Method for manufacturing abnormal nernst effect material, method for manufacturing thermoelectric conversion module, and method for manufacturing heat flow sensor

Abstract

To provide a manufacturing method capable of manufacturing an abnormal Nernst effect material with a small number of steps, and a manufacturing method for a thermoelectric conversion module and a manufacturing method for a heat flow sensor using the same.SOLUTION: A method for manufacturing an abnormal Nernst effect material in which a film of a metal material exhibiting an abnormal Nernst effect is formed on a substrate by wet plating under a magnetic field, includes a step a of forming an insulating layer 102 on the surface of a substrate 101, a step b of forming a connection layer 103 on the surface of the insulating layer 102, a step c of forming an electrode layer 104 on the surface of the connection layer 103, and a step d of forming a film 105 of a metal material on the surface of the electrode layer 104 by electroplating under a magnetic field (magnetic field plating step).SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing an anomalous Nernst effect material, a method for manufacturing a thermoelectric conversion module, and a method for manufacturing a heat flow sensor. [Background technology]

[0002] Thermoelectric conversion modules are being actively developed to utilize unused thermal energy. Well-known thermoelectric conversion modules use the Seebeck effect, which can generate voltage from a temperature gradient.

[0003] In the Seebeck effect, a voltage is generated in the same direction as the temperature gradient, so thermoelectric conversion modules using the Seebeck effect have a complex three-dimensional structure. For this reason, it is difficult to make thermoelectric conversion modules using the Seebeck effect large-area or film-like. In addition, thermoelectric conversion modules using the Seebeck effect use rare materials, which poses the issue of high manufacturing costs. There are also issues from the viewpoint of toxicity.

[0004] In recent years, thermoelectric conversion modules have been proposed that use anomalous Nernst effect materials that generate electromotive force due to the anomalous Nernst effect. The anomalous Nernst effect is a phenomenon in which, when a heat flow is passed through a magnetic material, causing a temperature difference, a voltage is generated in a direction perpendicular to both the magnetization direction and the temperature gradient.

[0005] The anomalous Nernst effect generates a voltage in a direction perpendicular to the temperature gradient. Therefore, a thermoelectric conversion module utilizing the anomalous Nernst effect can be deployed along a heat source, which has the advantage that it can be easily made into a large area and a film.

[0006] The anomalous Nernst effect has been reported in various materials, including Co2MnGa, Fe3Ga, Fe3Al, Mn3Ge, Mn3Sn, Mn2Ga, MnGe, Co, Fe, Nd2Mo2O7, Pt / Fe multilayers, and L1-FePt alloys.

[0007] In Non-Patent Document 1, a film of Co or Fe is formed on a substrate by sputtering, and magnetization is introduced by an external magnetic field to form an anomalous Nernst effect material. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] TCchuang et al., Phys.Rev.B, 96, 174406 (2017) Summary of the Invention [Problem to be solved by the invention]

[0009] However, the method described in Non-Patent Document 1 requires two or more steps, a film formation step and a magnetization introduction step, and thus the number of steps is large. In addition, the sputtering method can only form a film of uniform thickness on a flat substrate. When attempting to manufacture an anomalous Nernst effect material having a curved surface, it is necessary to bend the substrate after forming the film on the flat substrate, which further increases the number of steps. In addition, there is a risk that a part of the film may peel off from the substrate when bending the substrate.

[0010] An object of the present invention is to provide a manufacturing method capable of manufacturing an anomalous Nernst effect material with a small number of steps, and a manufacturing method for a thermoelectric conversion module and a manufacturing method for a heat flow sensor using the same. [Means for solving the problem]

[0011] The present invention has the following aspects. [1] A method for manufacturing anomalous Nernst effect materials, in which a film of a metal material that exhibits the anomalous Nernst effect is formed on a substrate by wet plating under a magnetic field. [2] The manufacturing method described in [1], wherein the metal material is a magnetic material having a coercive force of 3 Å or more and 10 kÅ or less. [3] The method according to [2], wherein the magnetic body has a Curie temperature of 100°C or higher. [4] The method according to any one of [1] to [3], wherein the wet plating is electroplating. [5] The manufacturing method according to any one of [1] to [4], wherein an insulating layer, a connection layer and an electrode layer are formed on the substrate in this order from the substrate side before the film of the metal material is formed. [6] The method according to any one of [1] to [5], wherein the thickness of the film of the metal material is 0.05 μm or more and 3000 μm or less. [7] A method for manufacturing a thermoelectric conversion module, comprising a step of manufacturing an anomalous Nernst effect material by the manufacturing method described in any one of [1] to [6]. [8] A method for manufacturing a heat flow sensor, comprising the step of manufacturing a thermoelectric conversion module by the manufacturing method described in [7]. Effect of the Invention

[0012] According to the present invention, it is possible to provide a manufacturing method capable of manufacturing an anomalous Nernst effect material with a small number of steps, as well as a manufacturing method for a thermoelectric conversion module and a manufacturing method for a heat flow sensor using the same. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic diagram illustrating a configuration of a thermoelectric conversion module according to a first embodiment. [Diagram 2] FIG. 5 is a schematic diagram showing the configuration of a thermoelectric conversion module according to a second embodiment. [Diagram 3] FIG. 11 is a plan view showing the configuration of a thermoelectric conversion module according to a third embodiment. [Figure 4] FIG. 13 is a schematic diagram showing the configuration of a thermoelectric conversion module according to a fourth embodiment. [Diagram 5] 1A to 1C are diagrams illustrating a method for manufacturing an anomalous Nernst effect material according to an embodiment. [Figure 6]FIG. 1 is a schematic diagram showing an example of a plating apparatus used for electroplating. [Figure 7] 11A to 11C are diagrams illustrating a method for manufacturing an anomalous Nernst effect material according to another embodiment. [Figure 8] FIG. 13 is a diagram showing the measurement results of current-voltage characteristics in an example. [Figure 9] FIG. 9 is a diagram showing the voltage dependency of the output in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The drawings used in the following description may show characteristic parts in a schematic manner for the sake of convenience in order to make the features easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not necessarily limited to them, and may be appropriately modified and implemented within the scope of the present invention.

[0015] [Anomalous Nernst effect material] First, an anomalous Nernst effect material produced by the method for producing an anomalous Nernst effect material of the present invention will be described. The anomalous Nernst effect material produced by this production method is a film of a metal material that exhibits the anomalous Nernst effect. This film is a magnetized plating film, which is formed by a plating process under a magnetic field, which will be described later. The direction of magnetization is not particularly limited, but may be, for example, the in-plane direction of the film.

[0016] The term "metallic material" refers to an elemental metal or an alloy. An elemental metal is made of one metal element. An alloy is made of two or more metal elements, or made of one or more metal elements and one or more nonmetallic elements. The metallic material may contain other elements as long as the effects of the present invention are achieved. The metal material constituting the film may be any material that exhibits the anomalous Nernst effect when magnetized, and is typically a magnetic material.

[0017] As the metal material, a magnetic material having a coercive force of 3 Oe (Oersted) or more and 10 kOe or less is preferable. The coercive force of the magnetic material is more preferably 10 Oe or more, even more preferably 30 Oe or more, particularly preferably 50 Oe or more, and most preferably 70 Oe or more. Also, it is more preferably 5 kOe or less, even more preferably 2 kOe or less, particularly preferably 500 Oe or less, and most preferably 100 Oe or less. The lower limit and the upper limit can be appropriately combined. If the coercive force is equal to or greater than the lower limit, it is sufficiently large against the earth's magnetic field, so that the magnetization of the anomalous Nernst effect material can be prevented from disappearing naturally. On the other hand, if the coercive force is equal to or less than the upper limit, sufficient magnetization can be introduced by the magnetic field of a standard scale magnet. Although the coercivity is greatly affected by factors such as the grain size of the sample, examples of magnetic materials that exhibit a coercivity between 3 Å and 10 kÅ e include cobalt, iron, samarium-cobalt magnets, ferrite magnets, and alnico magnets. Coercive force is defined as the strength of the external magnetic field when a magnetic field in the opposite direction is applied to a magnetized magnetic material and the residual magnetization becomes zero. For example, the value described in the Electrical and Electronic Materials Handbook (edited by Ieda Masayuki, Takahashi Kiyoshi, Narita Masahito, and Yanagihara Kotaro, first edition, first printing, November 15, 1987, Asakura Publishing) can be used.

[0018] The magnetic material preferably has a Curie temperature of 100°C or higher. The Curie temperature of the magnetic material is more preferably 200°C or higher, further preferably 500°C or higher, and particularly preferably 1000°C or higher. The Curie temperature is the transition temperature at which a ferromagnetic material changes into a paramagnetic material. When the temperature of the anomalous Nernst effect material exceeds the Curie temperature, the magnetization disappears, and the magnetization does not recover even if the temperature is subsequently lowered. If the Curie temperature of the magnetic material is equal to or higher than the lower limit, the magnetization is unlikely to disappear when the anomalous Nernst effect material is applied to a power generation module or a heat flow sensor. The higher the Curie temperature of the magnetic material, the more preferable it is, and the upper limit is not particularly limited, but is, for example, 1200°C. Examples of magnetic materials with a Curie temperature of 100°C or higher include cobalt (Curie temperature 1115°C), iron (Curie temperature 770°C), samarium-cobalt magnets (Curie temperature 820°C), ferrite magnets (Curie temperature 450°C), and alnico magnets (Curie temperature 850°C). The Curie temperature is a value specific to a substance, and for example, the value described in Electrical and Electronic Materials Handbook (edited by Ieda Masayuki, Takahashi Kiyoshi, Narita Masahito, and Yanagihara Kotaro, first edition, first printing, November 15, 1987, Asakura Publishing) can be adopted.

[0019] The residual magnetic flux density (residual magnetization) of a magnetic material is greatly affected by the thickness of the sample and the microstructure within the sample, but is preferably 100 Oe or more, more preferably 300 Oe or more. The magnitude of the voltage output due to the anomalous Nernst effect is proportional to the magnitude of magnetization, and in order to obtain a voltage output even when the external magnetic field is zero, a residual magnetic flux density is necessary, and a larger value of the residual magnetic flux density will result in a larger voltage output. There is no particular upper limit for the residual magnetic flux density. Examples of magnetic materials with a residual magnetic flux density of 100 Oe or more include cobalt (4900 Oe), samarium-cobalt magnets (up to 1000 Oe), ferrite magnets (2000 Oe or more), and alnico magnets (up to 10000 Oe).

[0020] The electrical resistance of the metal material at 25°C is preferably 1000 μΩ·cm or less, and more preferably 500 μΩ·cm or less. If the electrical resistance is equal to or less than the upper limit, it is possible to suppress loss due to internal resistance when processed into a power generation module. The lower the electrical resistance, the better, and the lower limit is not particularly limited, but is, for example, 1 μΩ·cm. The electrical resistance is measured by the four-terminal method.

[0021] For a metal material, the thermal conductivity at 25°C is preferably small when it is intended to obtain a high amount of power generation as a power generation module, or when it is intended to obtain high sensitivity as a heat flow sensor, specifically, 150 W / mK or less is preferable, more preferably 120 W / mK or less, and usually 2 W / mK or more. On the other hand, for a heat flow sensor, the thermal conductivity is preferably large so as not to disturb the environment of the measurement target, specifically, 5 W / mK or more is preferable, more preferably 10 W / mK or more, and usually 300 W / mK or less. Thermal conductivity is measured by a steady-state method such as a heat flow meter method, or a non-steady-state method such as a laser flash method.

[0022] Anomalous Nernst coefficient S of metallic materials ANE The absolute value of is preferably 0.3 μV / K or more, more preferably 0.5 μV / K or more. The anomalous Nernst coefficient S ANE is an index of the anomalous Nernst effect. The anomalous Nernst coefficient S ANE The larger the absolute value of , the larger the voltage output when a temperature difference is applied. Anomalous Nernst coefficient S of metallic materials ANE The larger the absolute value of is, the better. On the other hand, the anomalous Nernst coefficient S ANE For materials with an absolute value of too large, unless the anomalous Nernst effect material is made into an extremely thin film (e.g., 0.1 μm or less), the residual magnetization is often almost zero (i.e., the anomalous Nernst effect is not exhibited without an external magnetic field), so it is preferable that the absolute value be 5 μV / K or less.

[0023] Anomalous Nernst coefficient S of metallic materials ANE is calculated as follows: A flat metal material (length L: 8 mm, width W: 1.5 mm, thickness t: 1 mm) is used as a sample, and one end of the sample is heated by a heater and the other end is brought into contact with a heat sink, creating a temperature difference along the side L of the sample. This gives the sample a uniform temperature gradient, and the temperature difference ΔT (K) at two points separated by L_temp (mm) is measured. A magnetic field is applied in a direction perpendicular to this temperature difference, and the voltage V generated at two points separated by a distance W_volt (mm) in a direction perpendicular to both the temperature difference and the magnetic field is measured, and the anomalous Nernst coefficient S is calculated using the following equation (1). ANE Calculate. S ANE =(V / ΔT)×(L_temp / W_volt)···(1)

[0024] From the viewpoint of developing remanent magnetization, the metal material preferably contains at least one element selected from the group consisting of Co, Fe, and Ni. The metal material containing at least one element selected from the group consisting of Co, Fe, and Ni may further contain other elements in addition to Co, Fe, and Ni, such as B, Sm, Nd, Cu, Al, and O. As for the composition of the metal material, it is preferable that at least one selected from the group consisting of Co, Fe, and Ni accounts for 30 atm% or more, more preferably 50 atm% or more, and even more preferably 80 atm% or more, of all atoms (100 atm%) constituting the metal material. Examples of metal materials containing at least one element selected from the group consisting of Co, Fe, and Ni include Co, Fe, Ni, a Co-Ni alloy, a Co-Fe alloy, a Sm-Co alloy, Fe oxide, Fe2O3, and an Al-Ni-Co-Cu-Fe alloy.

[0025] The film of the metallic material as the anomalous Nernst effect material is magnetized.

[0026] The thickness of the metal film, that is, the thickness of the anomalous Nernst effect material, can be set as appropriate, but is preferably 0.05 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, and also preferably 3000 μm or less, more preferably 1000 μm or less, and even more preferably 500 μm or less. The lower limit value and the upper limit value can be combined as appropriate. If the thickness of the anomalous Nernst effect material is equal to or greater than the lower limit value, when a heat flow is caused to flow in the thickness direction, the output (power) is proportional to the volume of the anomalous Nernst effect material, so that it is possible to obtain, for example, power sufficient to drive a self-powered heat flow sensor. A self-powered heat flow sensor is a type of heat flow sensor that supplements the power required for operation by itself, and has the advantage of eliminating the need for power supply wiring and reducing the labor costs for wiring compared to a non-self-powered type. In the case of sputtering, it is difficult to make the film thickness 1 μm or more. On the other hand, if the thickness of the anomalous Nernst effect material is less than the upper limit value, a temperature gradient will be generated within the anomalous Nernst effect material when a temperature difference is applied to the front and back of the anomalous Nernst effect material, tending to cause the anomalous Nernst effect.

[0027] The anomalous Nernst effect material may be free-standing or disposed on a substrate. In the latter case, the number of anomalous Nernst effect materials provided on the substrate may be one or more. When two or more anomalous Nernst effect materials are provided on the substrate, the two or more anomalous Nernst effect materials may be electrically connected to each other.

[0028] The material of the substrate is not particularly limited, and examples thereof include Si, Al, Cu, glass, and resin. When the anomalous Nernst effect material is used integrally with the substrate, the substrate is preferably made of a material having a high thermal conductivity. The shape of the substrate is not particularly limited, and examples thereof include a plate, a film, and a cylinder. A plate-shaped substrate may be flat or curved. The thickness of the substrate is, for example, 0.1 to 3 mm.

[0029] There may be other layers between the substrate and the anomalous Nernst effect material. The other layer may be, for example, a layer that is known to be provided on the substrate beforehand when wet plating is performed. For example, when the wet plating is electroplating, an electrode layer is provided on the substrate as necessary. The electrode layer functions as a cathode in the electroplating. In addition, an insulating layer may be provided between the substrate and the electrode layer to electrically separate the substrate and the electrode layer. By electrically separating the substrate and the electrode layer, the voltage signal of the anomalous Nernst effect material can be extracted without any problem even if the substrate is a conductor. A connection layer may be provided between the insulating layer and the electrode layer, and the connection layer can fix the insulating layer and the electrode layer so that they do not peel off from each other. When an insulating base material is used, the insulating layer does not need to be provided.

[0030] Anomalous Nernst effect materials are used, for example, in thermoelectric conversion modules. Fig. 1 is a schematic diagram showing the configuration of a thermoelectric conversion module 100 according to the first embodiment. As shown in Fig. 1, the thermoelectric conversion module 100 includes an anomalous Nernst effect material 1, a first electrode 11, a second electrode 12, and a magnetic field application means 20. The anomalous Nernst effect material 1 is an anomalous Nernst effect material manufactured by the manufacturing method of the anomalous Nernst effect material of the present invention.

[0031] The first electrode 11 is electrically connected to the anomalous Nernst effect material 1. The material of the first electrode 11 is not particularly limited as long as it has electrical conductivity. For example, the material of the first electrode 11 may be metal such as Au, Ag, Cu, or Al.

[0032] The second electrode 12 is electrically connected to the anomalous Nernst effect material 1. The material of the second electrode 12 is not particularly limited as long as it has electrical conductivity. For example, the material of the second electrode 12 may be a metal such as Au, Ag, Cu, or Al.

[0033] There is no particular limitation on the arrangement of the first electrode 11 and the second electrode 12. However, if there is a difference in temperature between the first electrode 11 and the second electrode 12, the Seebeck effect will be superimposed in addition to the anomalous Nernst effect, so for the heat flow sensor, it is preferable that the first electrode 11 and the second electrode 12 are arranged so that they are the same distance from the heat source.

[0034] The magnetic field application means 20 is not particularly limited as long as it can apply a magnetic field in a direction perpendicular to the direction in which the temperature difference occurs and the direction in which the electromotive force is generated (the direction connecting the first electrode 11 and the second electrode 12). The magnetic field application means 20 is, for example, a permanent magnet, an electromagnet, or the like.

[0035] As shown in FIG. 1, the thermoelectric conversion module 100 has a rectangular parallelepiped anomalous Nernst effect material 1 extending in one direction (Y direction in this embodiment), has a thickness of 0.1 μm or more in the thickness direction (Z direction in this embodiment), and is magnetized in the +X direction. The magnetic field is applied by a magnetic field application means 20. A known method can be used to apply the magnetic field. It should be noted that since the anomalous Nernst effect material produced by the production method of the present invention is magnetized during production, application of a magnetic field by the magnetic field application means 20 is not necessarily required.

[0036] When a heat flow Q flows through the anomalous Nernst effect material 1 in a direction (+Z direction in this embodiment) perpendicular to the direction of magnetization M (+X direction), a temperature difference ΔT occurs in the +Z direction. As a result, in the anomalous Nernst effect material 1, an electromotive force is generated in a direction (Y direction in this embodiment) perpendicular to both the direction of the heat flow Q (+Z direction) and the direction of the magnetization M (+X direction) due to the anomalous Nernst effect. This allows the anomalous Nernst effect material 1 to perform thermoelectric conversion.

[0037] 2 is a schematic diagram showing the configuration of a thermoelectric conversion module 100A according to the second embodiment. As shown in FIG. 2, the thermoelectric conversion module 100A includes a substrate 30 and a power generation body 40 disposed on the substrate 30.

[0038] The substrate 30 has a first surface 30a on which the power generating body 40 is disposed, and a second surface 30b opposite to the first surface 30a. For example, the second surface 30b receives heat from a heat source (not shown). The material of the substrate 30 is the same as the material of the base material described above. The material of the substrate 30 preferably has high thermal conductivity.

[0039] The first electrode 11A is electrically connected to one end of the power generation body 40. The material of the first electrode 11A is not particularly limited as long as it has electrical conductivity. For example, the material of the first electrode 11A may be metal such as Au, Ag, Cu, or Al.

[0040] The second electrode 12A is electrically connected to the other end of the power generation body 40. The material of the second electrode 12A is not particularly limited as long as it has electrical conductivity. For example, the material of the second electrode 12A may be metals such as Au, Ag, Cu, and Al.

[0041] The power generating body 40 has one or more first anomalous Nernst effect materials 41 and one or more second anomalous Nernst effect materials 42. The first anomalous Nernst effect materials 41 and the second anomalous Nernst effect materials 42 may be the same as the anomalous Nernst effect material 1 described above.

[0042] One or more first anomalous Nernst effect materials 41 and one or more second anomalous Nernst effect materials 42 extend in one direction (here, the Y direction) within the plane of the first surface 30a and are arranged alternately in another direction (here, the X direction) that intersects with this one direction (orthogonal in this embodiment).

[0043] The first anomalous Nernst effect material 41 has a first connection portion 41a protruding from one end (end on the +Y side) in one direction (Y direction) toward one side (-X side) in the other direction (X direction). On the other hand, the second anomalous Nernst effect material 42 has a second connection portion 42a protruding from the other end (end on the -Y side) in the one direction (Y direction) toward one side (-X side) in the other direction (X direction).

[0044] The first anomalous Nernst effect material 41 is electrically connected to one end (end on the +Y side) in one direction (Y direction) of the second anomalous Nernst effect material 42 via a first connection portion 41a. On the other hand, the second anomalous Nernst effect material 42 is electrically connected to the other end (end on the -Y side) of the first anomalous Nernst effect material 41 via a second connection portion 42a.

[0045] As a result, in the power generating body 40, the first anomalous Nernst effect material 41 and the second anomalous Nernst effect material 42 adjacent to each other are electrically connected in series, so that the power generating body 40 has a meandering shape.

[0046] In the power generating body 40, the first anomalous Nernst effect material 41 is arranged so that the direction of magnetization M1 (in this embodiment, the -X direction) and the direction of magnetization M2 (in this embodiment, the +X direction) of the second anomalous Nernst effect material 42 are opposite to each other.

[0047] In the thermoelectric conversion module 100A, when a heat flow Q flows from the second surface 30b side of the substrate 30 toward the power generator 40, a temperature difference occurs in the power generator 40 in the direction of the heat flow, and a voltage V is generated in the power generator 40 due to the anomalous Nernst effect.

[0048] When the second surface 30b of the substrate 30 receives heat from the heat source, a heat flow Q flows in the +Z direction toward the power generator 40. At this time, in the first anomalous Nernst effect material 41, an electromotive force E1 is generated in a direction (+Y direction) perpendicular to both the direction of the magnetization M1 (-X direction) and the direction of the heat flow Q (+Z direction). On the other hand, in the second anomalous Nernst effect material 42, an electromotive force E2 is generated in a direction (-Y direction) perpendicular to both the direction of the magnetization M2 (+X direction) and the direction of the heat flow Q (+Z direction).

[0049] In the power generating body 40, the first anomalous Nernst effect material 41 and the second anomalous Nernst effect material 42 adjacent to each other are electrically connected in series. Therefore, the electromotive force E1 generated in the first anomalous Nernst effect material 41 and the electromotive force E2 generated in the second anomalous Nernst effect material 42 are added together, and the output voltage V can be increased.

[0050] In the thermoelectric conversion module 100A of the present embodiment, the temperature gradient, the magnetization direction, and the voltage direction are perpendicular to each other, so that it is possible to use the first anomalous Nernst effect material 41 and the second anomalous Nernst effect material 42 in thin sheet form.

[0051] Here, assuming that the length in the longitudinal direction (extension direction) of the first anomalous Nernst effect material 41 and the second anomalous Nernst effect material 42 is L1 and the thickness (height) is H1, when the temperature difference in the first anomalous Nernst effect material 41 and the second anomalous Nernst effect material 42 is constant, the voltage V generated by the anomalous Nernst effect is proportional to L1 / H1. In other words, the longer and thinner the first anomalous Nernst effect material 41 and the second anomalous Nernst effect material 42 are, the larger the obtained voltage V becomes.

[0052] 3 is a plan view showing a configuration of a thermoelectric conversion module 100B according to a third embodiment. As shown in FIG 3, the thermoelectric conversion module 100B includes a substrate 30 and a power generation body 40B disposed on the substrate 30.

[0053] The power generating body 40B has a plurality of anomalous Nernst effect materials 45 and wiring 50.

[0054] The anomalous Nernst effect material 45 may be the same as the anomalous Nernst effect material 1. The anomalous Nernst effect materials 45 are arranged in parallel on the substrate 30 in a direction (X direction) perpendicular to the extension direction (Y direction) so that the directions of the magnetization M1A are the same (-X direction).

[0055] One end of the wiring 50 is electrically connected to one end side (-Y side) of the anomalous Nernst effect material 45, and the other end is electrically connected to the other end side (+Y side) of another adjacent anomalous Nernst effect material 45. This electrically connects the anomalous Nernst effect materials 45 in series. The material of the wiring 50 is not particularly limited as long as it is conductive. For example, the material of the wiring 50 may be metal such as Au, Ag, Cu, or Al.

[0056] The heat flow Q flows from the substrate 30 side to the power generating body 40B side (flows in the +Z direction). The thermoelectric conversion module 100B can be manufactured more easily than the thermoelectric conversion module 100A because the adjacent anomalous Nernst effect materials 45 are connected via the wiring 50.

[0057] Fig. 4 is a schematic diagram showing the configuration of a thermoelectric conversion module 100C according to the fourth embodiment. As shown in Fig. 4, the thermoelectric conversion module 100C includes a substantially cylindrical hollow member 31 and a long sheet-like anomalous Nernst effect material 32 wound in a spiral shape around the outer circumferential surface of the hollow member 31.

[0058] The anomalous Nernst effect material 32 may be the same as the anomalous Nernst effect material 1. The anomalous Nernst effect material 32 is magnetized in a direction parallel to the axial direction of the hollow member 31 (X direction).

[0059] In the thermoelectric conversion module 100C, when the inside of the hollow member 31 is hotter than the outside, the heat flow P flows from the inside to the outside of the hollow member 31, and a temperature gradient (temperature difference) is generated from the inside to the outside of the hollow member 31. This generates a voltage V in the anomalous Nernst effect material 32. In this embodiment, an electromotive force is generated along the longitudinal direction of the anomalous Nernst effect material 32 (the direction perpendicular to both the magnetization direction and the heat flow direction).

[0060] In the thermoelectric conversion module 100C of this embodiment, the temperature gradient, the magnetization direction, and the voltage direction are perpendicular to each other, so that it is possible to use a thin sheet-like anomalous Nernst effect material 32.

[0061] The electromotive force generated by the anomalous Nernst effect increases as the length of the anomalous Nernst effect material increases. Therefore, in the thermoelectric conversion module 100C of this embodiment, by employing the long sheet-like anomalous Nernst effect material 32 wound in a spiral shape around the outer circumferential surface of the hollow member 31 described above, the length of the anomalous Nernst effect material can be increased, and a further increase in the voltage V can be expected.

[0062] The thermoelectric conversion module is not limited to the configurations of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the above-mentioned thermoelectric conversion modules 100, 100A, 100B, and 100C can be applied to various devices. For example, by providing the thermoelectric conversion modules 100, 100A, 100B, and 100C in a heat flow sensor, it is possible to determine whether the thermal insulation performance of a building is good or bad.

[0063] In addition, by installing thermoelectric conversion modules 100, 100A, 100B, and 100C in an exhaust device of a motorcycle or the like, electricity can be generated by utilizing the heat (waste heat) of the exhaust gas, and the thermoelectric conversion modules 100, 100A, 100B, and 100C can be effectively used as auxiliary power sources.

[0064] Further, the thermoelectric conversion modules 100, 100A, 100B, and 100C can be provided with not only the function as the thermoelectric conversion element described above, but also the function of temperature modulation (particularly cooling) by supplying electric power, like a Peltier element.

[0065] [Method of manufacturing anomalous Nernst effect material] The method for producing the anomalous Nernst effect material of the present invention includes a step of forming a film of a metal material exhibiting the anomalous Nernst effect on a substrate by wet plating in a magnetic field (magnetic field plating step). The film of the metal material formed by the plating process under a magnetic field is magnetized at the same time as the film is formed. Therefore, the film of the metal material formed exhibits the anomalous Nernst effect. Therefore, the anomalous Nernst effect material can be formed in a single process of the plating process under a magnetic field. The present manufacturing method may further include a step other than the magnetic field plating step.

[0066] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the anomalous Nernst effect material of the present invention will be described in detail with reference to the drawings. FIG. 5 is a diagram illustrating a manufacturing method according to an embodiment. The manufacturing method according to this embodiment includes the steps of: Step (a): forming an insulating layer 102 on a surface of a substrate 101; Step (b): forming a connection layer 103 on a surface of the insulating layer 102; Step (c): forming an electrode layer 104 on a surface of the connection layer 103; Step (d): forming a film 105 of a metal material on the surface of the electrode layer 104 by electroplating in a magnetic field (magnetic field plating step).

[0067] <Process (a)> The material of the insulating layer 102 is not particularly limited, and examples thereof include SiO2, Al2O3, AlN, BN, and MgO. As a method for forming the insulating layer 102, known methods such as heat treatment, coating, sputtering, etc. can be applied depending on the material of the base material 101 and the material of the insulating layer 102 to be formed. For example, when the base material 101 is a silicon base material, a thermal oxide film (SiO2 film) can be formed on the surface of the base material 101 as the insulating layer 102 by heat-treating the base material 101. Heat treatment conditions include heating at 800 to 1200°C, for example. The thickness of the insulating layer 102 is, for example, 100 nm to 1 mm. The thickness of the insulating layer 102 is measured, for example, by a cross-sectional SEM.

[0068] <Process (b)> The material of the connection layer 103 can be selected according to the material of the electrode layer 104. For example, when the electrode layer 104 is made of Cu, the material of the connection layer 103 may be Ti, Cr, or the like. The connection layer 103 can be formed by a known method such as sputtering. The thickness of the connection layer 103 is, for example, 5 to 50 nm. The thickness of the connection layer 103 is measured, for example, by cross-sectional SEM.

[0069] <Process (c)> The material of the electrode layer 104 can be selected according to the metal material to be plated in step (d). For example, when the metal material is Co, the electrode layer 104 may be made of Cu, Al, or the like. The electrode layer 104 can be formed by a known method such as sputtering. The thickness of the electrode layer 104 is, for example, 50 to 1000 nm. The thickness of the electrode layer 104 is measured by cross-sectional SEM. After the electrode layer 104 is formed, treatments such as degreasing and washing with water may be performed.

[0070] <Process (d)> Step (d) can be carried out, for example, using a plating apparatus shown in FIG.

[0071] (Plating equipment) The plating apparatus shown in FIG. 6 includes a plating tank 201 that contains a plating solution L, and a plurality of permanent magnets 202.

[0072] An anode 203 and a cathode 204 are disposed opposite each other in the plating tank 201. In this example, the cathode 204 is disposed at the bottom of the plating tank 201, and the anode 203 is disposed above the cathode 204. The anode 203 is a metal or an alloy containing metal elements that constitute a metallic material. The anode 203 is connected to an external power source (not shown). The cathode 204 is an object to be plated. The cathode 204 is disposed with the surface to be plated facing the anode 203. In this example, the laminate obtained in steps (a) to (c), in which the insulating layer 102, the connection layer 103, and the electrode layer 104 are laminated in this order on the base material 101, is the object to be plated, and the surface of the electrode layer 104 is the surface to be plated. An electrode 205 is disposed on the cathode 204. The electrode 205 is in contact with a part (e.g., the outer edge) of the surface to be plated of the cathode 204. The electrode 205 is connected to an external power source to which the anode 203 is connected, so that when a current is supplied to the anode 203, a voltage is applied to the surfaces to be plated of the anode 203 and the cathode 204.

[0073] The multiple permanent magnets 202 are arranged on both sides of the plating tank 201 in the first direction. These permanent magnets 202 are capable of applying a magnetic field along the first direction inside the plating tank 201. In this example, the first direction is a direction perpendicular to the depth direction of the plating tank 201 (the left-right direction in FIG. 6). The applied magnetic field is preferably 300 Oe or more, more preferably 500 Oe or more, and even more preferably 800 Oe or more at the center of the cathode 204 in the first direction. If the magnetic field is greater than or equal to the above numerical value, magnetization is excellently introduced into the anomalous Nernst effect material.

[0074] The plating apparatus in this example is provided with a liquid circulation mechanism for circulating the plating liquid L. The liquid circulation mechanism includes a liquid supply port 206 for supplying plating liquid L to the plating tank 201, and a liquid drainage port 207 for recovering plating liquid L discharged from the plating tank 201. The liquid supply port 206 and the liquid drainage port 207 are disposed on both sides of the plating tank 201 in the first direction. The plating solution L is transferred from a tank (not shown) to a liquid supply port 206 by a pump or the like, and is supplied to the plating tank 201 through the liquid supply port 206. This plating solution L overflows from the plating tank 201, is collected from a liquid drainage port 207, and is returned to the tank that contains the plating solution L. In this example, the plating solution L from the liquid supply port 206 is introduced into the bottom of the plating tank 201 and moves to the opposite side (first direction side) across the cathode 204. The flow of the plating solution L makes it easy for metal ions to be supplied to the vicinity of the surface of the cathode 204 . During plating, as the plating progresses, metal ions are consumed near the cathode 204. Metal ions can be supplied to the vicinity of the cathode 204 by circulating the plating solution L using a solution circulation mechanism.

[0075] The plating apparatus of this example is provided with an agitation mechanism 208 for agitating the plating tank 201 . In this example, the stirring mechanism 208 is equipped with a squeegee bar 208a that is longer than the diameter of the cathode 204. The squeegee bar 208a is adapted to reciprocate in the plating tank 201 between the anode 203 and the cathode 204 in a direction parallel to the cathode 204. During plating, metal ions are consumed near the surface to be plated as the plating progresses. By stirring the plating tank 201 with the stirring mechanism 208, metal ions can be supplied to the vicinity of the surface to be plated.

[0076] Note that, although an example of a face-up type plating apparatus in which the surface to be plated of the object to be plated faces upwards has been shown here, the plating apparatus is not limited to this, and various types of plating apparatus can be used, such as a face-down type in which the surface to be plated faces downwards, or a vertical rack type in which the surface to be plated faces sideways.

[0077] (Plating solution) The plating solution used in the electroplating can be selected from known plating solutions depending on the film of the metal material to be formed. The plating solution typically contains a metal ion source corresponding to the metal material, a conductive salt, and a pH buffer.

[0078] Known metal ion sources can be used, and examples of such sources include water-soluble metal salts. Examples of water-soluble metal salts include sulfates such as cobalt sulfate, nickel sulfate, and ferrous sulfate; sulfamates such as cobalt sulfamate, nickel sulfamate, and ferrous sulfamate; and halides such as cobalt chloride, cobalt bromide, nickel chloride, nickel bromide, and ferrous chloride. Metal ion sources may be used alone or in combination of two or more. The content of the metal ion source in the plating solution in terms of metal ions is, for example, 6 to 30 g / L.

[0079] As the conductive salt, known salts can be used, and examples thereof include water-soluble salts of metals selected from the group consisting of alkali metals and alkaline earth metals (hereinafter also referred to as "alkali (earth) metals"). Examples of water-soluble salts of alkali (earth) metals include halides, sulfates, sulfamates, and methanesulfonates. Specific examples include lithium chloride, sodium chloride, potassium chloride, magnesium chloride, sodium bromide, potassium bromide, lithium sulfate, sodium sulfate, potassium sulfate, sodium sulfamate, and potassium sulfamate. One type of conductive salt may be used alone, or two or more types may be used in combination. The content of the conductive salt in the plating solution is, for example, 150 to 800 g / L.

[0080] As the pH buffering agent, known ones can be used, for example, organic carboxylic acid and its salt, ammonium hydroxide, ammonium salt, amines, boric acid, etc. Specific examples include malic acid, ammonium malate, succinic acid, ammonium succinate, potassium acetate, sodium acetate, ammonium tartrate, ascorbic acid, citric acid, ammonium citrate, lactic acid, pyruvic acid, propionic acid, butyric acid, formic acid, acetic acid, glycolic acid, oxalacetic acid, aqueous ammonia, ethylenediamine, triethanolamine, ethanolamine, ammonium sulfate, and boric acid. One pH buffering agent may be used alone, or two or more may be used in combination. The content of the pH buffer in the plating solution is, for example, 5 to 300 g / L.

[0081] The plating solution may further contain a brightener, which can increase the hardness and brightness of the film. As the glossing agent, known ones can be used, for example, first glossing agents such as saccharin, sodium naphthalene disulfonate, sodium naphthalene trisulfonate, sodium allylsulfonate, sodium propargylsulfonate, etc., and second glossing agents such as butynediol, propargyl alcohol, coumarin, formalin, etc. The glossing agents may be used alone or in combination of two or more kinds. The brightener preferably contains a first brightener. By containing the first brightener, sulfur is introduced into the film, which has the effect of improving hardness and reducing internal stress. The content of the brightener in the plating solution is, for example, 0.01 to 2 g / L.

[0082] The pH of the plating solution is, for example, in the range of 2 to 4.5.

[0083] (Plating method) 6, an example of a plating method using the plating apparatus is to place an anode 203 and a cathode 204, which is an object to be plated, in a plating tank 201 containing a plating solution, and supply a current to the anode 203. While the current is being supplied, plating progresses, and a film 105 (anomalous Nernst effect material 1) of a magnetized metal material is formed. The plating conditions can be appropriately selected. The current density is, for example, 0.01 to 5 A / dm 2 The temperature of the plating solution is, for example, within the range of room temperature to 40°C.

[0084] During plating, it is preferable to constantly circulate the plating solution using a liquid circulation mechanism. The flow rate of the plating solution during circulation is not particularly limited, but is, for example, 10 to 15 L / min. During plating, it is preferable that the stirring mechanism 208 reciprocates the squeegee bar 208a in the vicinity of the surface of the cathode 204 in parallel to the cathode 204. The moving speed of the squeegee bar 208a is, for example, 50 to 500 mm / sec. After plating, a treatment such as washing with water may be carried out.

[0085] In this manner, a laminate is obtained in which the insulating layer 102, the connection layer 103, the electrode layer 104, and the film of a metal material 105 are laminated in this order from the substrate 101 side.

[0086] After step (d), a step of peeling off the metal material film 105 from the substrate 101 may be carried out. When the metal film 105 is peeled off from the substrate 101, the insulating layer 102, the connection layer 103, and the electrode layer 104 may each remain on the substrate 101 side, or may be peeled off from the substrate 101 together with the metal film 105.

[0087] FIG. 7 is a diagram illustrating a manufacturing method according to another embodiment. In this embodiment, a power generating element having a plurality of anomalous Nernst effect materials and wiring as shown in the third embodiment is formed on a substrate 101. The manufacturing method according to this embodiment includes the steps of: Step (a): forming an insulating layer 102 on a surface of a substrate 101; Step (b): forming a connection layer 103 on a surface of the insulating layer 102; Step (c): forming an electrode layer 104 on a surface of the connection layer 103; Step (e): covering a part of the surface of the electrode layer 104 with a resist pattern 106; Step (f): forming a film 105 of a metal material by electroplating in a magnetic field on the portion of the surface of the electrode layer 104 that is not covered with the resist pattern 106 (magnetic field plating step); Step (g): removing the electrode layer 104 and the connection layer 103 except for the portions to be left as wiring. Since steps (a) to (c) are similar to those in the embodiment shown in FIG. 5, details are omitted in FIG.

[0088] <Process (e)> In step (e), in order to define the area (film-forming area) on the surface of the electrode layer 104 where a film of a metal material is to be formed in step (f), the area other than the film-forming area (non-film-forming area) is covered with a resist pattern 106. Step (e) can be performed by a known method. For example, a resist material is applied to the surface of the electrode layer 104 to form a resist film, and the resist film is exposed through a pattern photomask, developed, and subjected to O2 ashing as necessary to form a resist pattern 106 that covers the non-film-forming region.

[0089] <Process (f)> Step (f) can be carried out in the same manner as in the above-mentioned step (d).

[0090] <Process (g)> At the stage where step (f) is completed, the spaces between adjacent metal material films 105 are filled with electrode layers 104 and connection layers 103. By removing the electrode layers 104 and connection layers 103 between the multiple metal material films 105 except for the portions to be left as wiring, the multiple anomalous Nernst effect materials can be electrically connected in series. Step (g) can be performed by a known method. For example, after the resist pattern 106 is peeled off, a resist material is applied again to form a resist film, and the resist film is exposed through a pattern photomask so that only the parts to be left as wiring are covered, developed, and O2 ashing is performed as necessary to form a resist pattern that covers only the parts to be left as wiring. Thereafter, the electrode layer 104 and the connection layer 103 that are not covered by the resist pattern are sequentially removed by etching, and the resist pattern is removed.

[0091] The present invention is not limited to the configurations of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. EXAMPLES

[0092] The effects of the present invention will be more clearly understood by the following examples. Note that the present invention is not limited to the following examples, and various modifications can be made without departing from the spirit of the present invention.

[0093] Example 1 Using the procedure shown in FIG. 7, a sample was fabricated in which a power generating body having a plurality of anomalous Nernst effect materials and wiring connecting them, as shown in the third embodiment, was formed on the first surface of a 4-inch silicon substrate. The generator was a rectangular shape measuring 0.5 mm wide and 50 mm long, with Co films magnetized in the width direction arranged at a pitch of 0.8 mm, and the upper and lower ends of adjacent Co films connected by a 0.1 mm wide Cu film.

[0094] The details of the sample preparation procedure are given below. First, a silicon substrate was treated in a thermal oxidation furnace (thermal oxidation treatment) to form a SiO2 layer (insulating layer) with a thickness of 300 nm or less. Next, a Ti layer (connecting layer) with a thickness of 20 nm was formed on the SiO2 layer by sputtering deposition, and then a Cu layer (electrode layer) with a thickness of 200 nm was formed on the Ti layer. Next, a resist (Tokyo Ohka Kogyo Co., Ltd., PMER P-BK5000) was applied onto the Cu layer and baked to form a resist film that covered the entire surface of the Cu layer. Next, to define the rectangular areas where the Co film was to be formed, the resist film was exposed through a pattern photomask, developed with a developer (aqueous tetramethylammonium hydroxide (TMAH) solution), and then subjected to O2 ashing to form a resist pattern. At this point, the Cu layer was exposed in the areas where Co was to be plated, and the other areas were covered with the resist pattern. The substrate on which the resist pattern was formed in this way was used as the substrate to be plated, and a Co film having a thickness of 10 μm was formed by plating under a magnetic field. The details of plating will be described later. Next, the resist pattern was stripped off using a resist stripper (N-342, manufactured by Nagase Chemtex Corporation). At this point, the portions between the Co films were filled with Cu and Ti without any gaps when viewed from above. Next, resist (PMER P-BK5000) was applied again and baked to form a resist film covering the Co film and the exposed Cu layer. In order to cover only the Co film and the parts of the Cu and Ti layers to be left as wiring with resist, the resist film was exposed through a pattern photomask, developed, and O2 ashed to form a resist pattern. Next, the exposed Cu layer was removed using an alkaline etching solution (Yamatoya Shokai, Alka-Etch), and the Ti layer was further removed using an etching solution (TI3991). After that, the resist pattern was removed using a resist remover (N-342) to obtain a sample.

[0095] The plating was performed using a plating apparatus with the configuration shown in Figure 6, and a plating solution containing a cobalt ion source, conductive salt, pH buffer and brightener. Cobalt sulfate was used as the cobalt ion source, sodium chloride as the conductive salt and boric acid as the pH buffer. Prior to plating, the substrate was pretreated with an acidic degreasing solution at room temperature to 40°C for 30 seconds to 2 minutes. After pretreatment, the substrate was washed with water and plated under the following conditions, and finally washed with water again to form a Co film on the substrate. The surface of the obtained Co film was a uniform mirror surface with no visible film irregularities. In addition, a finite magnetic field was confirmed near the Co film using a gauss meter, indicating that magnetization remained in the Co film. "Plating conditions" In this embodiment, a current density of 0.5 to 3 A / dm is applied between the anode made of a pure cobalt plate and the above-mentioned substrate to be plated. 2 Plating was performed by passing a current through the plate. A ring-shaped electrode 1 to 3 mm wide around the circumference of the substrate, which is conductive only on the surface, was placed in contact with the surface to be plated, and a voltage was applied between the anode and the surface to be plated. The liquid temperature was kept within the range of room temperature to 40°C. The pH of the plating solution was controlled within the range of 2 to 4.5. During plating, a magnetic field of approximately 900 Oe was applied at the center of the substrate to be plated using a permanent magnet. The plating solution was constantly circulated using a liquid circulation mechanism, with a circulation flow rate of 10 to 15 L / min. The squeegee rod of the stirring mechanism was reciprocated in parallel to the substrate near the surface of the substrate at a speed of 50 to 500 mm / sec.

[0096] A pair of temperature control stages, one set at 30°C and the other at 20°C, was contacted with the silicon substrate side and the Co film side of the silicon substrate on which the Co film was formed. The current and voltage were measured between electrodes 11A and 12A in Fig. 3 using a Keithley Source Meter 2450. As a result, as shown in Fig. 8, when the direction of the heat flow applied in the direction perpendicular to the surface of the Co film was reversed, the direction of the current and voltage were reversed, and it was found that a voltage was generated from the heat flow due to the anomalous Nernst effect. This result corresponds to the introduction of magnetization in the in-plane direction of the Co film by plating under a magnetic field, and indicates that the two processes of film formation and magnetization introduction were able to be performed in one process. The voltage dependence of the output P was as shown in Fig. 9. The open circuit voltage was 2mV, the short circuit current was 0.4μA, and the maximum output was 0.2nW. [Explanation of symbols]

[0097] 1... anomalous Nernst effect material, 11... first electrode, 12... second electrode, 20... magnetic field application means, 100... thermoelectric conversion module, 101... substrate, 102... insulating layer, 103... connection layer, 104... electrode layer, 105... film of metal material, 106... resist pattern, 201... plating tank, 202... permanent magnet, 203... anode, 204... cathode, 205... electrode, 206... liquid supply port, 207... liquid drain port, 208... stirring mechanism, 208a... squeegee rod, L... plating liquid

Claims

1. A method for producing an anomalous Nernst effect material, comprising forming a film of a metal material exhibiting the anomalous Nernst effect on a substrate by wet plating in a magnetic field.

2. The manufacturing method according to claim 1 , wherein the metal material is a magnetic material having a coercive force of 3 Oe or more and 10 kOe or less.

3. The method according to claim 2 , wherein the magnetic material has a Curie temperature of 100° C. or higher.

4. The method according to claim 1 , wherein the wet plating is electroplating.

5. The method according to claim 4 , further comprising forming an insulating layer, a connection layer and an electrode layer on the substrate in this order from the substrate side before forming the film of the metallic material.

6. The method according to claim 1 , wherein the thickness of the metal film is from 0.05 μm to 3000 μm.

7. A method for producing a thermoelectric conversion module, comprising the step of producing an anomalous Nernst effect material by the production method according to any one of claims 1 to 6.

8. A method for manufacturing a heat flow sensor, comprising the step of manufacturing a thermoelectric conversion module by the manufacturing method according to claim 7.

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