Gd-co-based metal powder, method for producing same, conductive molded article, and thermoelectric conversion element

Abstract

The present invention provides a technique suitable for manufacturing a thermoelectric conversion element with high productivity, which uses the abnormal Nernst effect and obtains a high Nernst coefficient in a zero magnetic field. The present invention relates to a metal powder having an intermetallic compound GdCo5 as a main component, the metal powder having a 50% cumulative particle diameter D50 of 1-150 [mu] m and a 90% cumulative particle diameter D90 of 250 [mu] m or less in a volume-based particle size distribution obtained by a laser diffraction scattering method. The metal powder can be obtained, for example, by pulverizing an alloy block mainly composed of an intermetallic compound GdCo5.

Description

TECHNICAL FIELD

[0001] The present application relates to a Gd-Co-based metal powder which can be used as a raw material for a thermoelectric conversion element, and a method for producing the same. In addition, the present application relates to an electrically conductive molded body of the Gd-Co-based metal powder and a thermoelectric conversion element using the above electrically conductive molded body. BACKGROUND

[0002] In recent years, research on thermoelectric conversion elements utilizing the anomalous Nernst effect has been conducted. The anomalous Nernst effect is a phenomenon in which, when a heat flow in a direction orthogonal to spontaneous magnetization is applied to a magnetic body, an electromotive force in a direction orthogonal to both the magnetization and the heat flow is generated. If the anomalous Nernst effect is utilized, a current can be extracted in a direction orthogonal to the heat flow, and thus, unlike the case of utilizing the Seebeck effect, an advantage of being able to construct a thin thermoelectric conversion device is obtained. As a substance which exhibits a large anomalous Nernst effect at ordinary temperatures, for example, a strong magnetic intermetallic compound Co2MnGa is known.

[0003] In Patent Literature 1, an example in which a Co2MnGa single crystal was produced by a pulling method (Czochralski method) and the anomalous Nernst coefficient was measured is described. The Nernst coefficient of the Co2MnGa single crystal at room temperature (300 K) reached a high value of about 6 μV / K in the case where the direction of application of a magnetic field was parallel to any one of the

[100] ,

[110] , and

[111] directions of the crystal (paragraph 0021, Figure 4 ).

[0004] In Patent Literature 2, an example in which an anomalous Nernst material film is used in a heat flow sensor in a composite sensor having a heat flow sensor and a temperature sensor is described. As the anomalous Nernst material, several substances are listed (paragraph 0026). As a film formation method of the anomalous Nernst material film, a sputtering method is shown (paragraph 0030).

[0005] As main uses of thermoelectric conversion elements, a thermoelectric power generation device and a heat flow sensor can be listed.

[0006] A thermoelectric conversion element for realizing a thermoelectric power generation device is preferably a block having a thickness of several millimeters or so. If a single crystal obtained by a pulling method is used, a block having the above-mentioned size can be produced. However, the single crystal production technique such as the pulling method is high in cost and low in productivity, and thus is not practical in industrial production of a raw material for a thermoelectric power generation device. On the other hand, it is difficult to apply a film formation technique such as a sputtering method to industrial production of a block raw material for a thermoelectric power generation device.

[0007] A thermoelectric conversion element for realizing a heat flow sensor is desired to be a small-sized element if it is considered to be assembled in a part of a minute circuit pattern. Such a practice of cutting out a small-sized element from a single crystal obtained by a pull-up method or the like in multiple is difficult to be industrialized in terms of cost. In addition, it is also difficult to directly form a small-sized element of a prescribed shape by a pull-up method. On the other hand, a small-sized element in conformity with a prescribed circuit pattern can be directly formed on an insulating substrate according to a film formation technique such as a sputtering method. However, such a film formation method has low productivity, and the manufacturing cost of the heat flow sensor is increased.

[0008] In Patent Literature 3, as a material capable of widely coping with various shapes A powder of Co2MnGa is disclosed as a raw material for manufacturing a thermoelectric conversion element of a small size. For an electrically conductive molded body using the powder, a high Nernst coefficient is obtained as with Co2MnGa of a single crystal.

[0009] On the other hand, in Patent Literature 4, it is described that a powder of Mn3Sn, which is a strong magnet, exhibits a coercive force of about 0.25 to 0.5 T and shows a thermoelectric conversion action in which an abnormal Nernst effect occurs even in a state where no magnetic field is applied (hereinafter, sometimes referred to as "zero magnetic field").

[0010] Prior Art Documents

[0011] Patent Literature

[0012] Patent Literature 1: International Publication No. 2019 / 009308

[0013] Patent Literature 2: Japanese Patent Application Publication No. 2020-153668

[0014] Patent Literature 3: Japanese Patent Application Publication No. 2023-2425

[0015] Patent Literature 4: Japanese Patent Application Publication No. 2021-145116 SUMMARY

[0016] PROBLEMS TO BE SOLVED BY THE INVENTION

[0017] At present, a substance exhibiting a high Nernst coefficient like Co2MnGa described above is known. However, Co2MnGa lacks a coercive force, and thus it is almost impossible to obtain a thermoelectric conversion action in which an abnormal Nernst effect occurs even in a state where no magnetic field is applied (zero magnetic field). It is assumed that a thermoelectric conversion element used in a sensor is disposed in a small space inside an electronic device, and it is actually difficult to mount the thermoelectric conversion element together with a strong magnet in a device. Therefore, it is desired to apply a substance exhibiting a thermoelectric conversion action even in a zero magnetic field to a thermoelectric conversion element.

[0018] On the other hand, if the Mn3Sn powder disclosed in Patent Document 4 is used, thermoelectric conversion can be achieved even with zero magnetic field. However, its Nernst coefficient is quite small compared to Co2MnGa, and cannot be considered sufficient to construct a practical thermoelectric conversion element. In addition, the coercivity of Mn3Sn powder is said to be around 0.25 to 0.5T (Patent Document 4). Even when exposed to interference such as magnetic fields generated by equipment, it is desirable to develop a substance exhibiting an anomalous Nernst effect with higher coercivity to provide reliable and stable high thermoelectric conversion performance.

[0019] The purpose of this invention is to provide a device with high coercivity, a high Nernst coefficient in zero magnetic field, and easy and wide applicability to various shapes. A new material for manufacturing thermoelectric conversion elements of various sizes. Furthermore, the aim is to provide thermoelectric conversion elements with high Nernst coefficients obtained using this material.

[0020] Methods for solving problems

[0021] To achieve the above objectives, the following invention is disclosed in this specification.

[0022] [1] The metal powder is a powder with intermetallic compound GdCo5 as the main component. In the particle size distribution based on volume diffraction and scattering method, the cumulative 50% particle size D50 is 1 to 150 μm and the cumulative 90% particle size D90 is less than 250 μm.

[0023] [2] The method for manufacturing metal powder according to [1] above includes: an alloy block manufacturing step of solidifying molten metal of Gd-Co alloy to obtain an alloy block with intermetallic compound GdCo5 as the main component; and a pulverizing step of obtaining powder by pulverizing the alloy block.

[0024] [3] Conductive molded body of powder with intermetallic compound GdCo5 as the main component.

[0025] [4] According to the conductive molded body described above [3], in the particle size distribution of the powder with intermetallic compound GdCo5 as the main component, the cumulative 50% particle size D50 is 1 to 150 μm and the cumulative 90% particle size D90 is less than 250 μm in the volume reference obtained by laser diffraction and scattering method.

[0026] [5] The conductive molded body described in [3] or [4] above is a sintered body of powder with intermetallic compound GdCo5 as the main component.

[0027] [6] The conductive molded body according to any one of [3] to [5] above, wherein it exhibits a Nernst coefficient of 0.2 μV / K or higher at a temperature of 300 K without the application of a magnetic field.

[0028] [7] A thermoelectric conversion element that uses a conductive molded body according to any one of [3] to [6] above.

[0029] The effects of the invention

[0030] According to the present invention, a thermoelectric conversion element exhibiting a high Nernst coefficient in zero magnetic field and excellent resistance to interference from external magnetic fields can be obtained. The material used for this thermoelectric conversion element is powder, therefore the technology of the present invention can be widely applied to various shapes. Components of this size. Furthermore, the technology of this invention is superior in terms of cost and productivity compared to technologies using single crystals and sputtering methods to obtain thin films. Attached Figure Description

[0031] Figure 1 SEM images of Gd-Co metal powders as products of hammer mill grinding.

[0032] Figure 2 Here are SEM images of Gd-Co metal powders that were milled as samples.

[0033] Figure 3 Here are SEM images of Gd-Co metal powders as products of planetary ball milling.

[0034] Figure 4 The graphs illustrate the particle size distribution curves of the Gd-Co metal powder obtained in Example 1, including the hammer mill pulverized product, the sample mill pulverized product, and the planetary ball mill pulverized product.

[0035] Figure 5 The image shows X-ray diffraction patterns of hammer mill pulverized, sample mill pulverized, and planetary ball mill pulverized samples of the Gd-Co metal powder obtained in Example 1.

[0036] Figure 6 The graph shows the magnetization curves of the Gd-Co metal powder obtained in Example 1, exemplified by hammer mill pulverized product, sample mill pulverized product, and planetary ball mill pulverized product.

[0037] Figure 7 This diagram schematically illustrates the installation positions of the terminals for electrical measurement, the probes for temperature measurement, and the directions of heat flow and magnetic field for the sample used in the Nernst effect measurement.

[0038] Figure 8A graph showing the Nernst coefficient of a conductive molded body of GdCo5 powder, which was used as a sample mill-ground product. Detailed Implementation

[0039] [Gd-Co based metal powder]

[0040] In this invention, Gd-Co based metal powder with the intermetallic compound GdCo5 as the main component is used as a suitable material for thermoelectric conversion elements. The intermetallic compound GdCo5 has a hexagonal crystal structure and exhibits strong contramagnetism at room temperature.

[0041] Within the compositional range where the Gd (gadolinium) and Co (cobalt) ratios are close to the stoichiometric composition of GdCo5, intermetallic compounds with a GdCo5-type crystal structure can exist stably as a single phase. It is considered that intermetallic compound phases with a GdCo5-type crystal structure and heterogeneous Gd-Co alloys are obtained at the periphery of this compositional range. Even in compositions slightly deviating from the stoichiometric composition of GdCo5, crystal phases with a GdCo5-type crystal structure (i.e., crystal structures in which diffraction peaks corresponding to the diffraction peaks of each crystal plane from the stoichiometric composition of GdCo5 are observed in X-ray diffraction patterns) are included in the term "intermetallic compound GdCo5" as used in this specification.

[0042] The term "powder with intermetallic compound GdCo5 as the main component" refers to a powder in which the relationship I1 < I0 holds true when the integrated intensity of the highest peak in the diffraction pattern of the GdCo5-type crystal structure is set as I0, and the integrated intensity of the highest peak in the diffraction pattern of the heterogeneous phase (a phase other than the GdCo5-type crystal structure) is set as I1. Specifically, if no heterogeneous phase is detected, I1 = 0, satisfying the aforementioned I1 < I0 relationship. In thermoelectric conversion elements using powder with intermetallic compound GdCo5 as the main component, even if a heterogeneous phase other than GdCo5 is present, thermoelectric conversion caused by the anomalous Nernst effect of the GdCo5 phase occurs. However, to achieve efficient thermoelectric conversion characteristics, it is preferable to have a small amount of heterogeneous phase that does not exhibit the anomalous Nernst effect. For example, more preferably, I1 < 0.5I0, and even more preferably, I1 < 0.3I0. As a particularly preferred powder, powders containing a single phase of GdCo5 in which no heterogeneous phase was detected can be listed.

[0043] The particle size distribution of the Gd-Co metal powder, based on a volumetric particle size distribution obtained using laser diffraction and scattering, has a cumulative 50% particle size D50 of 1 μm or more and 150 μm or less, and a cumulative 90% particle size D90 of 250 μm or less. If the cumulative 50% particle size D50 is too large, the average particle size increases, leading to a decrease in coercivity. If the cumulative 90% particle size D90 is too large, the proportion of coarse particles increases, also resulting in a decrease in coercivity. The optimal particle size distribution conditions vary depending on the application and the manufacturing process of the component; generally, the optimal conditions can be set within the above-mentioned particle size distribution range. From the viewpoint of ensuring coercivity, the cumulative 50% particle size D50 is preferably 70 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less. Furthermore, the cumulative 90% particle size D90 is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 60 μm or less.

[0044] As a method for manufacturing Gd-Co based metal powder, for example, a method can be used which includes: an alloy block manufacturing step of solidifying molten metal containing Gd and Co to obtain an alloy block with the intermetallic compound GdCo5 as the main component; and a pulverizing step of pulverizing the alloy block to obtain powder.

[0045] If necessary, a further grading process can be carried out, using sieves or the like, to classify the powder obtained in the above-mentioned pulverizing process.

[0046] For molten Gd-Co alloys, the alloy can be obtained by melting raw material metals, Gd and Co, weighed according to a specified composition, using methods such as plasma arc melting or heating them in a crucible. The molten metal is then solidified to obtain an alloy block with the intermetallic compound GdCo5 as the main component. Since the intermetallic compound GdCo5 is relatively brittle, the alloy block can be pulverized into powder using mechanical means. For example, known pulverizing methods such as hammer mills, sample mills, and planetary ball mills can be used to adjust the particle size to the desired level. Furthermore, to adjust the final particle size distribution, the powder obtained by pulverization can be classified using sieves.

[0047] The Gd-Co metal powder of the present invention can be used as a material for thermoelectric conversion elements.

[0048] [Conductive Molded Body]

[0049] In this specification, an object in which powder is used in a material and molded into a specified shape, that is, an object that has the shape retention property under the use environment, is referred to as a "molded body of powder". In particular, a molded body of conductive powder is referred to as a "conductive molded body of powder". A conductive molded body of powder with the above-mentioned Gd-Co based metal powder as the main component, which uses the intermetallic compound GdCo5 as the main component, can be used as a thermoelectric conversion element.

[0050] Representative forms of conductive molded bodies from powder include pressed powder and sintered bodies. Even pressed powder can be used as thermoelectric conversion elements by maintaining its shape when assembled into a device in the operating environment. To ensure stable shape retention, sintered bodies are preferred.

[0051] Other forms of conductive molded powders besides pressed powders and sintered bodies include, for example, molded bodies in which powder is solidified into a specified shape using a binder such as a resin. When using a non-conductive binder, the powder particles must be in contact with each other to solidify. When using a conductive binder, contact between the powder particles is not required.

[0052] As a conductive molded body with GdCo5 as the main component of an intermetallic compound, when a sintered body is used, a sintered body with GdCo5 as the main component of an intermetallic compound can be manufactured using known sintering methods. When using a circuit pattern formed on an insulating substrate as part or all of the conductive molded body with GdCo5 as the main component of an intermetallic compound, a method can be used, such as forming a coating film of the circuit pattern on the insulating substrate using a coating material with the powder as a filler, and then sintering the coating film.

[0053] By using Gd-Co metal powder with the particle size distribution adjusted to the above, it is possible to construct conductive molded bodies with high coercivity and excellent thermoelectric conversion performance in a zero magnetic field environment at room temperature.

[0054] Example

[0055] [Example 1]

[0056] (Making of alloy blocks)

[0057] Metals Gd (manufactured by Nippon Yttrium Corporation, purity 3N) and Co (manufactured by Reamer Corp., purity 3N) were weighed as raw materials so that the atomic ratio was Ga:Co = 1.0:5.0. Molten metal of Ga-Co alloy was generated in an electric arc melting furnace (manufactured by Nisshin Giken Co., Ltd.) under an argon atmosphere. The molten metal was then solidified on a water-cooled copper plate to obtain an alloy block of about 50g.

[0058] (Powder production)

[0059] The obtained alloy block was coarsely ground in a mortar and pestle within a glove box under a nitrogen atmosphere. The powder from this stage is referred to as "coarse powder." Using this coarse powder, the following three types of powder were produced.

[0060] (i) Hammer mill pulverized products

[0061] The coarsely ground product was pulverized in the aforementioned glove box using a hammer mill (manufactured by Sansho Kogyo Co., Ltd., Hammer Crusher NH-34S, sieve: 0.3mm) to obtain the hammer mill pulverized product.

[0062] exist Figure 1 The image shows an SEM (scanning electron microscope) image of a product pulverized by a hammer mill. The SEM used was a FE-SEM JSM-7200F manufactured by Nippon Electron Ltd. (the same applies to the pulverized products shown below).

[0063] Elemental analysis of the hammer mill pulverized samples was performed using an EDX (Energy Dispersive X-ray Analysis) system (Oxford Instruments, X-Max20) attached to the SEM (the same was true for the following pulverized samples). The results showed that the composition of the hammer mill pulverized samples, expressed in atomic ratios, was Ga:Co = 1.2:5.0, with an oxygen content of 1.0% by mass.

[0064] In addition, the particle size distribution of hammer mill pulverized materials was measured using a dry laser diffraction particle size distribution measuring device (manufactured by Nippon Laser Co., Ltd., HELOS & RODOS) with a lens having a focal length of 200 mm (the same method was used for each of the following pulverized materials). The results showed that the cumulative 10% particle size D10 of the hammer mill pulverized materials, obtained using laser diffraction-scattering method, was 5 μm, the cumulative 50% particle size D50 was 44 μm, and the cumulative 90% particle size D90 was 111 μm.

[0065] (ii) Samples pulverized by a mill

[0066] A portion of the hammer mill pulverized product was pulverized in the glove box using a sample mill (manufactured by Kyoritsu Riko Co., Ltd., SK-M10 model) to obtain the sample mill pulverized product.

[0067] exist Figure 2 The image shows an SEM photograph of a sample milled into powder.

[0068] The composition of the milled sample obtained by EDX analysis, expressed as atomic ratios, is Ga:Co = 1.1:5.0, with an oxygen content of 1.0% by mass. Furthermore, the cumulative 10% particle size D10 of the milled sample, obtained by laser diffraction-scattering method, is 2 μm, the cumulative 50% particle size D50 is 13 μm, and the cumulative 90% particle size D90 is 44 μm.

[0069] (iii) Powdered by planetary ball mill

[0070] A portion of the hammer mill pulverized product was pulverized using a planetary ball mill (FRITZ GmbH, P-7) placed in a sealed container under a nitrogen atmosphere, resulting in a planetary ball mill pulverized product.

[0071] exist Figure 3 The image shows a SEM photograph of a product pulverized by a planetary ball mill.

[0072] The composition of the planetary ball mill pulverized material, determined by EDX, expressed in atomic ratios, is Ga:Co = 1.1:5.0, with an oxygen content of 1.3% by mass. Furthermore, the cumulative 10% particle size D10 of the planetary ball mill pulverized material, measured using laser diffraction-scattering (DDS) on a volume basis, is 3 μm, the cumulative 50% particle size D50 is 10 μm, and the cumulative 90% particle size D90 is 40 μm.

[0073] exist Figure 4 The particle size distribution curves of the hammer mill pulverized material, the sample mill pulverized material, and the planetary ball mill pulverized material are shown in the figure.

[0074] (Determination of X-ray diffraction patterns)

[0075] For the powders pulverized by the hammer mill, sample mill, and planetary ball mill, X-ray diffraction patterns were measured using an X-ray diffraction apparatus (Rigaku, Ultima IV) under the conditions of Cu-Kα rays, tube voltage 40 kV, tube current 40 mA, measurement step 0.02 degrees, and scanning speed 2 degrees / min.

[0076] exist Figure 5 The X-ray diffraction pattern is shown in the figure. It was confirmed that all the pulverized samples were powders formed from a roughly single-phase GaCo5 crystal phase, exhibiting diffraction patterns as hexagonal GaCo5 crystals.

[0077] (Determination of magnetic properties of powder)

[0078] The magnetic properties of the powder samples from the hammer mill, sample mill, and planetary ball mill were measured at room temperature using a VSM (Model-5, manufactured by Toei Kogyo Co., Ltd.). The measurement conditions were set to a maximum applied magnetic field of 6 T and a scanning speed of 1 min / FS. The results showed that all powder samples were not magnetized to saturation in a 6 T magnetic field. The hammer mill powder sample had a magnetization of 20.0 A at 6 T. m 2 / kg, the sample mill-ground product was 21.3A m 2 / kg, the product pulverized by the planetary ball mill is 21.3A. m 2 / kg. In addition, in terms of coercivity, the hammer mill crushed product is 0.74T (589kA / m), the sample mill crushed product is 1.48T (1178kA / m), and the planetary ball mill crushed product is 1.86T (1480kA / m).

[0079] exist Figure 6 The magnetization curves of the hammer mill pulverized material, the sample mill pulverized material, and the planetary ball mill pulverized material are shown in the figure.

[0080] (Fabrication of conductive molded bodies)

[0081] As conductive molding bodies of powder, sintered bodies were prepared using powders pulverized by a hammer mill, a sample mill, and a planetary ball mill, as described above. Approximately 5g of each pulverized powder was placed inside a cylindrical graphite battery with an inner diameter of 10mm. Using an upper and lower piston, the powder was heated in a discharge plasma sintering device under a pressure of 90MPa (7.065kN) and a vacuum atmosphere of approximately 1Pa, resulting in a cylindrical sintered body with a diameter of 10mm and a height of approximately 8mm. The heating mode was set to heat to 500℃, hold at 500℃ for 10 minutes, and then cool.

[0082] (Determination of the anomalous Nernst effect)

[0083] A cuboid sample with a length (L1) of approximately 8.0 mm, a width (W) of approximately 1.5 mm, and a thickness (H) of approximately 0.5 mm was cut from the aforementioned conductive molded body (sintered body). Figure 7 The diagram schematically illustrates the terminals for measuring electromotive force, the mounting positions of the probes for measuring temperature, and the directions of heat flow and magnetic field application. Terminals 2a and 2b for measuring electromotive force are mounted at the center of opposite sides of sample 1 for measuring the Nernst effect using conductive epoxy adhesive, allowing the voltage (V) generated between the two terminals to be measured using a voltmeter. This voltage, generated using the anomalous Nernst effect, is denoted as V. ANEA 5.0 mm gap (L2) was left at two locations on the top of sample 1 (indicated by reference numerals 31 and 32 in the attached figure). A temperature measuring probe was installed with a conductive epoxy adhesive to monitor the temperature difference ΔT between the probes. A physical property measurement system (PPMS) manufactured by Quantum Design was used to generate heat flow in the longitudinal direction of the sample and apply a magnetic field in the thickness direction of the sample. The electromotive force generated between the two ends in the width direction of the sample was measured at room temperature (300 K). Figure 7 The black arrows (labeled 4 in the figure) indicate the direction of heat flow in the sample. After the temperatures T1 and T2 stabilized, a magnetic field was applied to the sample, and the voltage V was measured. ANE (V). Figure 7 The white arrows (labeled 5 in the figure) indicate the direction of the magnetic field. The magnetic field is scanned between 3T and -3T, and between -3T and 3T.

[0084] The Nernst coefficient S was obtained using the following equation (1). ANE (μV / K).

[0085] S ANE (μV / K) = V ANE (V) / W / ΔT(K) / L2…(1)

[0086] in,

[0087] V ANE : Electromotive force (V) generated at both ends of the sample width direction.

[0088] W: Length of the sample in the width direction (mm)

[0089] ΔT: Temperature difference (K) at temperature probe installation location 2.

[0090] L2: The longitudinal distance (mm) of the sample at the temperature probe installation position at point 2.

[0091] The results are shown in Table 1. Figure 8 The example shows the measurement results of the Nernst coefficient for a conductive molded body pulverized using a sample mill. In this example, the Nernst coefficient at a temperature of 300 K and in a state without an applied magnetic field (zero magnetic field) is 0.4 μV / K.

[0092] The conductive molded body of the powder with intermetallic compound GdCo5 as the main component according to the present invention was confirmed to have a coercivity of more than 0.5T in the determination of Nernst coefficient and to exhibit an anomalous Nernst effect under zero magnetic field.

[0093] [Table 1]

[0094]

[0095] Explanation of reference numerals in the attached figures

[0096] 1. Samples for Nernst effect determination

[0097] 2a, 2b Electromotive Force Measurement Terminals

[0098] Temperature measurement locations 31 and 32

[0099] 4. Direction of heat flow in the sample

[0100] 5. Direction of the magnetic field

Claims

1. Metal powder, which is a powder with intermetallic compound GdCo5 as the main component, has a cumulative 50% particle size D50 of 1 to 150 μm and a cumulative 90% particle size D90 of less than 250 μm in the volume-based particle size distribution obtained by laser diffraction and scattering method.

2. The method for manufacturing metal powder according to claim 1, comprising: an alloy block manufacturing step of solidifying molten metal of a Gd-Co alloy to obtain an alloy block with the intermetallic compound GdCo5 as the main component; and a pulverizing step of pulverizing the alloy block to obtain powder.

3. A conductive molded body of powder, wherein the powder is mainly composed of the intermetallic compound GdCo5.

4. The conductive molded body according to claim 3, wherein, The powder with intermetallic compound GdCo5 as the main component has a cumulative 50% particle size D50 of 1 to 150 μm and a cumulative 90% particle size D90 of less than 250 μm in the volume-based particle size distribution obtained by laser diffraction and scattering method.

5. The conductive molded body according to claim 3 is a sintered body of powder with intermetallic compound GdCo5 as the main component.

6. The conductive molded body according to claim 3, wherein, It exhibits a Nernst coefficient of over 0.2 μV / K at a temperature of 300 K without the application of a magnetic field.

7. A thermoelectric conversion element, which uses a conductive molded body according to any one of claims 3 to 6.

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