Method for producing granulated substance, method for producing magnetic body, granulated substance, and magnetic body

Abstract

Provided is a method for producing a granulated substance (100) including a plurality of flat-shaped magnetic nanoparticles (30) in which, as a single body, a major axis and a minor axis shorter than the major axis intersect with each other and a flat surface along the major axis is wider than a side surface along the minor axis. The plurality of magnetic nanoparticles are mixed with a solvent (111) to generate a liquid first intermediate product (110). The plurality of magnetic nanoparticles contained in the liquid first intermediate product are dispersed. An external magnetic field having a gradient is applied to the dispersed first intermediate product to generate a second intermediate product (120) in which the plurality of magnetic nanoparticles are magnetically oriented. The liquid second intermediate product is solidified. The second intermediate product in a solidified state is granulated to generate a granulated substance including a plurality of the magnetically oriented magnetic nanoparticles.

Description

Method for manufacturing granules, method for manufacturing magnetic materials, granules, and magnetic materials Cross-reference of related applications

[0001] This application is based on Japanese Patent Application No. 2024-184996, filed in Japan on October 21, 2024, and incorporates the contents of the basic application by reference in whole.

[0002] The disclosures described herein relate to methods for producing granules, methods for producing magnetic materials, granules, and magnetic materials.

[0003] Patent Document 1 discloses a method for producing a composite magnetic material comprising a nanoparticle aggregate containing magnetic metal nanoparticles containing a magnetic metal and an intervening phase containing a non-magnetic metal.

[0004] Patent No. 6230513

[0005] Patent Document 1 describes that it is preferable for magnetic metal nanoparticles to form a nanoparticle texture in which they are in contact at points or on a surface, and that this nanoparticle texture is mainly oriented in one direction within the particle aggregate.

[0006] Patent Document 1 describes coating and drying in a magnetic field as means of orientation. However, it does not provide any further specific details. It is unclear whether nano-sized magnetic metal nanoparticles can be effectively oriented using these methods.

[0007] Magnetic metal nanoparticles have a large surface area relative to their volume, compared to, for example, microparticles. Therefore, even if a torque is generated in the magnetic metal nanoparticles by applying an external magnetic field to orient them, it is difficult for this torque to overcome the resistance that arises between the magnetic metal nanoparticles and the intervening phase, and between the magnetic metal nanoparticles themselves.

[0008] For the torque generated in magnetic metal nanoparticles to overcome resistance, the magnetic force of the external magnetic field needs to be increased. However, if such a strong external magnetic field is required, it becomes impossible to mass-produce oriented nanoparticle aggregates. This makes it impossible to mass-produce composite magnetic materials containing oriented nanoparticle aggregates. In other words, there is a problem in that it is impossible to mass-produce magnetic materials containing oriented magnetic metal nanoparticles.

[0009] This disclosure aims to provide a method for mass-producible granules containing magnetic nanoparticles, a method for producing a magnetic material, granules, and a magnetic material.

[0010] A method for producing granules according to the disclosed embodiment involves preparing a plurality of flattened magnetic nanoparticles in which a long axis intersects with a short axis shorter than the long axis, and the flattened plane along the long axis is wider than the side surface along the short axis; mixing the plurality of magnetic nanoparticles in a solvent to produce a liquid first intermediate product; dispersing the plurality of magnetic nanoparticles contained in the liquid first intermediate product; applying a gradient external magnetic field to the liquid first intermediate product containing the dispersed plurality of magnetic nanoparticles to produce a liquid second intermediate product in which the plurality of magnetic nanoparticles are magnetically oriented; solidifying the liquid second intermediate product; and granulating the solidified second intermediate product to produce granules comprising the plurality of magnetically oriented magnetic nanoparticles.

[0011] A method for manufacturing a magnetic material according to the disclosed embodiment involves preparing a plurality of flattened magnetic nanoparticles in which a major axis intersects with a minor axis shorter than the major axis, and the flattened plane along the major axis is wider than the side surface along the minor axis; mixing the plurality of magnetic nanoparticles in a solvent to produce a liquid first intermediate product; dispersing the plurality of magnetic nanoparticles contained in the liquid first intermediate product; applying a gradient external magnetic field to the liquid first intermediate product containing the dispersed plurality of magnetic nanoparticles to produce a liquid second intermediate product in which the plurality of magnetic nanoparticles are magnetically oriented; solidifying the liquid second intermediate product; granulating the solidified second intermediate product to produce granules comprising the plurality of magnetically oriented magnetic nanoparticles; and molding the plurality of granules while applying a second external magnetic field to produce a magnetic material in which the plurality of granules are magnetically oriented.

[0012] The granules of the disclosed embodiment comprise a plurality of flattened magnetic nanoparticles, each having a long axis and a short axis shorter than the long axis intersecting, with the flattened surface along the long axis being wider than the side surface along the short axis, and the plurality of magnetic nanoparticles are oriented.

[0013] The disclosed embodiment of the magnetic material comprises multiple granules, each containing multiple flattened magnetic nanoparticles, the nanoparticles having a long axis and a short axis shorter than the long axis intersecting, and the flattened surface along the long axis being wider than the side surface along the short axis. In the granules, the multiple magnetic nanoparticles are oriented, and the multiple granules are oriented.

[0014] According to this, the surface area of ​​the granules is smaller relative to the volume of the magnetic nanoparticles. Therefore, even without applying a strong magnetic field from the outside, the torque generated in the granules by an externally applied magnetic field tends to be greater than the resistance generated in the granules when they are oriented by the torque. As a result, it becomes easier to manufacture magnetic materials in which multiple granules are orienting. In other words, it becomes easier to manufacture magnetic materials in which multiple magnetic nanoparticles are orienting. This makes it easier to mass-produce such magnetic materials.

[0015] Furthermore, the manufacturing method involves dispersing multiple magnetic nanoparticles in a solvent. Therefore, even without applying a strong external magnetic field, the torque generated in the magnetic nanoparticles by an externally applied magnetic field tends to be greater than the resistance generated in the magnetic nanoparticles when they are oriented by the torque. As a result, it becomes easier to manufacture granules in which multiple magnetic nanoparticles are oriented, and thus easier to mass-produce such granules.

[0016] The reference numbers in parentheses above merely indicate the correspondence with the configurations described in the embodiments below, and do not limit the technical scope in any way.

[0017] This is a perspective view of a magnet. This is an enlarged view of region A enclosed by the dashed line in Figure 1. This is a perspective view showing a single magnetic nanoparticle. This is a cross-sectional view of a single magnetic nanoparticle. This is a schematic diagram showing the unit cell of an FeNi ordered alloy. This is a schematic diagram showing the unit cell of FeNiN. This is a flowchart for manufacturing an FeNi ordered alloy. This is a flowchart for manufacturing granules. This is a schematic diagram illustrating the manufacturing method shown in Figure 8. This is an SEM image showing the second intermediate product. This is an enlarged view of region B enclosed by the dashed line in Figure 10. This is an enlarged view of region C enclosed by the dashed line in Figure 11. This is a flowchart for manufacturing a magnetic material. This is a schematic diagram illustrating the manufacturing method shown in Figure 13. This is a schematic diagram showing the torque and resistance generated in a single magnetic nanoparticle. This is a schematic diagram showing the torque and resistance generated in granules. This is a graph showing the hysteresis curve of the second intermediate product.

[0018] This description will explain embodiments for implementing this disclosure with reference to the drawings. In later embodiments, parts corresponding to those described in earlier embodiments may be given the same reference numerals, and redundant explanations may be omitted. If only a part of the configuration is described in each embodiment, the description of the earlier embodiment may be applied to the other parts of the configuration.

[0019] It is possible to combine parts that are explicitly shown to be combinable in each form. In particular, if there are no problems with the combination, it is also possible to partially combine multiple forms with each other, a form with a modified form, and multiple modified forms with each other, even if it is not explicitly shown that they can be combined.

[0020] Furthermore, in the following, the three directions that are orthogonal to each other will be referred to as the X direction, Y direction, and Z direction. The X, Y, and Z directions are linear directions. In the drawings, the term "direction" is omitted, and they are simply shown as X, Y, and Z.

[0021] <First Embodiment> <Magnet> Figure 1 shows a magnet 10. The magnet 10 of this embodiment has six faces. Two of the six faces are aligned in the X direction, two of the remaining four faces are aligned in the Y direction, and the last two faces are aligned in the Z direction. The magnet 10 has a rectangular parallelepiped shape.

[0022] Of course, the shape of the magnet 10 is not particularly limited. For example, the magnet 10 may be arc-shaped. The shape of the magnet 10 can be changed as appropriate depending on the application. The magnet 10 corresponds to a magnetic material.

[0023] <Magnetic Section> Figure 2 shows a magnified view of the inside of the magnet 10. A part of the magnet 10 shown in this magnified view is referred to as the magnetic section 20. The magnetic section 20 contains magnetic nanoparticles 30 and molding resin 40. In Figure 2, multiple magnetic nanoparticles 30 are clearly separated by lines and shown individually.

[0024] <Single Unit> The term "single unit" above refers to a state in which particles are primary particles that are not aggregated or fixed to each other, and exist independently without being supported by a substrate or other support. The magnetic part 20 includes at least one of the single magnetic nanoparticles 30 themselves, powder as an aggregate of single magnetic nanoparticles 30, granular form of the powder, and a molded mass of the powder. The magnetic part 20 also includes granules 100, which are made up of multiple magnetic nanoparticles 30 in a single mass, as described later. The magnetic part 20 also corresponds to a magnetic material.

[0025] <Magnetic Nanoparticles> As shown in Figures 3 and 4, the magnetic nanoparticles 30 are individually flattened. The magnetic nanoparticles 30 have a flattened surface 30a and a side surface 30b. The two flattened surfaces 30a are spaced apart and side by side. The side surface 30b is located between the two flattened surfaces 30a. The side surface 30b extends around the direction in which the two flattened surfaces 30a are aligned, forming an annular shape. The side surface 30b connects the two flattened surfaces 30a.

[0026] The long axis 31 is aligned along the flattened surface 30a, and the short axis 32 is aligned along the side surface 30b. The long axis 31 and the short axis 32 intersect. The short axis 32 is aligned in the direction of the two flattened surfaces 30a. The length of the long axis 31 of the magnetic nanoparticle 30 is longer than the length of the short axis 32. The area of ​​the side surface 30b is smaller than that of the flattened surface 30a. Thus, the magnetic nanoparticle 30 is flattened in its own form. In the magnetic nanoparticle 30, the easy magnetization axis 33 is aligned along the flattened surface 30a.

[0027] In the following, for the sake of simplicity, the length of the major axis 31 will be referred to as the major axis length, and the length of the minor axis 32 will be referred to as the minor axis length. The major axis length refers to the longest length in the direction along the flattened plane 30a. The minor axis length refers to the longest length in the direction along the side surface 30b and intersecting the major axis 31.

[0028] As shown in Figure 4, the magnetic nanoparticles 30 have alloy particles 34 and an insulating coating 35. The surface of the alloy particles 34 is covered with the insulating coating 35.

[0029] As for the alloy particles 34, L1 ０ FeNi magnetic powder having a structure, ferrite magnetic powder, etc. can be used. The alloy particles 34 in this embodiment are L1 ０ It contains an FeNi ordered alloy with a type ordered structure. In addition to Fe and Ni, the alloy particles 34 may contain additives such as sulfur or unavoidable impurities. The alloy particles 34 determine the magnetic properties of the magnetic nanoparticles 30.

[0030] The alloy particles 34 form the shape of the magnetic nanoparticles 30. The alloy particles 34 are flattened in shape. The alloy particles 34 have two main surfaces 34a and an annular surface 34b connecting these two main surfaces 34a.

[0031] As its name suggests, the insulating coating 35 has insulating properties. The thickness of the insulating coating 35 is expected to be uniform. The thickness of the insulating coating 35 covering the main surface 34a is expected to be the same as the thickness of the insulating coating 35 covering the annular surface 34b.

[0032] The flattened surface 30a and side surface 30b of the magnetic nanoparticle 30 are formed by an insulating coating 35. However, the shape of the flattened surface 30a is determined by the main surface 34a of the alloy particle 34, and the shape of the side surface 30b is determined by the annular surface 34b of the alloy particle 34. The long axis 31 and the easy magnetization axis 33 are along the main surface 34a, and the short axis 32 intersects the long axis 31 and is along the annular surface 34b. If the magnetic nanoparticle 30 does not have an insulating coating 35, the main surface 34a of the alloy particle 34 corresponds to the flattened surface 30a, and the annular surface 34b corresponds to the side surface 30b.

[0033] The insulating film 35 functions to sever the magnetic coupling between alloy particles 34 included in a plurality of magnetic nanoparticles 30 that are located in the vicinity and adjacent to each other within the magnetic portion 20. The magnetic coupling between the plurality of alloy particles 34 refers to the exchange interaction, which is a quantum mechanical effect that occurs between particles of the same type. The insulating film 35 may also be referred to as a "magnetic severing layer" or a "magnetic severing coating layer".

[0034] <Unit cell> In FIG. 5, L1 ０ The unit cell of the FeNi regular alloy having the L1 type regular structure is shown as the FeNi superlattice 50. In the FeNi superlattice 50, based on the face-centered cubic lattice, Fe and Ni are arranged in layers in the (001) direction. The FeNi superlattice 50 has an I site 51 located at the end side and an II site 52 located in the middle in the stacking structure of the (001) plane of the face-centered cubic lattice. In FIG. 5, the locations where atoms are arranged at the I site 51 are indicated by white circles, and the locations where atoms are arranged at the II site 52 are indicated by black circles.

[0035] The a-axis 53 in such a crystal structure is in the (010) direction, and the c-axis 54 is in the (001) direction. The c-axis 54 is the easy magnetization axis 33. In the FeNi superlattice 50 with a regularity of 1.0 described later, only Ni atoms among Fe atoms and Ni atoms exist at the I site 51, and only Fe atoms among Fe atoms and Ni atoms exist at the II site 52.

[0036] The magnetic nanoparticles 30 are nanoparticles. The long axis length is 1000 nm or less, preferably several 100 nm or less. The short axis length is 100 nm or less, preferably several 10 nm or less. "nm" indicates "nanometer". <00The insulating film 35 functions to sever the magnetic coupling between alloy particles 34 included in a plurality of magnetic nanoparticles 30 that are located in the vicinity and adjacent to each other within the magnetic portion 20. The magnetic coupling between the plurality of alloy particles 34 refers to the exchange interaction, which is a quantum mechanical effect that occurs between particles of the same type. The insulating film 35 may also be referred to as a "magnetic severing layer" or a "magnetic severing coating layer".

[0037] When a plurality of magnetic nanoparticles 30 are included in the magnetic portion 20, it is presumed that not all of these plurality of magnetic nanoparticles 30 necessarily exist alone, and at least a part of them is in a state of being connected to each other. However, even in such a connected state, if there is no fundamental change in the flat shape and the L1 ０ type regular structure of the plurality of magnetic nanoparticles 30, it is presumed that the properties of the plurality of magnetic nanoparticles 30 will not become heterogeneous.

[0038] <Degree of regularity> In this embodiment, the magnetic part 20 is manufactured such that the degree of regularity measured by the powder X-ray diffraction method is more than 0.7, preferably 0.76 or more, and more preferably 0.8 or more. The "degree of regularity" is an index indicating the degree of regularization in the FeNi superlattice 50, as described in Patent No. 6528865 and the like.

[0039] The degree of regularity is evaluated based on the XRD pattern. Let J be the ratio of the integrated intensity of the superlattice diffraction peak to the integrated intensity of the basic diffraction peak in the measured X-ray diffraction pattern. Let K be the ratio of the integrated intensity of the superlattice diffraction peak to the integrated intensity of the basic diffraction peak in the FeNi regular alloy with a degree of regularity "1" estimated from the Rietveld simulation. Then, the degree of regularity is (J / K) ０．５ and is evaluated.

[0040] When the ratio of metal A present at the I-site 51 shown in FIG. 5 is x and the ratio of metal B present is 1 - x, the ratio of metal A and metal B present at the I-site 51 is A ｘ B １－ｘ and is represented as such. When the ratio of metal B present at the II-site 52 is x and the ratio of metal A present is 1 - x, the ratio of metal A and metal B present at the II-site 52 is A １－ｘ B ｘ and is represented as such. When the degree of regularity is OP, it is represented by OP = 2x - 1. x is a value between 0.5 and 1.0.

[0041] <FeNiN> There is FeNiN as a precursor material for the FeNi regular alloy. In FIG. 6, the unit cell of FeNiN is shown as the FeNiN lattice 60. The crystal structure including this unit cell can be identified from the XRD diffraction pattern. XRD is an abbreviation for X-ray diffraction.

[0042] The FeNiN lattice 60 has a III site 61, an IV site 62, and a V site 63. The III site 61 corresponds to the I site 51 in the FeNi superlattice 50. The IV site 62 corresponds to the II site 52 in the FeNi superlattice 50. The V site 63 is located midway between two adjacent III sites 61 in the stacking direction. In FeNiN 50, it is expected that Ni atoms are present at the III site 61, Fe atoms are present at the IV site 62, and N atoms are present at the V site 63.

[0043] <Method for Manufacturing Magnetic Materials> Next, the method for manufacturing magnetic nanoparticles 30 will be outlined based on Figure 7.

[0044] In step S10, FeNiN, a precursor material for FeNi ordered alloys, is synthesized. In newly synthesized FeNiN, many FeNiN particles are aggregated or stuck together.

[0045] In step S20, FeNiN is coarsely ground. This yields FeNiN particles that are smaller than FeNiN.

[0046] In step S30, a mechanical force, such as a mechanical shear force, is applied to the FeNiN particles. This flattens the shape of the FeNiN particles. At this point, the flattened FeNiN particles obtained have a particle size distribution.

[0047] In step S40, flattened FeNiN particles within a desired particle size range are selected from a plurality of flattened FeNiN particles with a particle size distribution. The flattened FeNiN particles are then classified.

[0048] In step S50, the surface of the classified, flattened FeNiN particles is coated with the constituent material of the insulating film 35. The constituent material of the insulating film 35 is silica, etc.

[0049] In step S60, the flattened FeNiN particles coated with the constituent material of the insulating film 35 are heat-treated (annealed). This repairs any defects that may have occurred in the flattened FeNiN particles due to previously performed processes such as coarse grinding and flattening.

[0050] In step S70, the heat-treated flattened FeNiN particles are subjected to a denitrification treatment. This removes nitrogen from the flattened FeNiN particles, thereby producing flattened magnetic nanoparticles 30.

[0051] Next, the method for producing the magnetic nanoparticles 30 shown in Figure 7 will be described in detail.

[0052] <FeNiN Synthesis> For the synthesis of FeNiN, a precursor material, techniques described in, for example, Japanese Patent Publication No. 6230513 and Japanese Patent Publication No. 6627818 can be used.

[0053] Specifically, FeNiN is synthesized by nitriding FeNi disorder alloy powder produced by methods such as thermal plasma, flame spray, or coprecipitation. FeNiN can also be obtained by reduction and nitriding of FeNi oxide. The FeNi oxide used in the reduction process may contain Fe oxide or Ni oxide, or an oxide containing both Fe and Ni.

[0054] The Fe oxide is not particularly limited, but for example, FeO, Fe ２ O ３ Fe ３ O ４ These include, among others. Fe oxides include oxides obtained by oxidizing raw materials such as metallic iron, iron hydroxide, iron carbonate, iron chloride, iron iodide, iron bromide, iron sulfate, iron nitrate, iron phosphate, and iron oxalate.

[0055] Ni oxides are not particularly limited, but examples include NiO. Ni oxides include oxides obtained by oxidizing raw materials such as metallic nickel, nickel hydroxide, nickel carbonate, nickel chloride, nickel iodide, nickel bromide, nickel sulfate, nickel nitrate, nickel phosphate, and nickel oxalate.

[0056] An oxide containing Fe and Ni can be produced by carrying out the following precipitation and oxidation steps. In the precipitation step, a solution containing Fe and Ni is mixed with a precipitating agent to obtain a precipitate containing Fe and Ni. Next, in the oxidation step, the precipitate is heat-treated to obtain an oxide containing Fe and Ni. According to the above production method, it is easy to control the average particle size and particle size distribution of the obtained oxide containing Fe and Ni, and the distribution of Fe and Ni in the oxide containing Fe and Ni tends to be uniform.

[0057] The Fe and Ni raw materials are not limited as long as they can be dissolved in an acidic solution. Examples of Fe raw materials include metallic iron, iron oxide, iron hydroxide, iron carbonate, iron chloride, iron iodide, iron sulfate, iron nitrate, iron phosphate, and iron oxalate. Examples of Ni raw materials include metallic nickel, nickel oxide, nickel hydroxide, nickel carbonate, nickel chloride, nickel iodide, nickel sulfate, nickel nitrate, nickel phosphate, and nickel oxalate. Examples of acidic solutions include sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid. The concentration of the solution containing Fe and Ni can be appropriately adjusted within the range in which the Fe and Ni raw materials are substantially soluble in the acidic solution.

[0058] To react a solution containing Fe and Ni with a precipitating agent, the precipitating agent may be added to the solution containing Fe and Ni, or the solution containing Fe and Ni may be added to the precipitating agent. The solution containing Fe and Ni referred to here only needs to be a solution containing Fe and Ni when reacting with the precipitating agent; the Fe and Ni raw materials may be prepared as separate solutions, and each solution may be added to react with the precipitating agent. Even when the Fe and Ni raw materials are prepared as separate solutions, the range can be adjusted as appropriate so that each raw material is substantially soluble in the acidic solution.

[0059] The precipitating agent mentioned above is not limited to any agent that reacts with a solution containing Fe and Ni to produce a precipitate. Examples of precipitating agents include alkaline solutions such as oxalic acid, sodium hydroxide aqueous solution, sodium bicarbonate aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution. Alternatively, a precipitate can be obtained by blowing carbon dioxide into a solution containing Fe and Ni. The precipitates produced may include oxalates, carbonates, and hydroxides.

[0060] To give a specific example, FeNiN can be obtained by firing iron nickel oxalate powder in air, hydrogen reduction, and nitriding.

[0061] <Coarse Grinding> For coarse grinding of FeNiN, general grinding methods such as ball milling can be used.

[0062] <Flattening> Flattening of FeNiN particles is not particularly limited, but can be achieved, for example, by applying mechanical shear force to the FeNiN particles. Specifically, a wet bead mill is performed on a slurry containing FeNiN particles. In this way, mechanical shear force is applied to the FeNiN particles, and their shape can be flattened.

[0063] The slurry containing the FeNiN particles described above can be prepared by dispersing coarsely ground FeNiN particles in a solvent containing a surfactant. A surfactant that provides good coating properties for the FeNiN particles can be used. Examples of surfactants include nitrogen-containing surfactants such as oleylamine and trioctylamine, and sulfur-containing surfactants such as octanthiol and triazinedithiol. Polymeric surfactants such as polyvinyl alcohol, polyacrylic acid, polyethyleneimine, and polyvinylpyrrolidone can also be used. As a solvent, a liquid that allows for stable dispersion of the surfactant-coated FeNiN particles can be used. Examples of solvents include pure water, alcohols such as ethanol and isopropyl alcohol, and nonpolar solvents such as toluene and cyclohexane.

[0064] As an example, a slurry containing 5% by weight of FeNiN particles in ethanol is introduced into a bead mill apparatus together with zirconia media with a diameter of 0.1 mm and processed at 600 rpm for 30 minutes. This process yields a slurry containing flattened FeNiN particles. The bead mill apparatus used is a planetary ball mill, PL-7, manufactured by Fritsch.

[0065] <Classification> The slurry containing flattened FeNiN particles is centrifuged. This allows for particle size classification. For example, centrifugation is performed in the following order: 500G for 10 min, 4000G for 10 min, and 4000G for 120 min. This allows the flattened FeNiN particles with larger particle sizes to settle first. These particles are then collected. To obtain high coercivity, the flattened FeNiN particles with smaller particle sizes are extracted. This coercivity is evaluated as the strength of the magnetic field when a magnetic field is applied to the magnetic nanoparticles 30 and the magnetization direction of the FeNi ordered alloy is switched by the influence of the magnetic field.

[0066] <Coating> As described above, the insulating film 35 plays a role in disrupting the magnetic bonds between multiple magnetic nanoparticles 30 located in close proximity within the magnetic portion 20. For this reason, the constituent material of the insulating film 35 must be a non-magnetic material. Furthermore, the constituent material of the insulating film 35 must be a substance that can be subjected to heat treatment and denitrification treatment, and that does not react with the alloy particles 34.

[0067] Examples of constituent materials for the insulating film 35 that satisfy the above requirements include oxides of Group III-VII and Group XIII-XVI elements, such as silica, titania, zirconia, yttria, and alumina. In addition, insulating materials such as nitride films can also be used as constituent materials for the insulating film 35. The thickness of the insulating film constituting the insulating film 35 is preferably 1 nm or more.

[0068] In this example, the classified flattened FeNiN particles were coated with silica (silica coating). When silica is used as the insulating film 35 in this way, the powdered flattened FeNiN particles are mixed with a solvent of water or ethanol to which tetraethoxysilane has been added, and then an aqueous ammonia solution is poured in. As a result, silica is produced by the hydrolysis and condensation of tetraethoxysilane. The flattened FeNiN particles are covered with silica. The flattened FeNiN particles are coated with the insulating film 35.

[0069] As explained above, the coating treatment on the flattened FeNiN particles is performed before the heat treatment and denitrification. This suppresses the sintering of the flattened FeNiN particles during the subsequent heat treatment and denitrification. In addition, it suppresses the bonding of the alloy particles 34 contained in the magnetic part 20 during the molding of the magnet 10. This suppresses the deterioration of the magnetic properties of the magnet 10.

[0070] <Heat Treatment> The heat treatment performed on the flattened FeNiN particles is carried out, for example, in an ammonia gas environment. Specifically, as an example, the flattened FeNiN particles are placed in an electric furnace capable of introducing ammonia gas. The ambient temperature is set to 300 to 450°C, and the treatment time is set to 4 to 48 hours. This arranges the atomic structure of the flattened FeNiN particles.

[0071] Flattened FeNiN particles contain sulfur as an impurity or additive. After grinding, the stabilizing effect of sulfur on the FeNiN particles weakens, making them more susceptible to decomposition at high temperatures. Therefore, the optimal heat treatment conditions vary depending on the amount of sulfur present in the flattened FeNiN particles and their particle size. The temperature for this heat treatment should preferably be lower than the nitriding temperature used in the FeNiN synthesis process.

[0072] <Denitrification> Flattened FeNiN particles, whose atomic arrangement has been aligned by heat treatment, are subjected to denitrification treatment. This denitrification treatment removes nitrogen from the flattened FeNiN particles. At the same time, the atomic arrangement is corrected. Flattened FeNi particles with a regular atomic arrangement and increased coercivity are produced. Alloy particles 34 containing an FeNi ordered alloy, covered with an insulating coating 35, are produced.

[0073] The denitrification treatment can be carried out using the apparatus and method described in Japanese Patent Publication No. 6230513 and Japanese Patent Publication No. 6627818. Specifically, the denitrification treatment can be carried out, for example, by heat treatment under a hydrogen atmosphere. The hydrogen flow rate can be, for example, 0.01 to 10 liters / min per 1 g of flattened FeNiN particles. Preferably, the hydrogen flow rate can be 0.1 to 5 liters / min. The heat treatment temperature can be, for example, 100 to 400°C. Preferably, the heat treatment temperature can be 200 to 350°C. The heat treatment time can be, for example, 1 to 24 hours. Preferably, the heat treatment time can be 2 to 10 hours.

[0074] <Long axis length and short axis length> The method for measuring the long axis length and short axis length of magnetic nanoparticles 30 is described below. The length can be measured using image analysis software.

[0075] The shapes of the multiple magnetic nanoparticles 30 visible in the image captured by the scanning electron microscope (SEM image) are varied. From these, magnetic nanoparticles 30 that make it easy to determine the longest length on the flattened plane 30a are selected. For example, particles whose flattened plane 30a has an elliptical shape, making it easy to determine the major axis length, are selected, while particles whose flattened plane 30a has a U-shape or J-shape, making it difficult to determine the major axis length, are not selected. For example, 100 such magnetic nanoparticles 30 are selected. Then, the longest length on the flattened plane 30a of these nanoparticles is measured, and the average value is calculated. In this way, the major axis length (average particle size) can be determined. The standard deviation of the measured values ​​for the major axis length of the 100 magnetic nanoparticles 30 can be evaluated as the measurement error of the major axis length.

[0076] From among several magnetic nanoparticles 30 with varying shapes displayed in the SEM image, a magnetic nanoparticle 30 is selected that makes it easy to determine the longest thickness between two flattened surfaces 30a on the side surface 30b. Similarly to the long axis length, for example, 100 magnetic nanoparticles 30 that make it easy to determine the longest thickness between two flattened surfaces 30a are selected. Then, the longest thickness on the side surface 30b of these nanoparticles is measured, and the average value is calculated. In this way, the short axis length can be determined. The standard deviation of the measured thicknesses of the 100 magnetic nanoparticles 30 can be evaluated as the thickness measurement error.

[0077] Of course, the number of magnetic nanoparticles 30 suitable for measuring the long axis length and short axis length is not particularly limited. For example, it is preferable to select at least 30 or more.

[0078] As described above, magnetic nanoparticles 30 suitable for measuring the long axis length and short axis length are selected. Therefore, the magnetic nanoparticles 30 used to measure the long axis length and the magnetic nanoparticles 30 used to measure the short axis length are different, meaning the objects of measurement for the long axis length and short axis length are different. However, as described above, 100 magnetic nanoparticles 30 are selected for each measurement of the long axis length and short axis length. The average values ​​of the long axis length and short axis length are calculated. Therefore, although the objects of measurement for the long axis length and short axis length are different, it is considered that the influence of the difference in measurement objects on the calculated long axis length and short axis length is small.

[0079] More precisely, when actually measuring the long axis length and short axis length as described above, it is better to measure the long axis length and short axis length of the flattened FeNiN particles before denitrification, rather than the long axis length and short axis length of the magnetic nanoparticles 30 after denitrification. The reason for this is as follows.

[0080] As shown in the manufacturing method in Figure 7, the coating treatment in step S50 is performed before the denitrification treatment in step S70. Therefore, in the magnetic nanoparticles 30 obtained by denitrification, the outer surface of the alloy particles 34 is covered with an insulating film 35. The insulating film 35 is electrically insulating. Therefore, it becomes difficult to obtain a clear SEM image due to charge-up. As a result, it becomes difficult to measure the long axis length and short axis length of the magnetic nanoparticles 30. For this reason, it is preferable to measure the long axis length and short axis length of the flattened FeNiN particles before they are covered with the insulating film 35, rather than the long axis length and short axis length of the magnetic nanoparticles 30.

[0081] Furthermore, it is presumed that the size of the alloy particles 34 of the magnetic nanoparticles 30 shrinks to some extent due to the denitrification treatment compared to the flattened FeNiN particles. It is presumed that the lattice constant decreases by about 10% due to the change from the FeNiN lattice 60 to the FeNi superlattice 50. However, this change in size is within the range of the measurement error (standard deviation) mentioned above. In addition, it is presumed that the particle shape and size distribution do not change much before and after denitrification. The thickness of the insulating coating 35 is about 1 nm, which is also within the range of measurement error. For these reasons, the major axis length and minor axis length based on the measurement results from the SEM image of the flattened FeNiN particles can be considered as the major axis length and minor axis length of the magnetic nanoparticles 30. In the magnetic nanoparticles 30 of Examples 1 to 3 described later, their major axis length and minor axis length are considered to be the major axis length and minor axis length based on the measurement results from the SEM image of the flattened FeNiN particles.

[0082] <Evaluation of Examples> In the classification process of step S40, magnetic nanoparticles 30 of Example 1 were produced by centrifugal separation under the conditions of 500 G and 10 min. In the classification process of step S40, magnetic nanoparticles 30 of Example 2 were produced by centrifugal separation under the conditions of 4000 G and 10 min. In the classification process of step S40, magnetic nanoparticles 30 of Example 3 were produced by centrifugal separation under the conditions of 4000 G and 120 min. It was confirmed that the shape of these magnetic nanoparticles 30 of Examples 1 to 3 was flattened.

[0083] In contrast, the nanoparticles of Comparative Example 1 were produced by omitting steps S30, S40, and S50 from the manufacturing method described in Figure 7. The shape of the nanoparticles of Comparative Example 1 was not flattened.

[0084] The major axis length and minor axis length of the magnetic nanoparticles 30 in the above-described examples, and the particle size of Comparative Example 1 were measured. Furthermore, their orderliness and coercivity were measured. Although Comparative Example 1 is not flattened, the method for measuring the major axis length and minor axis length of the magnetic nanoparticles 30 can be used to measure its length.

[0085] The measured length of the long axis of the magnetic nanoparticles 30 in Example 1 was 640 nm, with a measurement error (standard deviation) of 205 nm. The measured length of the short axis was 49 nm, with a measurement error of 15 nm. The degree of order was 0.80, with a measurement error of 0.04. The coercivity was 160 kA / m.

[0086] The measured length of the long axis of the magnetic nanoparticles 30 in Example 2 was 221 nm, with a measurement error of 82 nm. The measured length of the short axis was 33 nm, with a measurement error of 8 nm. The orderness was 0.81, with a measurement error of 0.04. The coercivity was 220 kA / m.

[0087] The measured length of the long axis of the magnetic nanoparticles 30 in Example 3 was 96 nm, with a measurement error of 40 nm. The measured length of the short axis was 20 nm, with a measurement error of 4 nm. The orderness was 0.89, with a measurement error of 0.05. The coercivity was 380 kA / m.

[0088] Furthermore, the particle size of the nanoparticles in Comparative Example 1 was 182 nm, with a measurement error of 64 nm. The orderliness was 0.63, with a measurement error of 0.03. The coercivity was 120 kA / m.

[0089] As shown above, the order of the nanoparticles in Comparative Example 1 could not exceed 0.7. In contrast, the order of the magnetic nanoparticles 30 in Examples 1 to 3 exceeded 0.7. The expected range of possible values ​​for the order of the nanoparticles is 0.76 or higher and 0.94 or lower. In Comparative Example 1, the coercivity was 120 kA / m, while in Examples 1 to 3, the coercivity was 160 to 380 kA / m.

[0090] Furthermore, the degree of regularity tended to increase as the minor axis length decreased. It is expected that a degree of regularity of 0.7 or higher can be achieved by setting the minor axis length to 100 nm or less, or to a few tens of nm or less. A possible range for minor axis lengths that yield a degree of regularity of 0.76 or higher is a few nanometers or more, and 50 nm or less.

[0091] Furthermore, the shorter the major axis length, the greater the coercivity tended to be. A range of major axis lengths that yield good coercivity is considered to be between several tens of nanometers and 350 nm.

[0092] As shown above, it was confirmed that Examples 1 to 3 showed improved regularity and greater coercivity compared to Comparative Example 1.

[0093] When diffraction spots were observed in flattened FeNiN particles using electron diffraction, diffraction spots indicating the presence of the c-axis 54 within the flattened plane were observed. Furthermore, it was found that some flattened FeNiN particles had a structure in which multiple regions with different c-axis orientations were arranged along the long axis. This orientation of the c-axis 54 is similar in the FeNi ordered alloy after denitrification.

[0094] Furthermore, a correlation was observed where the azimuthal distribution became smaller as the length of the major axis decreased. It is thought that as the length of the major axis decreased, the distribution in the c-axis direction narrowed, the degree of regularity increased, and the coercivity increased.

[0095] In Comparative Example 2, the nanoparticles produced by performing steps S30 and S40 of the manufacturing method described in Figure 7 after step S70 were flattened in shape. However, although the shape of Comparative Example 2 was flattened, the orderliness and coercivity were lower than those of Comparative Example 1.

[0096] Specifically, the measured length of the long axis of the nanoparticles in Comparative Example 2 was 245 nm, with a measurement error of 101 nm. The measured length of the short axis was 38 nm, with a measurement error of 8 nm. The orderness was 0.30, with a measurement error of 0.02. The coercivity was 25 kA / m.

[0097] Furthermore, analysis of the electron diffraction pattern of Comparative Example 2 revealed that while a diffraction pattern typical of polycrystalline particles was observed, no spots corresponding to {001} or {002}, which appear when the c-axis 54 is located within a flattened plane, were observed. Therefore, it was confirmed that Comparative Example 2 is polycrystalline and does not have a specific crystal orientation direction.

[0098] In the magnetic nanoparticle 30 described above, which has a flattened shape with a long axis 31 and a short axis 32, and in which the easy magnetization axis 33 is aligned with the flattened surface 30a along the long axis 31, the easy magnetization axis 33 is oriented inward towards the flattened surface 30a. As a result, it is less susceptible to the influence of the demagnetizing field, and it is possible to increase the coercivity.

[0099] <Granulated Material> As described above, the magnetic portion 20 contains magnetic nanoparticles 30 and molding resin 40. As shown in Figure 2, in the magnetic portion 20, multiple magnetic nanoparticles 30 are clustered together. Hereafter, this cluster of multiple magnetic nanoparticles 30 will be referred to as granulated material 100.

[0100] As described above, the multiple magnetic nanoparticles 30 are flattened. The flattened surfaces 30a of the multiple magnetic nanoparticles 30 contained in the granules 100 are aligned in the same direction. As a result, the easy magnetization axis of the granules 100 is fixed in one direction.

[0101] The easy magnetization axes of the multiple granules 100 contained in the magnet 10 are also aligned in one direction. Specifically, the easy magnetization axes of these multiple granules 100 are aligned in the Y direction. As a result, multiple magnetic nanoparticles 30 are oriented in the magnet 10.

[0102] <Method for manufacturing granules> First, in step S110 shown in Figure 8, magnetic nanoparticles 30 manufactured by the manufacturing method shown in Figure 7 are prepared. In this preparation stage, as shown in Figure 9, the magnetic nanoparticles 30 may be randomly aggregated or fixed together.

[0103] In step S120, the magnetic nanoparticles 30 are mixed with the solvent 111. This produces a first intermediate product 110. Specifically, the first intermediate product 110 contains 1.25% by weight of magnetic nanoparticles 30. The first mixture 110 may contain several times 1% by weight of magnetic nanoparticles 30. In this embodiment, in step S120, in order to facilitate the production of granules 100, a granulation resin 70 is mixed in addition to the solvent 111. The content of the granulation resin 70 is preferably 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of magnetic nanoparticles 30. From the viewpoint of shape retention and density improvement of the granules 100, the content of the granulation resin 70 is more preferably 2 parts by mass or more and 10 parts by mass or less. The method of mixing the magnetic nanoparticles 30, solvent 111, and granulation resin 70 is not particularly limited, and a ball mill or the like can be used.

[0104] The granulation resin 70 is shown enclosed by a dashed line in Figure 2. However, its illustration is omitted in Figures 9, 14, and 16. Whether multiple magnetic nanoparticles 30 are easily linked to each other or not depends on the type of magnetic nanoparticles 30 used. If multiple magnetic nanoparticles 30 can be linked to each other to produce granules 100, then this granulation resin 70 does not need to be used to produce the granules 100.

[0105] In step S130, a dispersion treatment is performed on the first intermediate product 110 to break the bonds of aggregated or stuck particles. For example, ultrasonic waves are generated in the first intermediate product 110. This generates bubbles within the first intermediate product 110. These bubbles break the bonds of aggregated or stuck particles, causing them to separate.

[0106] In this dispersion process, a dispersant that reduces the distribution density of the multiple magnetic nanoparticles 30 may be added to the first intermediate product 110. This dispersant can be determined according to the surface state of the magnetic nanoparticles 30. The dispersant can be determined according to the material of the insulating coating 35 that covers the surface of the alloy particles 34 contained in the magnetic nanoparticles 30.

[0107] Other dispersion methods exist. For example, the magnetic nanoparticles 30 can be mixed with a high-viscosity substance and mechanically stirred. The viscous force of the high-viscosity substance and the force of mechanical stirring can break the bonds of aggregated or stuck particles. Alternatively, a simpler method can be used, such as a jet mill, to break the bonds of aggregated or stuck particles. Such dispersion methods for breaking bonds are not particularly limited. Figure 9 illustrates a first intermediate product 110 containing a plurality of dispersed magnetic nanoparticles 30.

[0108] In step S140, a first external magnetic field with a spatial magnetic field gradient is applied to the first intermediate product 110, which contains magnetic nanoparticles 30 whose particle size has been reduced by the dispersion process. This first external magnetic field generates torque in the magnetic nanoparticles 30. The distribution density of magnetic nanoparticles 30 in the liquid first intermediate product 110 is sparse. As a result, the magnetic nanoparticles 30 are easily rotated due to the torque.

[0109] This rotation causes the easy magnetization axes 33 of the multiple magnetic nanoparticles 30 to align with the direction in which the first external magnetic field is applied. That is, the flattened surfaces 30a of the multiple magnetic nanoparticles 30 align with the direction of application. In addition, the multiple magnetic nanoparticles 30 move freely in the liquid first intermediate product 110 due to the gradient of the first external magnetic field. Multiple magnetic nanoparticles 30 whose easy magnetization axes 33 align with the direction in which the first external magnetic field is applied become densely packed together. These densely packed multiple magnetic nanoparticles 30 become connected to each other. This generates the second intermediate product 120.

[0110] Next, in step S150, the solvent 111 is removed from the second intermediate product 120. This extracts the second intermediate product 120 in a solid state. Methods for removing the solvent 111 include vaporization and filtration. This removal process corresponds to solidification. In this embodiment, the granulation resin 70 is solidified in step S150. The second intermediate product 120 shown in Figure 9 is in a solid state.

[0111] Figures 10 and 11 show SEM images of the second intermediate product 120 in a solid state. Figure 12 shows a TEM image of the second intermediate product 120 in a solid state. In the SEM images, the white areas represent the second intermediate product 120. In the TEM images, the black areas represent the magnetic nanoparticles 30, and the white areas represent other materials. The white areas represent, for example, voids and granulation resin 70.

[0112] The shape of the second intermediate product 120 shown in Figure 10 is determined by the gradient of the first external magnetic field applied in step S140. As shown in Figure 11, the magnetic nanoparticles 30 do not appear to be particularly unevenly distributed in the second intermediate product 120. However, as shown in Figure 12, when magnified to a size where each magnetic nanoparticle 30 is visible individually, it can be seen that multiple magnetic nanoparticles 30 have gathered together to form a single clump. It can be seen that the flattened surfaces 30a of the multiple magnetic nanoparticles 30 forming this clump are not completely random, but are aligned in one direction. It can be seen that many of the flattened surfaces 30a of the multiple magnetic nanoparticles 30 shown in Figure 12 tend to be aligned in the left-right direction of the paper.

[0113] Next, in step S160, the solid second intermediate product 120 is crushed and granulated. This produces the granulated product 100. The granulation method is not particularly limited, and granulation can be carried out using a planetary mill, jet mill, ball mill, roller mill, pin mill, bead mill, etc.

[0114] In step S170, an alternating magnetic field is applied to the granules 100. This reverses the magnetization of at least some of the multiple magnetic nanoparticles 30 contained in the granules 100. The magnetic energy of the multiple magnetic nanoparticles 30 contained in the granules 100 is stabilized. The granules 100 is demagnetized. This demagnetization process can also be performed by applying heat, for example. In this case, the temperature is about 300°C. The demagnetization process in step S170 is optional.

[0115] The size of the granules 100 produced by the process described above is approximately 100 nm or more and 1 mm or less. The preferred size of the granules 100 is approximately 300 nm or more and 100 μm or less.

[0116] <Method for Manufacturing Magnetic Material> First, in step S210 shown in Figure 13, the granules 100 produced by the manufacturing method shown in Figure 8 and the molding resin 40 are mixed. This generates a third intermediate product 130. In this case, the molding resin 40 may be in a molten state or in powder form. The third intermediate product 130 may be a solid or a liquid. In the molding process described later, the third intermediate product 130 may be a solid or a liquid.

[0117] Next, in step S220, a second external magnetic field is applied to the third intermediate product 130. This generates torque in the granules 100 contained in the third intermediate product 130.

[0118] The distribution density of granules 100 in the third intermediate product 130 is denser than the distribution density of magnetic nanoparticles 30 in the liquid first intermediate product 110, when the third intermediate product 130 does not contain a solvent. However, the surface area of ​​the granules 100 is smaller relative to its volume than that of the magnetic nanoparticles 30. Therefore, the torque generated in the granules 100 tends to be greater than the resistance generated in the granules 100 when they try to rotate due to that torque.

[0119] Figures 15 and 16 show a simplified relationship between torque and resistance in the magnetic nanoparticles 30 and the granules 100. As indicated by the size and thickness of the curved arrows, the first torque T1 generated in the magnetic nanoparticles 30 is only slightly greater than the first resistance R1 generated in the magnetic nanoparticles 30 when they attempt to rotate due to the first torque T1. In contrast, the second torque T2 generated in the granules 100 tends to be greater than the second resistance R2 generated in the granules 100 when they attempt to rotate due to the second torque T2. Therefore, under the same conditions, the granules 100 rotate more easily than the magnetic nanoparticles 30. The granules 100 are also more easily magnetically oriented than the magnetic nanoparticles 30.

[0120] Due to the torque-resistance relationship described above, when a second external magnetic field is applied to the third intermediate product 130, the multiple granules 100 contained therein become magnetically oriented. While oriented in this way, the third intermediate product 130 is molded and solidified. In this way, a magnet 10 is manufactured. The molding method is not particularly limited and can include methods such as hand pressing, rolling with a roller compactor, injection molding, and compression molding.

[0121] As mentioned above, the granules 100 are demagnetized in step S170. However, in step S220, a second external magnetic field is applied to the third intermediate product 130 containing the granules 100. This second external magnetic field is approximately 3T. By applying a magnetic field of this magnitude, the magnetization of the granules 100 is restored, and the orientation of the multiple granules 100 is achieved.

[0122] <Degree of Magnetic Orientation> Figure 17 shows the hysteresis curve of the second intermediate product 120 in a solid state. The maximum value of the external magnetic field is approximately 3T. The magnetic flux density output from the second intermediate product 120 when the external magnetic field is at its maximum value is the saturation magnetic flux density. In Figure 17, this saturation magnetic flux density is defined as 1. When the external magnetic field is gradually reduced to zero, the magnetic flux density output from the second intermediate product 120 corresponds to the residual magnetic flux density. If the granules 100 are magnetically oriented in a completely random manner, this residual magnetic flux density is expected to be 0.5. In contrast, in this implementation, the residual magnetic flux density is 0.75 or higher. Therefore, in this implementation, it was confirmed that the granules 100 are magnetically oriented in the second intermediate product 120. That is, it was confirmed that multiple magnetic nanoparticles 30 are magnetically oriented in the second intermediate product 120. Using the second intermediate product 120, a magnet 10 is manufactured according to the manufacturing method described above. As a result, it is expected that multiple magnetic nanoparticles 30 in the magnet 10 will be magnetically oriented.

[0123] <Effects> Flat-shaped magnetic nanoparticles 30 can be produced by the manufacturing method shown in Figure 7. Furthermore, granules 100 containing these magnetic nanoparticles 30 can be produced by the manufacturing method shown in Figure 9.

[0124] Because the granules 100 are used, it becomes easier to manufacture a magnet 10 in which multiple granules 100 are oriented, even if the magnetic force of the second external magnetic field is not large. In other words, it becomes easier to manufacture a magnet 10 in which multiple magnetic nanoparticles 30 are oriented. It becomes easier to mass-produce such magnets 10.

[0125] Furthermore, in step S130, multiple magnetic nanoparticles 30 contained in the first intermediate product 110 are dispersed. As a result, even if the magnetic force of the first external magnetic field is not large, the torque generated in the magnetic nanoparticles 30 tends to be greater than the resistance generated in the magnetic nanoparticles 30 when they are oriented by the torque. As a result, it becomes easier to manufacture granules 100 in which multiple magnetic nanoparticles 30 are oriented. This also makes it easier to mass-produce such granules 100.

[0126] Furthermore, permanent magnets, electromagnetic coils, etc., are used to generate external magnetic fields such as the first external magnetic field and the second external magnetic field. In this disclosure, it is not necessary to generate a large magnetic field, so an external magnetic field may be continuously generated using a permanent magnet, or an external magnetic field may be continuously generated by continuously flowing current through an electromagnetic coil without worrying about heat generation. This makes it easier to mass-produce the granules 100 and the magnets 10.

[0127] In contrast, when it becomes necessary to generate a large magnetic field, a large current must be passed through the electromagnetic coil. In this case, a new approach is required: suppressing the heat generated by the electromagnetic coil. To satisfy both the flow of a large current and the suppression of heat generation, for example, the charging and discharging of a capacitor can be repeated. By doing so, current flows intermittently through the electromagnetic coil, and an intermittent magnetic field is generated from the electromagnetic coil.

[0128] To reiterate, this disclosure does not require the use of such a strong and intermittent magnetic field. Therefore, the equipment for manufacturing the granules 100 and the magnets 10 can be simplified. The granules 100 and the magnets 10 can be easily mass-produced. Furthermore, damage to the magnets 10 and the magnetic nanoparticles 30 contained in the granules 100 due to a strong magnetic field is suppressed.

[0129] The magnet 10 is manufactured using demagnetized granules 100. Therefore, compared to using magnetized granules 100, it is easier to magnetically orient the granules 100 during the manufacturing of the magnet 10.

[0130] The alloy particles 34 contained in the magnetic nanoparticles 30 have an order degree of 0.76 to 0.94 and a coercivity of 160 to 380 kA / m, L1 ０ It contains an FeNi ordered alloy with a type ordered structure. The alloy particles 34 are contained in the magnet 10 and are also oriented. ０ FeNi ordered alloys with a type ordered structure possess high heat resistance properties.

[0131] Therefore, the magnet 10 containing the alloy particles 34 has high coercivity and high heat resistance. The magnetic properties of the magnet 10 are less likely to deteriorate due to the heat generated during, for example, two-color molding. In addition, a resin with a high melting point can be used as the constituent material of the molding resin 40. Specifically, the melting point of the resin can be 300°C or higher. Therefore, the magnet 10 is easy to apply.

[0132] <Variations> The disclosure of this specification is not limited to the exemplary embodiments. The disclosure includes the exemplary embodiments and modifications made by those skilled in the art based on those exemplary embodiments. The disclosure is not limited to combinations of parts and elements shown in the embodiments, but can be implemented in various modifications. The disclosure can be implemented in a variety of combinations. The disclosure may have parts that can be added to the embodiments. The disclosure includes embodiments in which parts and elements have been omitted. The disclosure includes substitutions of parts, substitutions of elements, combinations of parts, or combinations of elements between one embodiment and another. The technical scope of the disclosure is not limited to the descriptions of embodiments. The technical scope of the disclosure is indicated by the description of the claims. The technical scope of the disclosure should be understood to include the description of the claims and equivalents, and all modifications within the claims.

[0133] The applications of the granulated material 100 are not limited to the manufacture of magnets 10, but can also be applied to the manufacture of magnetic recording media, etc. Furthermore, the expression "orderliness measured by powder X-ray diffraction" does not necessarily mean that the orderliness is directly measured by powder X-ray diffraction, but includes the orderliness that can be calculated using various patterns, waveforms, values, etc., measured by powder X-ray diffraction. For this reason, "orderliness measured by powder X-ray diffraction" can also be rephrased as "orderliness obtained by measurement using powder X-ray diffraction."

[0134] In the embodiment, the granulating resin 70 can be either a thermoplastic resin or a thermosetting resin. Examples of thermoplastic resins include nylon, polyester, polyphenylene sulfide, and polyphenylene sulfide. Examples of thermosetting resins include epoxy resin and phenolic resin. In this embodiment, the granulating resin 70 is an epoxy resin.

[0135] The molding resin 40 can be either a thermoplastic resin or a thermosetting resin. The constituent materials of the molding resin 40 and the granulation resin 70 may be the same or different.

[0136] However, if both the granulation resin 70 and the molding resin 40 are thermoplastic resins, the melting point or glass transition temperature of the molding resin 40 is lower than that of the granulation resin 70. If the granulation resin 70 is a thermoplastic resin and the molding resin 40 is a thermosetting resin, the thermosetting temperature of the molding resin 40 is lower than that of the granulation resin 70. By satisfying these temperature relationships, the flow of the granulation resin 70 due to the heat of the molten molding resin 40 is suppressed. This suppresses changes in the shape of the granulated product 100.

[0137] In this embodiment, an example of manufacturing a granule 100 containing one type of magnetic nanoparticle 30 is shown. However, granules 100 containing multiple types of particles may be manufactured as long as their size is at the nanoscale. Furthermore, granules 100 containing different types of magnetic nanoparticles 30 may be manufactured, and magnets 10 may be manufactured using these different types of granules 100.

[0138] <Disclosure of Technical Ideas> This specification discloses several technical ideas as described in the following paragraphs. Some paragraphs may be written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs may be written in a multiple dependent form, where they refer to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical ideas.

[0139] <Technical Concept 1> A method for producing granules, comprising: preparing a plurality of flattened magnetic nanoparticles (30) in which a major axis (31) and a minor axis (32) shorter than the major axis intersect, and the flattened surface (30a) along the major axis is wider than the side surface (30b) along the minor axis; mixing the plurality of magnetic nanoparticles in a solvent (111) to produce a liquid first intermediate product (110); dispersing the plurality of magnetic nanoparticles contained in the liquid first intermediate product; applying a gradient external magnetic field to the liquid first intermediate product containing the dispersed plurality of magnetic nanoparticles to produce a liquid second intermediate product (120) in which the plurality of magnetic nanoparticles are magnetically oriented; solidifying the liquid second intermediate product; and granulating the solidified second intermediate product to produce a granule (100) comprising the plurality of magnetically oriented magnetic nanoparticles.

[0140] <Technical Concept 2> A method for manufacturing granules according to Technical Concept 1, wherein a plurality of magnetic nanoparticles contained in the granules are demagnetized by applying an alternating magnetic field to the granules.

[0141] <Technical Idea 3> A method for producing granules according to Technical Idea 1 or Technical Idea 2, comprising mixing a plurality of the magnetic nanoparticles with the solvent and a granulation resin (70) to produce a liquid first intermediate product.

[0142] <Technical Idea 4> A method for producing granules according to any one of Technical Ideas 1 to 3, wherein the solvent contained in the liquid second intermediate product is vaporized to solidify the second intermediate product.

[0143] <Technical Concept 5> Multiple flattened magnetic nanoparticles (30) are prepared, in which a long axis (31) and a short axis (32) shorter than the long axis intersect, and the flattened surface (30a) along the long axis is wider than the side surface (30b) along the short axis. Multiple magnetic nanoparticles are mixed in a solvent (111) to produce a liquid first intermediate product (110). Multiple magnetic nanoparticles contained in the liquid first intermediate product are dispersed. A gradient external magnetic field is applied to the liquid first intermediate product containing the dispersed multiple magnetic nanoparticles to produce a liquid second intermediate product (120) in which the multiple magnetic nanoparticles are magnetically oriented. The liquid second intermediate product is solidified. The solidified second intermediate product is granulated to produce a granule (100) comprising multiple magnetically oriented magnetic nanoparticles. A method for manufacturing a magnetic material, comprising molding a plurality of the granules while applying a second external magnetic field to them to generate a magnetic material (10) in which the plurality of granules are magnetically oriented.

[0144] <Technical Idea 6> A method for manufacturing a magnetic material according to technical idea 5, wherein an alternating magnetic field is applied to the granules to demagnetize a plurality of magnetic nanoparticles contained in the granules, and the magnetic material is produced by molding the demagnetized plurality of granules while applying the second external magnetic field.

[0145] <Technical Idea 7> A method for producing a magnetic material according to technical idea 5 or technical idea 6, wherein the magnetic material is produced by mixing a plurality of the granules with a molding resin (40) and then molding it while applying the second external magnetic field.

[0146] <Technical Concept 8> A granulated material comprising multiple flattened magnetic nanoparticles, each having a long axis (31) and a short axis (32) shorter than the long axis intersecting, and the flattened surface (30a) along the long axis being wider than the side surface (30b) along the short axis, wherein the multiple magnetic nanoparticles are oriented.

[0147] <Technical Concept 9> The magnetic nanoparticles are L1 ０ Includes a FeNi ordered alloy with a type ordered structure, the L1 ０The granulated material according to technical concept 8, wherein the easy magnetization axis (33) of the type ordered structure lies along the flattened plane, and the easy magnetization axes of the plurality of magnetic nanoparticles are aligned, thereby orienting the plurality of magnetic nanoparticles.

[0148] <Technical Idea 10> A granulated material according to Technical Idea 8 or Technical Idea 9, comprising a granulating resin (70) that connects a plurality of the magnetic nanoparticles.

[0149] <Technical Concept 11> A magnetic material having a plurality of granules (100) each having a plurality of flattened magnetic nanoparticles, each having a long axis (31) and a short axis (32) shorter than the long axis intersecting, and the flattened surface (30a) along the long axis being wider than the side surface (30b) along the short axis, wherein the plurality of magnetic nanoparticles in the granules are oriented, and the plurality of granules are oriented.

[0150] <Technical Concept 12> The magnetic nanoparticles are L1 ０ Includes a FeNi ordered alloy with a type ordered structure, the L1 ０ A magnetic material according to the technical concept 11, wherein the easy magnetization axis (33) of the type ordered structure lies along the flattened plane, and the easy magnetization axes of the plurality of magnetic nanoparticles are aligned, thereby orienting the plurality of magnetic nanoparticles.

[0151] <Technical Idea 13> The granulated material is a magnetic material according to technical idea 11 or technical idea 12, having a granulating resin (70) that connects a plurality of the magnetic nanoparticles.

[0152] <Technical Idea 14> A magnetic material according to any one of the technical ideas 11 to 13, having a molding resin (40) that connects a plurality of the granules.

Claims

1. A method for producing granules, comprising: preparing a plurality of flattened magnetic nanoparticles (30) in which a major axis (31) and a minor axis (32) shorter than the major axis intersect, and the flattened surface (30a) along the major axis is wider than the side surface (30b) along the minor axis; mixing the plurality of magnetic nanoparticles in a solvent (111) to produce a liquid first intermediate product (110); dispersing the plurality of magnetic nanoparticles contained in the liquid first intermediate product; applying a gradient external magnetic field to the liquid first intermediate product containing the dispersed plurality of magnetic nanoparticles to produce a liquid second intermediate product (120) in which the plurality of magnetic nanoparticles are magnetically oriented; solidifying the liquid second intermediate product; and granulating the solidified second intermediate product to produce a granule (100) comprising the plurality of magnetically oriented magnetic nanoparticles.

2. The method for producing granules according to claim 1, wherein a plurality of magnetic nanoparticles contained in the granules are demagnetized by applying an alternating magnetic field to the granules.

3. A method for producing granules according to claim 1 or 2, comprising mixing a plurality of magnetic nanoparticles with the solvent and granulation resin (70) to produce the liquid first intermediate product.

4. The method for producing granules according to claim 3, wherein the solvent contained in the liquid second intermediate product is vaporized to solidify the second intermediate product.

5. A method for producing a magnetic material, comprising: preparing a plurality of flattened magnetic nanoparticles (30) in which a major axis (31) and a minor axis (32) shorter than the major axis intersect, and the flattened surface (30a) along the major axis is wider than the side surface (30b) along the minor axis; mixing the plurality of magnetic nanoparticles in a solvent (111) to produce a liquid first intermediate product (110); dispersing the plurality of magnetic nanoparticles contained in the liquid first intermediate product; applying a gradient external magnetic field to the liquid first intermediate product containing the dispersed plurality of magnetic nanoparticles to produce a liquid second intermediate product (120) in which the plurality of magnetic nanoparticles are magnetically oriented; solidifying the liquid second intermediate product; granulating the solidified second intermediate product to produce granules (100) comprising the plurality of magnetically oriented magnetic nanoparticles; and molding the plurality of granules while applying a second external magnetic field to produce a magnetic material (10) in which the plurality of granules are magnetically oriented.

6. A method for producing a magnetic material according to claim 5, comprising applying an alternating magnetic field to the granules to demagnetize a plurality of magnetic nanoparticles contained in the granules, and forming the demagnetized plurality of granules while applying the second external magnetic field to produce the magnetic material.

7. A method for producing a magnetic material according to claim 5 or 6, wherein the magnetic material is produced by mixing a plurality of the granules with a molding resin (40) and then molding while applying the second external magnetic field.

8. A granulated material comprising a plurality of flattened magnetic nanoparticles, each having a long axis (31) and a short axis (32) shorter than the long axis intersecting, and the flattened surface (30a) along the long axis being wider than the side surface (30b) along the short axis, wherein the plurality of magnetic nanoparticles are oriented.

9. The magnetic nanoparticles are L1 ０ Includes a FeNi ordered alloy with a type ordered structure, the L1 ０ The granulated material according to claim 8, wherein the easy magnetization axis (33) of the type ordered structure is along the flattened plane, and the easy magnetization axes of the plurality of magnetic nanoparticles are aligned, thereby orienting the plurality of magnetic nanoparticles.

10. The granulated material according to claim 8 or claim 9, comprising a granulating resin (70) for linking a plurality of the magnetic nanoparticles.

11. A magnetic material having a plurality of granules (100) each having a plurality of flattened magnetic nanoparticles, each having a long axis (31) and a short axis (32) shorter than the long axis intersecting, and the flattened surface (30a) along the long axis being wider than the side surface (30b) along the short axis, wherein the plurality of magnetic nanoparticles in the granules are oriented, and the plurality of granules are oriented.

12. The magnetic nanoparticles are L1 ０ Includes a FeNi ordered alloy with a type ordered structure, the L1 ０ The magnetic material according to claim 11, wherein the easy magnetization axis (33) of the type ordered structure is along the flattened plane, and the easy magnetization axes of the plurality of magnetic nanoparticles are aligned, thereby orienting the plurality of magnetic nanoparticles.

13. The magnetic material according to claim 12, wherein the granulated material comprises a granulating resin (70) that connects a plurality of magnetic nanoparticles.

14. A magnetic material according to any one of claims 11 to 13, comprising a molding resin (40) for linking a plurality of the granules.

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