and (d), in order to quantitatively measure the temperature gradient, an amorphous Sm 20 Co 80 film was magnetized to create a temperature gradient in the in-plane direction. Quantification of the in-plane temperature gradient is easy, and since it is amorphous, Sm 20 Co 80 Since the electron transport characteristics of the film show isotropic characteristics, the anomalous Nernst coefficient can be estimated in this configuration. From Figure 4(c), the ANE electric field shows an odd dependence on the magnetic field, and amorphous Sm 20 Co 80 It can be seen that when the magnetization of the film saturates, the electric field also saturates. Also, when the heater output is increased, the electric field increases (in Figure 4(c), the thinnest line shows the result when the heater output is high, and the darkest line shows the result when the heater output is low). These behaviors are consistent with ANE. However, since a magnetic field is applied in the direction perpendicular to the film surface, the coercive force and residual magnetization do not appear. Figure 4(d) is a diagram showing the temperature gradient dependence of the ANE electric field. Amorphous Sm 20 Co 80 The film shows an anomalous Nernst coefficient of 1.07 μV / K with the Sm 20 Co 80 composition. Thus, in the thermoelectric material composed of the amorphous Sm p Co 100-p (0 < p ≤ 50) film, thermoelectric power can be obtained due to a relatively high anomalous Nernst effect. Next, the above-prepared amorphous Sm 20 Co 80The thermoelectric performance was evaluated when the thermoelectric material made of the film was used in a thermopile (thermoelectric generating element 10) for detecting heat flux.

[0028] (Thermoelectric performance evaluation of thermopiles for heat flux detection) Figure 5(a) shows amorphous Sm 20 Co 80 FIG. 2 is a schematic diagram showing the structure of a thin-film thermopile for detecting heat flux, similar to that shown in FIG. 1(a).

[0029] Figure 5(b) shows a schematic experimental setup for heat flux sensing. An amorphous Sm 20 Co 80 The thin film and the heat flow sensor are laminated. Figure 5(c) shows the amorphous Sm deposited on the PEN substrate. 20 Co 80 The figure shows the results of the ANE voltage signal observed with the above experimental configuration of the film. The horizontal axis indicates the strength of the magnetic field H applied in the in-plane direction. As shown in Fig. 5(c), a signal showing an odd dependence on the magnetic field, which is characteristic of the ANE electric field, was obtained. Since the magnetic field was applied in the in-plane direction, it is clear that the amorphous Sm 20 Co 80 The results obtained reflect the large coercivity and remanence of the film, i.e., a finite ANE electric field is observed even in zero magnetic field. Figure 5(d) shows the amorphous Sm deposited on the PEN substrate. 20 Co 80 The figure shows the results of observing the ANE voltage signal from the above experimental setup of the film. The horizontal axis is the heat flow density J in the direction penetrating the sample surface. Q By narrowing the wire width of each thermocouple and the spacing between adjacent wires, the output voltage can be increased. Figure 5(d) shows the output voltage V ANE is the heat flow density J Q This shows that the capacitance increases in proportion to V ANE / J Q represents the sensitivity as a heat flow sensor. It was found that a heat flow sensor having good sensitivity and operating in zero magnetic field could be obtained. Furthermore, rare earth intermetallic amorphous magnetic alloys such as Smp (Fe q Co 100-q ) 100-p In order to examine the optimal composition ratio of Sm p (Fe q Co 100-q ) 100-p The film containing the amorphous composition gradient material with p set to 20 and q changed from 0 to 100 (hereinafter referred to simply as "amorphous Sm 20 (Fe q Co 100-q ) 80 We fabricated a compositionally graded film (also called a "compositionally graded film") and evaluated its physical properties (structure and thermoelectric performance).

[0030] (amorphous Sm 20 (Fe q Co 100-q ) 80 (0≦q≦100) Compositionally graded film and its structure) FIG. 6(a) shows an embodiment of the present invention. 20 (Fe q Co 100-q ) 80 (0≦q≦100) This is a schematic cross-sectional view showing the laminated state of a compositionally graded film. On an MgO substrate, 100 layers are laminated, each layer being 0.37 nm thick Sm layer and a compositionally graded layer made of a compositionally graded material of Fe and Co and 0.63 nm thick, for a total thickness of 1 nm. An aluminum thin film is evaporated onto the top layer to prevent oxidation. In reality, due to manufacturing errors, the amorphous Sm 20 (Fe q Co 100-q )80(0≦q≦100)The composition ratio of the composition gradient film is Sm 20 Co 80 From Sm 17 Fe 83 It changed to.

[0031] Figure 6(b) shows amorphous Sm 20 (Fe q Co 100-q ) 80(0≦q≦100) XRD patterns of the compositionally graded film with different q values ​​are shown. The XRD patterns at different q values ​​confirmed that all compositions were in the amorphous phase. Figure 6(c) shows a cross-sectional bright-field (BF)-STEM image to confirm the results obtained by XRD shown in Figure 6(b). Figure 6(d) shows the microbeam electron diffraction pattern to confirm the results obtained by XRD shown in Figure 6(b). As can be seen from Fig. 6(c) and Fig. 6(d), amorphous Sm 20 (Fe q Co 100-q ) 80 It was confirmed that all of the (0≦q≦100) compositionally graded films were in the amorphous phase.

[0032] (amorphous Sm 20 (Fe q Co 100-q ) 80 (0≦q≦100) Compositionally graded films and their thermoelectric effects) Figure 7 shows the amorphous Sm on an MgO substrate. 20 (Fe q Co 100-q ) 80 This shows the composition dependence of the temperature change per unit charge current density due to the anomalous Ettingshausen effect in a compositionally graded film (0≦q≦100). In the region of 0at%≦Fe≦90at%, when a current is passed, a heat flow is generated in a direction perpendicular to both the current and magnetization, and a temperature change is observed. In particular, a large temperature change is observed in the region of Fe=5-45at%, and the maximum is observed at 10-35at%. The alloy composition range suitable for thermoelectric applications is at least the range of 0≦q≦100, where a large anomalous Nernst effect is shown, but the above results suggest that a sufficiently large anomalous Nernst effect exists due to the reciprocal relationship between the anomalous Ettingshausen effect and the anomalous Nernst effect, and therefore the range of 0≦q≦90 is preferable, the range of 5≦q≦45 is more preferable, and the range of 10≦q≦35 is even more preferable. Next, amorphous Sm within the preferred composition range 20 (Fe q Co 100-q )80 (0≦q≦100) As a film, amorphous Sm 20 (Fe 23 Co 77 ) 80 A film (thermoelectric material) was produced, and the thermoelectric performance of a thermoelectric generation element using this was evaluated.

[0033] (amorphous Sm 20 (Fe 23 Co 77 ) 80 Evaluation of the thermoelectric performance of the film) FIG. 8(a) shows the amorphous Sm 20 (Fe 23 Co 77 ) 80 1 shows a schematic diagram of the membrane manufacturing process. Figure 8(b) shows the evaporated Sm 20 (Fe 23 Co 77 ) 80 The magnetic field dependence curve of the in-plane magnetization of the film is shown in Fig. 8(b). 20 (Fe 23 Co 77 ) 80 It is seen that the film also exhibits a large coercive force and a large ratio of residual magnetization to saturation magnetization when a magnetic field is applied in-plane. Figure 8(c) shows the external magnetic field dependence of the ANE voltage when the heater output is changed. In the experiments shown in Figures 8(c) and (d), a magnetic field was applied perpendicular to the film surface, creating a temperature gradient in the in-plane direction. The reason is the same as in Figures 4(c) and (d). Figure 5(c) shows that the ANE electric field shows an odd dependence on the magnetic field, and the amorphous Sm 20 (Fe 23 Co 77 ) 80 It can be seen that when the magnetization of the film is saturated, the electric field is also saturated. Furthermore, the electric field increases when the heater power is increased (in Fig. 5(c), the darkest line shows the results when the heater power is high, and the lightest line shows the results when the heater power is low). These behaviors are consistent with ANE. However, because the magnetic field is applied perpendicular to the film surface, no coercive force or residual magnetization is observed. Figure 8(d) shows the temperature gradient dependence of the ANE voltage.20 (Fe 23 Co 77 ) 80 The abnormal Nernst coefficient of the thin film of the composition is 1.55 μV / K. From the above, the amorphous Sm of the present invention p (Fe q Co 100-q ) 100-p (0 < p ≤ 50, 0 ≤ q ≤ 100) It was found that high thermoelectric power can be obtained in the thermoelectric material composed of the film.

[0034] <Second Embodiment> FIG. 9 shows a schematic of a multilayer thermopile structure using the present material and another magnetic material having a giant abnormal Nernst effect, showing the second embodiment of the present invention. FIG. 9(a) is a diagram for explaining a multilayer thermoelectric power generation element 30 using the thermoelectric conversion material of the present invention. The multilayer thermoelectric power generation element 30 shown in FIG. 9(a) has a substrate 33, a multilayer thermoelectric body 31 and a connector 32 disposed on the substrate 33, and a connection terminal 34.

[0035] The multilayer thermoelectric body 31 has a laminated structure including a first magnetic material layer 311 made of a rare earth-based intermetallic amorphous magnetic alloy, which is the same material as the thermoelectric body 11, and a second magnetic material layer 312 made of a magnetic material having an abnormal Nernst effect, which is different from the rare earth-based intermetallic amorphous magnetic alloy constituting the thermoelectric body 11. The first magnetic material layer 311 exhibits a large abnormal Nernst effect. The abnormal Nernst coefficient (thermoelectric power) of the first magnetic material layer 311 is preferably 1 μV / K or more, and the abnormal Nernst coefficient does not necessarily have to be huge. Since the first magnetic material layer 311 has strong magnetic anisotropy in the in-plane direction of the thin film, it has an axis of easy magnetization showing a large coercive force and a residual magnetization ratio with respect to the in-plane magnetic field. Therefore, the first magnetic material layer 311 can generate a thermoelectromotive force in a zero magnetic field. In such a first magnetic material layer 311, the coercive force is preferably 10 mT or more, and the residual magnetization ratio is preferably 0.3 or more. The second magnetic material layer 312 exhibits a giant anomalous Nernst effect and is composed of a magnetic material with a large anomalous Nernst coefficient. The anomalous Nernst coefficient (thermoelectric power) of the second magnetic material layer 312 is larger than that of the first magnetic material layer 311, and is preferably, for example, 5 μV / K or more. Since the second magnetic material layer 312 has weak in-plane magnetic anisotropy, the residual magnetization significantly decreases due to thick film formation or wire thinning alone. Therefore, the second magnetic material layer 312 does not operate in a zero magnetic field. Therefore, when both the first magnetic material layer 311 and the second magnetic material layer 312 made of a rare-earth-based metallic amorphous magnetic alloy are joined, the second magnetic material layer 312, which exhibits a giant anomalous Nernst coefficient due to exchange coupling, can be magnetized in one direction even in a zero magnetic field. Thus, it becomes possible to achieve both zero magnetic field operation and a large anomalous Nernst coefficient. Examples of the magnetic material of the second magnetic material layer 312 include Fe-Ga alloys, Fe-Al alloys, Heusler alloys such as Co2MnGa, and antiferromagnets such as YbMnBi2. Also, for the connector 32, the same material as that of the connector 12 is used, but a rare-earth-based metallic amorphous magnetic alloy such as Sm p Co 100-p (0 < p ≤ 50) may be used. If the magnetization direction of the connector 32 can be made opposite to the magnetization direction of the multilayer thermoelectric body 31, the connector 32 may be composed of the same laminate as the multilayer thermoelectric body 31. Note that the arrangements of the multilayer thermoelectric body 31 and the connector 32 may be interchanged. On the other hand, for the substrate 33, the same material as that of the substrate 13 is used. The connection terminal 34 is made of the same material as the connector 32 here and is provided at both ends of the multilayer thermoelectric body 31. The connection terminal 34 may be composed of the same laminate as the multilayer thermoelectric body 31. In FIG. 9(a), the material of the first magnetic material layer 311 is denoted as Material A, the material of the second magnetic material layer 312 is denoted as Material C, and the material of the connector 32 is denoted as Material B.

[0036] The multilayer thermoelectric body 31 is formed on the substrate 33 as an amorphous Sm 20 Co80 The multilayer thermoelectric element 31 is formed by forming a thin film of a rare earth intermetallic amorphous magnetic alloy such as CrN, etc., and a different magnetic material into a thin wire. The device shown in Fig. 9(a) is magnetized in the same direction as shown in Fig. 1(a). The multilayer thermoelectric element 31 is configured to generate electricity in the direction of the electric field shown in Fig. 1(a) (the longitudinal direction of the multilayer thermoelectric element 31 and the connector 32) in response to a temperature difference in a direction perpendicular to the magnetization direction (the direction of the heat flow shown in Fig. 1(a)) due to the anomalous Nernst effect.

[0037] The connectors 32 are arranged on the surface of the substrate 33 in parallel to each of the multilayer thermoelectric bodies 31, 31, .... One connector 32 is arranged between a pair of adjacent multilayer thermoelectric bodies 31, 31, and the connector 32 electrically connects one end side of one multilayer thermoelectric body 31 to the other end side of the other multilayer thermoelectric body 31. As a result, the multilayer thermoelectric bodies 31 are electrically connected in series by the connectors 32.

[0038] As described above, the multilayer thermoelectric generating element 30 is made of amorphous Sm 20 Co 80 The multi-layer thermoelectric body 31 is made of a rare earth intermetallic amorphous magnetic alloy such as Sm and a different magnetic material. 20 Co 80 According to the multilayer thermoelectric body 31 constituted by a rare earth intermetallic amorphous magnetic alloy such as those mentioned above and a different magnetic material, it is possible to increase the effective length in the electric field direction and increase the thermoelectromotive force. Therefore, according to the present embodiment, by using such a multilayer thermoelectric body 31, it is possible to provide a multilayer thermoelectric generating element 30 that can be easily put into practical use.

[0039] 9(b) is a diagram illustrating a multilayer thermoelectric generation element 40 using the thermoelectric conversion material of the present invention. The multilayer thermoelectric generation element 40 shown in FIG. 9(b) has a substrate 43, a multilayer thermoelectric body 41 and a connector 42 arranged on the substrate 43, and a connection terminal 44. The multilayer thermoelectric body 41 is composed of a first magnetic material layer 412 made of the same material as the thermoelectric body 11, and a second magnetic material layer 411 made of a magnetic material having a huge anomalous Nernst effect different from that of the thermoelectric body 11. In the embodiment shown in Fig. 9(b), the lamination order of the first magnetic material layer 412 and the second magnetic material layer 411 is reversed compared to the embodiment shown in Fig. 9(a).

[0040] The same material as connector 32 is used for connector 42. The same material as connector 32 is used for substrate 43. The same material as substrate 13 is used for connection terminals 44, which are made of the same material as connector 42, and are provided on both ends of multilayer thermoelectric body 41. Connection terminals 44 may be formed of the same laminate as multilayer thermoelectric body 41. The connectors 42 are arranged on the surface of the substrate 43 in parallel to each of the multilayer thermoelectric elements 41, 41, .... One connector 42 is arranged between a pair of adjacent multilayer thermoelectric elements 41, 41, and the connector 42 electrically connects one end of one thermoelectric element 1 to the other end of the other thermoelectric element 1. As a result, the multilayer thermoelectric elements 41 are electrically connected in series by the connectors 42.

[0041] As described above, the multi-layer thermoelectric generating element 40 is made of amorphous Sm 20 Co 80 The multi-layer thermoelectric body 42 is made of a rare earth intermetallic amorphous magnetic alloy such as Sm and a different magnetic material. 20 Co 80 According to the multilayer thermoelectric element 41 made of a magnetic material different from the above, it is possible to increase the effective length in the electric field direction and increase the thermoelectromotive force. Therefore, according to the present embodiment, by using such a multilayer thermoelectric element 41, it is possible to provide a multilayer thermoelectric generation element 40 that can be easily put into practical use.

[0042] The rare earth intermetallic amorphous magnetic alloys and other magnetic materials used in the multilayer thermoelectric elements 31, 41 and the connectors 32, 42 exhibit finite coercive force and remanent magnetization, so that the magnetization direction of each wire can be controlled individually, and a thermopile element can be realized using a single material. The magnetization of each layer can be controlled by utilizing a local magnetic field or the exchange bias effect by adding a pinning layer such as Cr. [Industrial Applicability]

[0043] According to the thermoelectric element of the present invention, by connecting the magnetic material exhibiting the anomalous Nernst effect and the connector in a zigzag pattern, it is possible to increase the effective length in the electric field direction and increase the thermoelectromotive force, and the thermoelectric element is suitable for use in a thermoelectric power generation element utilizing the anomalous Nernst effect. The thermoelectric body of the present invention uses a rare earth intermetallic amorphous magnetic alloy that can be fabricated at room temperature using magnetron sputtering, deposition, or other methods on any type of substrate, including flexible substrates. Therefore, it can be used universally in various types of thermopile structures. The thermoelectric body of the present invention can also be used to realize a bendable thermoelectric generator or a bendable heat flow sensor.

[0044] The multilayer thermoelectric element of the present invention can increase the effective length in the electric field direction and increase the thermoelectromotive force by connecting a magnetic material exhibiting the anomalous Nernst effect and a second magnetic material layer in a zigzag pattern, and is suitable for use in thermoelectric power generation elements and heat flow sensors that utilize the anomalous Nernst effect. [Explanation of symbols]

[0045] 10, 20 Thermoelectric power generation element 11, 21 Thermoelectric body 12 Connectors 13, 23 Board 14, 24 terminals 22 Reverse magnetization connector 30, 40 Multilayer thermoelectric generation element 31, 41, 51 Multilayer thermoelectric body 311, 412 First magnetic material layer 312, 411 Second magnetic material layer 32, 42 Connector 33, 43 board 34, 44 terminals

Claims

1. A thermoelectric material that is a magnetic film and is used in a thermoelectric generating element that operates without an external magnetic field by utilizing the anomalous Nernst effect, A thermoelectric material having an axis of easy magnetization in an in-plane direction, having an amorphous structure, and containing Sm p Co 100-p (0<p≦40) or Sm p (Fe q Co 100-q ) 100-p (0<p≦40, 0≦q≦100).

2. Sm ｐ Co １００－ｐ 2. The thermoelectric element according to claim 1, wherein 15≦p≦35.

3. The thermoelectric material according to claim 2, characterized in that in Sm p Co 100-p, 20≦p≦30.

4. Sm ｐ (Fe ｑ Co １００－ｑ ) １００－ｐ 2. The thermoelectric element according to claim 1, wherein 15≦p≦35 and 5≦q≦45.

5. The thermoelectric material according to claim 4, wherein in Sm p (Fe q Co 100-q ) 100-p , 20≦p≦30 and 10≦q≦35.

6. A thermoelectric element according to any one of claims 1 to 5, and a substrate supporting the thermoelectric element.

7. a first magnetic material layer made of a rare earth intermetallic amorphous magnetic alloy containing Sm p Co 100-p (0<p≦40) or Sm p (Fe q Co 100-q ) 100-p (0<p≦40, 0≦q≦100), which has an easy axis of magnetization that exhibits a large coercive force and a large ratio of remanent magnetization to saturation magnetization in an in-plane direction and exhibits a large anomalous Nernst effect; The rare earth intermetallic amorphous magnetic alloy material exhibits a large anomalous Nernst effect, and a second magnetic material layer made of a different magnetic material has a laminated structure. Multilayer thermoelectric body.

8. The large coercive force refers to a coercive force of 10 mT or more. The large residual magnetization ratio to the saturation magnetization is 0.3 or more, The large anomalous Nernst effect means a thermoelectric power of 1 μV / K or more. The giant anomalous Nernst effect refers to a thermoelectric power of 5 μV / K or more. The multi-layer thermoelectric element of claim 7.

9. A multilayer thermoelectric body according to claim 7 or 8; and a substrate supporting the multilayer thermoelectric body.

10. A bendable thermoelectric generator using the thermoelectric generating element according to claim 6.

11. A bendable heat flow sensor using the thermoelectric generating element according to claim 6.

12. A bendable thermoelectric generator using the multilayer thermoelectric generating element according to claim 9.

13. A flexible heat flow sensor using the multilayer thermoelectric generating element according to claim 9.

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