Metal magnetic powder, composite magnetic body, and electronic component

Abstract

Provided is a metal magnetic powder containing Co as a main component, wherein the metal magnetic powder contains metal nanoparticles having an average particle diameter (D50) of 1 nm or more and 100 nm or less. The main phase of each metal nanoparticle is hcp-Co, and the metal magnetic powder contains fcc-Co or / and ε-Co as a secondary phase.

Description

TECHNICAL FIELD

[0001] The present application relates to a metal magnetic powder containing metal nanoparticles mainly composed of Co, a composite magnetic body, and an electronic component. BACKGROUND

[0002] In recent years, in high-frequency circuits included in various communication devices such as mobile phones or wireless LAN devices, the operating frequency reaches the gigahertz band (for example, the 3.7 GHz band (3.6 to 4.2 GHz), the 4.5 GHz band (4.4 to 4.9 GHz band)). As electronic components mounted on such high-frequency circuits, for example, inductors, antennas, filters for coping with high-frequency noise, and the like are cited. In a coil built in an electronic component for such high-frequency use, an air-core coil having a non-magnetic core is generally used, but in order to improve the characteristics of the electronic component, development of a magnetic material that can be applied to an electronic component for high-frequency use is required.

[0003] For example, in Patent Literature 1, as a magnetic material for high frequencies, a magnetic material composed of metal nanoparticles is disclosed. Metal nanoparticles can reduce the number of magnetic domains per unit particle compared to micrometer-sized metal magnetic particles, and can reduce eddy current loss at high frequencies. However, even the magnetic material of Patent Literature 1, when the operating frequency exceeds 1 GHz, the magnetic permeability is extremely reduced (Patent Literature 1 Figure 2 ), and the magnetic loss increases.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2006-303298 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present application was developed in view of the above-described actual situation, and aims to provide a metal magnetic powder having high magnetic permeability and low magnetic loss in a high-frequency region of the gigahertz band, and a composite magnetic body and an electronic component containing the same.

[0009] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS

[0010] In order to achieve the above-described object, the present application provides a metal magnetic powder,

[0011] the main component is Co,

[0012] contains metal nanoparticles having an average particle diameter (D50) of 1 nm or more and 100 nm or less,

[0013] the main phase of each of the above-described metal nanoparticles is hcp-Co,

[0014] The metal magnetic powder contains fcc-Co or / and ε-Co as a secondary phase.

[0015] The metal magnetic powder of the present application can achieve high permeability and low magnetic loss in the high frequency region of the gigahertz band by having the above characteristics.

[0016] The proportion of the hcp-Co in the metal magnetic powder is set to W hcp The proportion of the fcc-Co is set to W fcc The proportion of the ε-Co is set to W ε ,

[0017] Preferably, W hcp / (W hcp +W fcc +W ε ) is 70% or more and 99% or less.

[0018] Preferably, the average particle diameter (D50) of the metal nanoparticles is 1 nm or more and 70 nm or less.

[0019] Preferably, the metal magnetic powder contains Zn,

[0020] The Zn is present on the surface of the nanoparticles and / or inside the nanoparticles.

[0021] The composite magnetic body of the present application contains the metal magnetic powder and a resin.

[0022] By containing the metal magnetic powder, the composite magnetic body can appropriately achieve high permeability and low magnetic loss in the high frequency region of the gigahertz band.

[0023] Preferably, the composite magnetic body contains Zn.

[0024] The metal magnetic body and the composite magnetic body can be applied to electronic components such as inductors, antennas, filters, and the like mounted in high frequency circuits. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a schematic view showing a metal magnetic powder 1 of one embodiment of the present application.

[0026] Figure 2 is a schematic view showing a cross section of a composite magnetic body containing Figure 1 the metal magnetic powder 1 shown in FIG. 1.

[0027] Figure 3A is an example of an X-ray diffraction pattern of the metal magnetic powder 1.

[0028] Figure 3Bis an example of an X-ray diffraction pattern of the metal magnetic powder 1 containing Zn.

[0029] Figure 4 is an example of a cross-sectional view of an electronic component using the composite magnetic body 10 shown in FIG. 1. Figure 2

[0030] Explanation of symbols

[0031] 1…metal magnetic powder, 2…nanoparticle, 3, 3a, 3b, 3c…grain of amphoteric metal, 10…composite magnetic body, 6…resin, 100…inductor, 50…coil portion, 60, 80…external electrode DETAILED DESCRIPTION

[0032] Hereinafter, the present application will be described in detail based on the embodiments shown in the drawings.

[0033] (Metal magnetic powder 1)

[0034] The metal magnetic powder 1 of the present embodiment is composed of the nanoparticles 2, and the average particle diameter of the nanoparticles 2 (i.e., the average particle diameter of the metal magnetic powder 1) is 1 nm or more and 100 nm or less. The average particle diameter of the nanoparticles 2 can be calculated by measuring the equivalent circle diameter of each nanoparticle 2 using a transmission electron microscope (TEM). Specifically, the metal magnetic powder 1 is observed at a magnification of 500,000 times or more by the TEM, and the equivalent circle diameter of each nanoparticle 2 contained in the observed field is measured by image analysis software. At this time, it is preferable to measure the equivalent circle diameter of at least 500 nanoparticles 2, and the number-based cumulative frequency distribution is obtained based on the measurement results. Furthermore, in the cumulative frequency distribution, the equivalent circle diameter at which the cumulative frequency becomes 50% is calculated as the average particle diameter (D50) of the nanoparticles 2.

[0035] In addition, the average particle diameter (D50) of the nanoparticles 2 is preferably 70 nm or less, and more preferably 50 nm or less. The smaller the average particle diameter of the nanoparticles 2, the more the magnetic loss tan δ of the metal magnetic powder 1 tends to be reduced. The shape of the nanoparticles 2 is not particularly limited, but in the production method shown in the present embodiment, generally, the nanoparticles 2 having a spherical shape or a shape close to a sphere are obtained. In addition, a coating layer such as an oxide coating film or an insulating coating film can be formed on the surface of the nanoparticles 2.

[0036] The metal magnetic powder 1 contains cobalt (Co) as a main component. That is, the nanoparticles 2 are Co nanoparticles having Co as a main component. In addition, the "main component" refers to an element occupying 80 wt% or more in the metal magnetic powder 1. The metal magnetic powder 1 preferably contains 90 wt% or more of Co, and more preferably contains 93 wt% or more.

[0037] ​In addition, in the metal magnetic powder 1, at least one amphoteric metal is preferably contained in addition to Co (main component). The amphoteric metal refers to four elements of aluminum (Al), zinc (Zn), tin (Sn), and lead (Pb), and the metal magnetic powder 1 more preferably contains Zn as the amphoteric metal. The content of Co in the metal magnetic powder 1 is assumed to be W Co (wt%), and the content of the amphoteric metal is assumed to be W AM (wt%), W AM (wt%), W Co (wt%), and W AM is preferably 0.001% or more (10 ppm or more) and 10% or less, and more preferably 1% or more and 7% or less. In addition, in the case where the metal magnetic powder 1 contains two or more kinds of amphoteric metals, W AM is the total of the contents of the respective amphoteric metals.

[0038] Other trace elements such as Cl, P, C, Si, N, and O can also be contained in the metal magnetic powder 1. The total content of the other trace elements (elements other than Co and amphoteric metals) in the metal magnetic powder 1 is preferably 20 wt% or less.

[0039] The composition (W Co , W AM , W AM (wt%), W Co (wt%), and W AM ) of the metal magnetic powder 1 can be measured by using a composition analysis such as inductively coupled plasma emission spectroscopy (ICP-AES), X-ray diffraction (XRD), fluorescence X-ray analysis (XRF), energy dispersive X-ray analysis (EDS), or wavelength dispersive X-ray analysis (WDS), and is preferably measured by ICP-AES. In the composition analysis based on ICP-AES, first, a sample containing the metal magnetic powder 1 is taken in a glove box, and the sample is added to an acid solution such as HNO3 (nitric acid) and is heated to be dissolved. The sample thus dissolved is subjected to the composition analysis based on ICP-AES, and Co and each amphoteric metal contained in the sample are quantified.

[0040] In addition, the main component of the metal magnetic powder 1 can also be determined based on analysis by X-ray diffraction or the like. For example, the volume rate of each element contained in the metal magnetic powder 1 can be calculated by analysis by X-ray diffraction or the like, and the element having the highest volume rate is determined as the main component in the metal magnetic powder 1.

[0041] The main phase of the metal magnetic powder 1, i.e., the main phase of each nanoparticle 2, is hcp-Co. "hcp-Co" is not an alloy phase, but refers to a crystal phase of Co having a hexagonal closest packed structure. Bulk Co and Co particles of a micrometer order easily take an hcp structure, but in the case of a microparticle of Co of 100 nm or less, there is a tendency for the main phase to become fcc-Co (a face-centered cubic structure) or ε-Co (one of cubic crystals). In the present embodiment, the nanoparticle 2 having the main phase of hcp-Co is obtained by a prescribed production method described later.

[0042] In addition, the metal magnetic powder 1 has the main phase of hcp-Co, and, as a secondary phase of Co, contains fcc-Co or / and ε-Co. This secondary phase of Co is mixedly present within the particle of the nanoparticle 2 having the main phase of hcp-Co. That is, the nanoparticle 2 of a single phase composed of hcp-Co and the other nanoparticle of a single phase composed of fcc-Co or ε-Co are not mixedly present, and the metal magnetic powder 1 contains the nanoparticle 2 having a mixed phase structure (a structure in which the main phase and the secondary phase are contained within the particle) of Co. In the metal magnetic powder 1, all of the nanoparticle 2 can have the mixed phase structure, or the nanoparticle 2 of hcp-Co (the nanoparticle 2 of a single phase not containing the secondary phase of Co) and the nanoparticle 2 of the mixed phase structure (the nanoparticle 2 containing the secondary phase of Co) can be mixedly present. It is preferable that, of the nanoparticle 2 contained in the metal magnetic powder 1, 80% or more of the nanoparticle 2 have the mixed phase structure on a number basis.

[0043] The metal magnetic powder 1, by containing the secondary phase of Co within the particle of the nanoparticle 2, can ensure a high magnetic permeability and reduce magnetic loss at a high frequency band of 1 GHz or more as compared with the present.

[0044] Further, the "main phase" refers to a crystal phase occupying 50% or more in the metal magnetic powder 1. Specifically, the proportion of hcp-Co in the metal magnetic powder 1 is set as W hcp , the proportion of fcc-Co is set as W fcc , and the proportion of ε-Co is set as W ε . W hcp , W fcc , and W ε are set as 100%, and a crystal phase occupying 50% or more is set as the main phase. That is, in the case where 50% ≤ (W hcp / (W hcp +W fcc +W ε ), it is determined that the main phase of the metal magnetic powder 1 is hcp-Co. "W hcp / (W hcp +W fcc +W ε) is preferably 70% or more and 99% or less, and more preferably 80% or more and 99% or less. By setting the content ratio of the hcp-Co within the above range, high magnetic permeability and low magnetic loss can be more appropriately balanced.

[0045] In the metal magnetic powder 1, as the secondary phase of Co, either one of fcc-Co or ε-Co can be contained, or both fcc-Co and ε-Co can be contained.

[0046] The crystal structure of the metal magnetic powder 1 (i.e., the crystal structure of the nanoparticle 2) can be analyzed by X-ray diffraction (XRD). Figure 3A The (d) shown is an example of an XRD pattern of the metal magnetic powder 1. In addition, Figure 3A The (a) to (c) of the above are XRD patterns collected in the literature or databases such as ICDD, and the (a) is an XRD pattern of ε-Co, the (b) is an XRD pattern of fcc-Co, and the (c) is an XRD pattern of hcp-Co. In addition, Figure 3A The (e) of the above is an example of an XRD pattern of a metal magnetic powder corresponding to the comparative example.

[0047] In the 2θ / θ measurement by XRD, peaks of hcp-Co and fcc-Co are detected. Figure 3A After the XRD pattern of the metal magnetic powder 1 shown in the (d) of the above is obtained, profile fitting (peak separation) of the measured XRD pattern is performed using an XRD analysis software. Then, by collating the separated diffraction peaks with databases, the crystal phases contained in the metal magnetic powder 1 can be identified. In the (d) of the above, Figure 3A In the XRD pattern shown in the (d) of the above, the peak indicated by "▼" is a diffraction peak derived from hcp-Co, and the peak indicated by "▽" is a diffraction peak derived from fcc-Co.

[0048] In addition, the proportion of the Co crystal phase can be calculated based on the integrated intensity of the diffraction peak. Specifically, after the diffraction peaks contained in the XRD pattern (d) are identified by profile fitting, the integrated intensity of the identified diffraction peaks is calculated. W hcp is the integrated intensity of the diffraction peak derived from hcp-Co, W fcc is the integrated intensity of the diffraction peak derived from fcc-Co, and W ε is the integrated intensity of the diffraction peak derived from ε-Co, and as long as "W hcp / (W hcp +W fcc +W ε )" is calculated.

[0049] In the XRD pattern (d) of the above, Figure 3A In the XRD pattern (d) of the above, the diffraction peak of hcp-Co and the diffraction peak of fcc-Co are detected, and the proportion of hcp-Co (W hcp / (Whcp +W fcc +W ε The percentage of fcc-Co was 95.1%, and the ratio of fcc-Co was (W). fcc / (W hcp +W fcc +W ε The figure is 4.9%. That is, in... Figure 3A In (d) the metallic magnetic powder 1, the main phase is hcp-Co and the secondary phase is fcc-Co.

[0050] In the equivalent of a comparative example Figure 3A In the XRD pattern (e), diffraction peaks of hcp-Co and fcc-Co were also detected, but the peak intensities near 2θ = 43.9° and 51.2° were higher in XRD pattern (e) than in (d). More specifically, in XRD pattern (e), the ratio of hcp-Co to fcc-Co (W) was higher. hcp / (W hcp +W fcc +W ε The percentage of fcc-Co was 38.6%, and the ratio of fcc-Co (W) was... fcc / (W hcp +W fcc +W ε The figure is 61.4%. That is, in... Figure 3A In the comparative example of the metallic magnetic powder (e), the main phase is fcc-Co and the secondary phase is hcp-Co.

[0051] Furthermore, in hcp-Co, which is the main phase of the metallic magnetic powder 1, a small amount of amphoteric metals and impurity elements may be dissolved. However, the deviation of the lattice constant of hcp-Co is preferably less than 0.5%. The "deviation of the lattice constant" is determined by (|d STD -d f |) / d STD (%) indicates that d STD d represents the lattice constant of hcp-Co recorded in the database. f The lattice constant of hcp-Co was calculated to analyze the XRD pattern of metallic magnetic powder 1. The lattice constant can also be determined by electron line diffraction using TEM.

[0052] In addition, the presence or absence of the mixed-phase structure within the nanoparticles 2 can be confirmed by analysis using a high-resolution electron microscope (HRTEM), electron backscatter diffraction (EBSD), or electron beam diffraction of TEM. For example, in the case where the crystalline structure of each nanoparticle 2 is analyzed using electron beam diffraction of TEM, an electron beam is irradiated to at least 50 nanoparticles 2, and based on the electron beam diffraction pattern obtained at this time, it is determined whether each nanoparticle 2 has a single-phase structure or a mixed-phase structure. Furthermore, in this analysis, it is preferable to select as many as possible of the nanoparticles 2 that are isolated within the field of view and irradiate an electron beam thereto.

[0053] Furthermore, in the analysis of the crystalline structure of the metal magnetic powder 1, it is also possible to first determine the crystalline structure of the nanoparticles 2 by electron beam diffraction of TEM, and then, based on the results of the analysis by electron beam diffraction, to calculate the ratio of the Co crystal phase by XRD.

[0054] In the case where the metal magnetic powder 1 contains the amphoteric metal, the amphoteric metal is preferably present as the grain 3 of the amphoteric metal, rather than being solid-solved in the main phase (hcp-Co) or being contained in a compound such as an oxide. In other words, the metal magnetic powder 1 preferably contains the grain 3 of the amphoteric metal, and particularly more preferably contains the grain (3) of Zn.

[0055] In the case where the metal magnetic powder 1 contains the grain 3 of the amphoteric metal, in the XRD pattern of the metal magnetic powder 1, not only the diffraction peak of the Co crystal phase but also the diffraction peak of the amphoteric metal is detected. In fact, Figure 3B (a) to (c) of FIG. 10 are the XRD patterns of the metal magnetic powder 1 containing Zn as the amphoteric metal. Furthermore, Figure 3B (a) to (c) of FIG. 10 are the XRD patterns of the metal magnetic powder 1 containing Zn as the amphoteric metal. Furthermore, Figure 3A are the same as the diffraction peaks of each Co crystal phase included in the literature or database such as ICDD, Figure 3B (d) is the diffraction peak of Zn included in the database.

[0056] In the XRD pattern (e) of FIG. 10, Figure 3B In the XRD pattern (e) of FIG. 10, the diffraction peak of Zn (the peak indicated by "O" is the diffraction peak of Zn) is detected together with the diffraction peak of hcp-Co. That is, in the metal magnetic powder 1 shown in (e), Figure 3B In the metal magnetic powder 1 shown in (e) of FIG. 10, it is known that Zn is not present as a compound such as an oxide but is present as a metal crystal. In this way, the state of existence of the amphoteric metal can be confirmed by analysis of the XRD pattern.

[0057] In addition, in the case where the metal magnetic powder 1 contains an amphoteric metal, the amphoteric metal is preferably present inside the nanoparticles 2 or / and on the surface of the nanoparticles 2. That is, the metal magnetic powder 1 preferably contains the grains 3 of the amphoteric metal present inside the nanoparticles 2 or / and on the surface of the nanoparticles 2. In addition, the grain size of the grains 3 of the amphoteric metal is preferably smaller than the average particle size of the nanoparticles 2. The site where the amphoteric metal is present can be determined, for example, by mapping analysis using TEM-EDS.

[0058] (Composite magnetic body 10)

[0059] Next, the composite magnetic body 10 containing the above-described metal magnetic powder 1 will be described. Figure 2 The composite magnetic body 10 containing the above-described metal magnetic powder 1 will be described.

[0060] The composite magnetic body 10 contains the metal magnetic powder 1 having the above-described characteristics and the resin 6, and the nanoparticles 2 constituting the metal magnetic powder 1 are dispersed in the resin 6. In other words, the resin 6 is interposed between the nanoparticles 2, and insulates between adjacent particles. The resin 6 is a resin material having insulating properties, and the material is not particularly limited. For example, as the resin 6, a thermosetting resin such as an epoxy resin, a phenol resin, a silicone resin, or a thermoplastic resin such as an acrylic resin, polyethylene, or polypropylene can be used, and a thermosetting resin is preferable.

[0061] The area ratio of the metal magnetic powder 1 on the cross section of the composite magnetic body 10 is preferably 10% to 60%, and more preferably 10% to 40%.

[0062] The area ratio of the metal magnetic powder 1 on the cross section of the composite magnetic body 10 can be calculated by observing the cross section of the composite magnetic body 10 using a scanning electron microscope (SEM) and a transmission electron microscope (TEM), and analyzing the cross-sectional image using image analysis software. Specifically, the cross-sectional image of the composite magnetic body 10 is binarized based on the contrast, the metal magnetic powder and other portions are distinguished, and the area ratio of the metal magnetic powder 1 with respect to the entire image (i.e., the area of the observed field) is calculated. The area ratio calculated by the above-described method can be considered as the volume ratio of the nanoparticles 2 contained in the composite magnetic body 10.

[0063] In the case where the metal magnetic powder 1 contains an amphoteric metal, the amphoteric metal is preferably present as the grains 3 inside the composite magnetic body 10. More specifically, the grains 3 of the amphoteric metal can be present inside the nanoparticles 2 and on the surface of the nanoparticles 2. Also, the grains 3 of the amphoteric metal can be dispersed in the resin 6 of the composite magnetic body 10 (grains 3c). The grains 3c present in the resin 6 are considered to be generated by peeling off the grains 3b attached to the surface of the nanoparticles 2 from the particle surface during the mixing of the metal magnetic powder 1 and the resin 6.

[0064] That is, as the site where the amphoteric metal exists in the composite magnetic body 10, there are three sites of A: the inside of the nanoparticle 2, B: the surface of the nanoparticle 2, and C: the resin 6. The amphoteric metal in the composite magnetic body 10 can exist in any one of A to C, can exist in any two of A to C, or can exist in all of A to C. The site where the amphoteric metal exists in the composite magnetic body 10 can be determined by performing mapping analysis based on TEM-EDS on the cross section of the composite magnetic body 10.

[0065] Further, even in the case where the metal magnetic powder 1 is contained in the composite magnetic body 10, the average particle diameter (D50), the composition, and the crystal structure of the metal magnetic powder 1 can be analyzed by the above-described methods (TEM observation, ICP-AES, XRD, etc.). Further, when the composition of the metal magnetic powder 1 contained in the composite magnetic body 10 is analyzed by ICP-AES or XRD, etc., the constituent elements of the resin 6 can sometimes have an influence. In this case, the influence of the elements other than Co and the amphoteric metal can be excluded, and the main component of the metal magnetic powder 1 can be determined based on W AM / (W Co +W AM only.

[0066] The composite magnetic body 10 can also contain ceramic particles, metal particles other than the nanoparticle 2, etc. Further, the shape and the size of the composite magnetic body 10 are not particularly limited, and can be appropriately determined according to the use.

[0067] Hereinafter, an example of the method of producing the metal magnetic powder 1 and the composite magnetic body 10 will be described. The metal magnetic powder 1 of the present embodiment is preferably produced by a thermal decomposition method in a gas phase or a thermal decomposition method in a liquid phase with a disproportionation reaction.

[0068] (Method of producing the metal magnetic powder 1 by the thermal decomposition method in a gas phase)

[0069] The thermal decomposition method is a method of generating a nanoparticle of Co by heating a complex of cobalt as a precursor to thermally decompose it. Conventionally, the precursor is dispersed in a solvent such as dichlorobenzene or ethylene glycol, and the reaction solution is heated to a high temperature of about 180°C to thermally decompose the precursor in a liquid phase (i.e., a thermal decomposition method in a liquid phase). In the present embodiment, the precursor is not used with a solvent, but is thermally decomposed in a gas phase in an inert atmosphere (i.e., a thermal decomposition method in a gas phase). In the conventional thermal decomposition method in a liquid phase, the main phase of the nanoparticle easily becomes fcc-Co or ε-Co, in contrast to which, in the thermal decomposition method in a gas phase, a nanoparticle 2 having a main phase of hcp-Co can be obtained.

[0070] In the thermal decomposition in a gas phase, a reaction vessel into which a precursor as a raw material is put is set in an oil bath, and the reaction vessel is heated in an inert atmosphere to thermally decompose the precursor. At this time, the raw material in the reaction vessel is stirred using a mechanical stirrer or the like. As the cobalt complex of the precursor, Co2(CO)8or Co4(CO) 12 is preferably used, and Co2(CO)8is more preferably used. As the reaction vessel, for example, a separable flask can be used, and the material of the reaction vessel is not particularly limited. In addition, in the thermal decomposition atmosphere, an inert gas such as Ar gas or N2gas is filled, and the kind of the inert gas used is not particularly limited.

[0071] In the case where the amphoteric metal is added to the metal magnetic powder 1, the raw material of the amphoteric metal is put into the reaction vessel together with the precursor. As the raw material of the amphoteric metal, a chloride of the amphoteric metal such as ZnCl2, AlCl3, SnCl2, and PbCl2is preferably used. The ratio (W AM / (W AM +W Co ) of the amphoteric metal in the metal magnetic powder 1 can be controlled by the blending ratio of the above raw materials. In addition, a surfactant such as oleic acid or a silane coupling agent can be added at the time of the thermal decomposition reaction. As the silane coupling agent, for example, a silane coupling agent containing an aniline structure or / and a phenyl group is preferably used, and N-phenyl-3-aminopropyltrimethoxysilane is more preferably used.

[0072] In the case where the surfactant is not added, the reaction temperature (i.e., the heating temperature of the raw material) in the thermal decomposition in a gas phase can be set to 57°C or higher and 180°C or lower, preferably 57°C or higher and 120°C or lower, and more preferably 57°C or higher and 80°C or lower. On the other hand, in the case where the surfactant is added, the reaction temperature can be set to 52°C or higher and 150°C or lower, preferably 57°C or higher and 120°C or lower, and more preferably 57°C or higher and 80°C or lower. The higher the reaction temperature, the more the average particle diameter of the nanoparticles 2 tends to become large. If the reaction temperature is low, the average particle diameter of the nanoparticles 2 tends to become small, and the ratio of the hcp-Co tends to become high.

[0073] The reaction time in the thermal decomposition in a gas phase is preferably appropriately adjusted according to the reaction temperature. For example, in the case where the reaction temperature is 150°C to 180°C, the reaction time is preferably 0.01 h to 3.5 h, in the case where the reaction temperature is 100°C or higher and lower than 150°C, the reaction time is preferably 0.1 h to 10 h, and in the case where the reaction temperature is lower than 100°C, the reaction time is preferably 0.25 h to 96 h, and more preferably 1 h to 50 h. The longer the reaction time, the more the average particle diameter of the nanoparticles 2 tends to become large.

[0074] The crystal structure of the nanoparticles 2 can be controlled depending on the kind of the surfactant and the reaction temperature, etc. For example, in the case where no surfactant is added, the higher the reaction temperature, the more easily fcc-Co is generated as a by-product phase. In the case where oleic acid is added as a surfactant, ε-Co is easily generated as a by-product phase, and if the reaction temperature is high, the ratio of ε-Co tends to increase. On the other hand, in the case where N-phenyl-3-aminopropyltrimethoxysilane, a silane coupling agent, is added as a surfactant, both of fcc-Co and ε-Co are easily obtained as by-product phases, and if the reaction temperature is high, the ratio of the by-product phases increases.

[0075] In the case where the amphoteric metal is added to the metal magnetic powder 1, the raw material of the amphoteric metal can be added at the start of the reaction or after a prescribed time from the start of the reaction. The site where the amphoteric metal exists can be controlled by the timing of adding the raw material of the amphoteric metal. Specifically, in the case where the raw material of the amphoteric metal is added at the start of the reaction, the amphoteric metal easily exists in the particle of the nanoparticles 2. On the other hand, if the raw material of the amphoteric metal is added in the middle of the thermal decomposition reaction, the amphoteric metal adheres to the surface of the nanoparticles 2, and the later the timing of adding the raw material of the amphoteric metal, the more the proportion of the amphoteric metal existing on the surface of the nanoparticles 2 tends to increase. Specifically, the final reaction time is set to RT, and in the case where the raw material of the amphoteric metal is added after (2 / 3)RT or more from the start of the reaction, the amphoteric metal tends to exist on the surface of the nanoparticles 2 as compared with the particle.

[0076] After the thermal decomposition reaction in the gas phase is continued for a desired time, the reaction vessel is taken out of the oil bath, and the product is naturally cooled to room temperature. After the cooling, the generated nanoparticles 2 are washed and recovered using a washing solvent. As the washing solvent, an organic solvent such as acetone, dichlorobenzene, or ethanol can be used, and in order to suppress oxidation of the nanoparticles 2, it is preferable to perform a degassing treatment on the washing solvent. Alternatively, as the washing solvent, it is preferable to use an organic solvent of an ultradewater grade in which the moisture content is suppressed to 10 ppm or less. Further, the recovery of the nanoparticles 2 can be performed using a magnet. Through the above procedures, the metal magnetic powder 1 can be obtained.

[0077] Further, the series of procedures from the weighing of the raw materials to the washing and recovery of the nanoparticles are performed in an atmosphere of an inert gas such as Ar.

[0078] (Method for producing a metal magnetic powder 1 by thermal decomposition in a liquid phase accompanied by a disproportionation reaction)

[0079] The disproportionation reaction refers to a reaction in which two or more molecules of a substance react with each other to produce two or more other substances. In the case of producing the metal magnetic powder 1 by the thermal decomposition in the liquid phase with the disproportionation reaction, it is preferable to use chloro tris(triphenylphosphine) cobalt (CoCl(Ph3P)3) as the precursor (Co raw material). In the thermal decomposition in the liquid phase with the disproportionation reaction, both Co(O)(Ph3P)4and Co(II)Cl2(Ph3P)2are produced from the precursor, and the nanoparticles 2 of Co are produced by decomposing the Co(O)(Ph3P)4in the compound. This production method is also the same as the thermal decomposition in the gas phase, and it is preferable to add the raw material of the amphoteric metal such as ZnCl2.

[0080] In the case of producing the metal magnetic powder 1 by the thermal decomposition in the liquid phase with the disproportionation reaction, first, the precursor and the raw material of the amphoteric metal are weighed so that the metal magnetic powder 1 becomes the desired composition. Then, the precursor, the raw material of the amphoteric metal, and the solvent are put into a reaction vessel such as a separable flask, and these raw materials are stirred using a mechanical stirrer or the like. The ratio (W AM / (W AM +W Co ) of the amphoteric metal in the metal magnetic powder 1 can be controlled by the mixing ratio of the above raw materials. As the solvent, it is preferable to use ethanol, tetrahydrofuran (THF), or oleylamine (oleylamine). In addition, a surfactant such as oleic acid can be added.

[0081] The atmosphere at the time of synthesizing the nanoparticles 2 is preferably an inert gas atmosphere such as an Ar atmosphere or an N2 atmosphere. In the case of using ethanol as the solvent, the temperature of the reaction liquid at the time of stirring (i.e., the reaction temperature) is preferably 25°C (room temperature) or higher and 65°C or lower. On the other hand, in the case of using THF or oleylamine as the solvent, the reaction temperature can be 10°C or higher and 65°C or lower, and is preferably 25°C (room temperature) or higher and 40°C or lower. The higher the reaction temperature, the more the average particle diameter of the nanoparticles 2 tends to become larger.

[0082] In addition, the stirring time (i.e., the reaction time) is desirably adjusted appropriately according to the reaction temperature, and is, for example, preferably 0.01 h to 80 h, and more preferably 0.1 h to 72 h in the case of the reaction temperature being room temperature. The longer the reaction time, the more the average particle diameter of the nanoparticles 2 tends to become larger.

[0083] In the case of producing the metal magnetic powder 1 by the thermal decomposition in the liquid phase with the disproportionation reaction, the crystal structure of the nanoparticles 2 can be controlled according to the kind of the solvent and the reaction temperature, and the like. For example, the lower the reaction temperature, the more the ratio (W hcp / (W hcp +W fcc +W ε))The higher the reaction temperature, the higher the tendency to generate a secondary phase (fcc-Co or / and ε-Co). In the case of using ethanol as the solvent, the ratio of hcp-Co tends to be higher than in the case of using other solvents (THF or oleylamine), and at a reaction temperature of 25°C or higher, fcc-Co tends to be generated as a secondary phase. In the case of using THF as the solvent, a mixed phase structure of the primary phase hcp-Co and the secondary phase fcc-Co is easily obtained. In the case of using oleylamine as the solvent, there is a tendency to obtain a mixed phase structure of the primary phase hcp-Co and the secondary phases fcc-Co and ε-Co. In the case of using oleylamine and setting the reaction temperature to be higher than 40°C, a mixed phase structure of the primary phase hcp-Co and the secondary phase ε-Co is easily obtained.

[0084] In the thermal decomposition in the liquid phase accompanying the disproportionation reaction, the amphoteric metal raw material can be added at the start of the reaction or after a prescribed time has elapsed from the start of the reaction. The site where the amphoteric metal is present can be controlled by the timing of adding the amphoteric metal raw material. Specifically, in the case of adding the amphoteric metal raw material at the start of the reaction, the amphoteric metal tends to be present in the particle of the nanoparticle 2. On the other hand, if the amphoteric metal raw material is added midway through the thermal decomposition reaction, the amphoteric metal adheres to the surface of the nanoparticle 2, and the later the timing of adding the amphoteric metal raw material, the greater the tendency of the amphoteric metal to be present on the surface of the nanoparticle 2. Specifically, setting the final reaction time to be RT, in the case of adding the amphoteric metal raw material after 3 / 4RT or more has elapsed from the start of the reaction, the amphoteric metal tends to be present on the surface of the nanoparticle 2 compared to the particle.

[0085] After stopping the reaction liquid and stopping the reaction, the generated nanoparticle 2 is washed and recovered. In washing the nanoparticle 2, a soluble washing solvent such as an unreacted raw material or an intermediate product is used. Specifically, as the washing solvent, an organic solvent such as acetone, dichlorobenzene, or ethanol can be used. In order to suppress oxidation of the nanoparticle 2, it is preferable to perform a degassing treatment on the washing solvent. Alternatively, as the washing solvent, it is preferable to use an organic solvent of an ultradewater grade in which the moisture content is suppressed to 10 ppm or less. Furthermore, the recovery of the nanoparticle 2 can be performed using a magnet. Through the above procedures, the metal magnetic powder 1 can be obtained.

[0086] Furthermore, the entire series of procedures from the weighing of the raw materials to the washing and recovery of the nanoparticle are performed in an inert gas atmosphere such as an Ar atmosphere.

[0087] (Method for manufacturing composite magnetic body 10)

[0088] Next, an example of a method for manufacturing the composite magnetic body 10 will be described.

[0089] The composite magnetic body 10 can be produced by mixing the metal magnetic powder 1, the resin 6, and a solvent, and performing a prescribed dispersion treatment. As the dispersion treatment, ultrasonic dispersion treatment or media dispersion treatment using a bead mill or the like is preferable. The conditions of the dispersion treatment are not particularly limited, and various conditions can be set so that the nanoparticles 2 are uniformly dispersed in the resin 6. As the solvent to be added at the time of the dispersion treatment, an organic solvent such as acetone, dichlorobenzene, or ethanol can be used, and a degassed organic solvent or an organic solvent of a super-dehydrated grade is preferably used. In addition, as the media to be used at the time of the media dispersion treatment, various ceramic beads can be used, and beads of Zr02having a large specific gravity are preferably used even among the ceramic beads.

[0090] Further, the site of the amphoteric metal in the composite magnetic body 10 sometimes changes due to the dispersion treatment. For example, in the case where ultrasonic dispersion treatment is performed, the amphoteric metal attached to the surface of the nanoparticles 2 is difficult to peel off, but in the case where media dispersion treatment is performed, the amphoteric metal attached to the surface of the nanoparticles 2 is easily peeled off. Therefore, the longer the time of the media dispersion treatment, the more the proportion of the amphoteric metal dispersed in the resin 6 tends to increase.

[0091] The slurry obtained in the above-described dispersion treatment is dried in an inert atmosphere such as an Ar atmosphere, to obtain a dried body from which the solvent has been volatilized. Then, the dried body is pulverized using a mortar or a dry-type pulverizer or the like, to obtain particles containing the metal magnetic powder 1 and the resin 6. Then, the composite magnetic body 10 is obtained by filling the particles into a mold and applying pressure. Further, in the case where a thermosetting resin is used as the resin 6, it is preferable to perform a curing treatment on the composite magnetic body after pressure molding. The method of producing the composite magnetic body is not limited to the above-described pressure molding method. For example, a sheet-shaped composite magnetic body 10 can also be obtained by coating the slurry obtained in the dispersion treatment on a PET film and drying it.

[0092] Further, the series of processes for obtaining the composite magnetic body 10 are also performed in an inert atmosphere such as an Ar atmosphere, as in the production of the metal magnetic powder 1.

[0093] (Summary of Embodiments)

[0094] The metallic magnetic powder 1 of this embodiment is composed of nanoparticles 2 with hcp-Co as the main phase and an average particle size (D50) of 1 nm to 100 nm (preferably 1 nm to 70 nm). Furthermore, the metallic magnetic powder 1 contains fcc-Co and / or ε-Co as secondary phases. By including the mixed-phase nanoparticles 2 in the metallic magnetic powder 1, high permeability can be ensured at high frequencies above 1 GHz, and magnetic loss is reduced compared to current methods. Additionally, regarding the composite magnetic body 10, by including the metallic magnetic powder 1 with the above characteristics, high permeability and low magnetic loss can be appropriately balanced at high frequencies.

[0095] In the metallic magnetic powder 1 and the composite magnetic body 10, W hcp / (W hcp +W fcc +W ε The ratio of hcp-Co, which is the main phase, is between 70% and 99%. Since the ratio of hcp-Co, which is the main phase, meets the above requirements, it is possible to more appropriately balance high permeability and low magnetic loss at high frequencies.

[0096] Furthermore, the metallic magnetic powder 1 and the composite magnetic body 10 contain crystals of amphoteric metals (preferably Zn crystals). By adding an amphoteric metal to the metallic magnetic powder 1, which is composed of nanoparticles 2 having a mixed-phase structure of Co, magnetic loss can be further reduced.

[0097] Both the metallic magnetic powder 1 and the composite magnetic body 10 can be used for various electronic components such as inductors, transformers, choke coils, filters and antennas, and are particularly suitable for electronic components for high-frequency circuits with operating frequencies of 1 GHz or higher (more preferably 1 GHz to 10 GHz).

[0098] As an electronic component comprising metallic magnetic powder 1 (or composite magnetic body 10), examples include Figure 4 The inductor 100 is shown. The base of the inductor 100 is composed of the composite magnetic body 10 of this embodiment, and a coil portion 50 is embedded inside the base. A pair of external electrodes 60 and 80 are formed on the end face of the base, and each external electrode 60 and 80 is electrically connected to the lead-out portions 50a and 50b of the coil portion 50, respectively. Electronic components such as the inductor 100 have excellent high-frequency characteristics because they contain the metallic magnetic powder 1 (composite magnetic body 10) of this embodiment.

[0099] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

[0100] Example

[0101] The present application will be described in more detail based on specific examples below. However, the present application is not limited to the examples below.

[0102] (Experiment 1)

[0103] In Experiment 1, metal magnetic powders of Samples Al to A18 were produced by a thermal decomposition method in a gas phase. Specifically, Co2(CO)8 as a precursor was put into a separable flask, and the precursor was heated to 57°C while being stirred using a mechanical stirrer. An oil bath was used in the heating of the separable flask, but no solvent was added inside the separable flask, and the precursor was thermally decomposed in a gas phase. The atmosphere at this time was an Ar atmosphere, and the reaction time in each sample was set to the values shown in Table 1.

[0104] In Samples Al to A6, no surfactant was added, and the precursor was thermally decomposed, in Samples A7 to A12, oleic acid was added as a surfactant at the time of thermal decomposition, and in Samples A13 to A18, N-phenyl-3-aminopropyltrimethoxysilane, a silane coupling agent, was added as a surfactant at the time of thermal decomposition.

[0105] After the nanoparticles were synthesized by thermal decomposition, the separable flask was left to stand at room temperature, and the generated nanoparticles were naturally cooled to room temperature. After cooling, the nanoparticles were washed using super-dehydrated acetone and recovered by a magnet. Furthermore, the series of operations from the weighing of the raw material to the washing and recovery were performed under an Ar atmosphere. The metal magnetic powders of Samples Al to A18 were obtained by the above procedures.

[0106] Next, using the above metal magnetic powders, a composite magnetic body was produced. Furthermore, the production method of the composite magnetic body was common in Samples Al to A18.

[0107] First, the metal magnetic powder was weighed so that the content rate of the nanoparticles in the composite magnetic body would be 10 vol%. Then, the weighed metal magnetic powder, an epoxy resin, and acetone as a solvent were mixed, and the mixture was subjected to ultrasonic dispersion treatment. The treatment time of the ultrasonic dispersion was 10 min, and the dispersion liquid obtained by the ultrasonic dispersion treatment was dried under an Ar atmosphere at 50°C, thereby obtaining a dried body. Furthermore, after the dried body was pulverized with a mortar, the obtained particles were filled into a mold and subjected to pressurization, thereby obtaining a composite magnetic body. The composite magnetic body in each sample had a ring shape with an outer shape of 7 mm, an inner diameter of 3 mm, and a thickness of 1 mm. The series of procedures for producing the composite magnetic body were performed under an Ar atmosphere.

[0108] The composite magnetic body of each sample in Experiment 1 was subjected to the evaluations shown below.

[0109] Average particle diameter of the nanoparticles

[0110] The nanoparticles produced in each sample of Experiment 1 were observed at a magnification of 500,000 times using a TEM (manufactured by JEOL Ltd.: JEM-2100F). Then, the equivalent circle diameters of 500 nanoparticles were measured by image analysis software, and the average particle diameter (D50) was calculated.

[0111] Crystal structure analysis

[0112] First, in the TEM observation, 50 nanoparticles isolated in the field of view were irradiated with an electron beam, and an electron beam diffraction pattern was obtained. Then, based on the obtained electron beam diffraction pattern, it was identified whether each nanoparticle had a single-phase structure or a mixed-phase structure. In each sample Al to Al 8 of Experiment 1, it was confirmed that the nanoparticles had a mixed-phase structure.

[0113] In addition, by 2θ / θ measurement using an XRD device (manufactured by Rigaku Corporation: Smart Lab), an XRD pattern of the composite magnetic body was obtained. Then, the obtained XRD pattern was analyzed by X-ray analysis integrated software (Smart Lab Studio II), and the ratios of hcp-Co, fcc-Co, and ε-Co (W hcp , W fcc , and W ε ) were calculated. Furthermore, in this analysis, the total of hcp-Co, fcc-Co, and ε-Co was set to 100%, and the ratio of each Co crystal phase was estimated.

[0114] Evaluation of magnetic properties

[0115] By a coaxial S parameter method using a network analyzer (manufactured by Agilent Technologies, Inc.: HP8753D), the real part (i.e., permeability μ' (unitless)) and the imaginary part μ" of the complex permeability at 5 GHz were measured. Then, the magnetic loss tan δ (unitless) at 5 GHz was calculated as μ" / μ'. The permeability μ' and the magnetic loss tan δ also vary depending on the content rate of the nanoparticles in the composite magnetic body. As with each sample of Experiment 1, in the case where the content rate of the nanoparticles in the composite magnetic body is 10 vol%, a sample in which the permeability μ' is 1.15 or more and the magnetic loss tan δ is 0.100 or less was judged to be "good".

[0116] Table 1 shows the evaluation results of each sample in Experiment 1.

[0117] [Table 1]

[0118]

[0119] As shown in Table 1, in the case where the reaction temperature (thermal decomposition temperature) was set to 57°C, in the samples (Examples) in the range of 1 to 96 h of the reaction time, nanoparticles having an average particle diameter (D50) of 1 nm to 100 nm and having a mixed phase structure were obtained. In the samples A6, A12, and A18 (Comparative Examples) in which the reaction time was 120 h, although the nanoparticles had a mixed phase structure, the average particle diameter (D50) of the nanoparticles was also greater than 100 nm. In the samples A6, A12, and A18 as Comparative Examples, both the magnetic permeability and the magnetic loss also did not satisfy the evaluation criteria. On the other hand, in the Examples (samples Al to A5, A7 to Al l, A13 to Al 7) in which the average particle diameter (D50) was in the range of 1 nm to 100 nm, the magnetic permeability characteristics and the magnetic loss characteristics were improved compared to the Comparative Examples, and good magnetic characteristics were obtained at 5 GHz.

[0120] Further, in the Examples shown in Table 1, the smaller the average particle diameter, the lower the magnetic loss. That is, it was found that in the nanoparticles having a mixed phase structure in which the main phase was hcp-Co, the average particle diameter was preferably 72 nm or less, and more preferably 52 nm or less.

[0121] In addition, according to the evaluation results shown in Table 1, it was found that by adding a surfactant, the crystal structure of the Co nanoparticles changed. Specifically, it was found that in the case where no surfactant was added (samples Al to A6), fcc-Co was generated as a secondary phase, and the ratio of hcp-Co as the main phase was higher compared to the case where a surfactant was added. On the other hand, it was found that in the case where oleic acid was added as a surfactant (samples A7 to A12), ε-Co was generated as a secondary phase, and in the case where N-phenyl-3-aminopropyltrimethoxysilane was added as a surfactant (samples A13 to Al 8), fcc-Co and ε-Co were generated as secondary phases.

[0122] (Experiment 2)

[0123] In Experiment 2, the reaction temperature at the time of thermal decomposition was changed, and metal magnetic powders were manufactured under the conditions shown in Tables 2 to 4. In each of the samples Bl to B28 shown in Table 2 (and Al to A6 of Experiment 1), no surfactant was added, and Co2(CO)8 as a precursor was thermally decomposed in the gas phase to obtain a metal magnetic powder. On the other hand, in each of the samples Cl to C28 shown in Table 3 (and A7 to A12 of Experiment 1), oleic acid was added to manufacture a metal magnetic powder of Co, and in Dl to D28 shown in Table 4 (and A13 to Al 8 of Experiment 1), N-phenyl-3-aminopropyltrimethoxysilane, a silane coupling agent, was added to manufacture a metal magnetic powder.

[0124] The metal magnetic powder and the composite magnetic body of each sample of Experiment 2 were produced under the same production conditions as those of Experiment 1 except for the reaction temperature and the reaction time. Tables 2 to 4 show the evaluation results of each sample of Experiment 2.

[0125] [Table 2]

[0126]

[0127] [Table 3]

[0128]

[0129] [Table 4]

[0130]

[0131] From the evaluation results of Tables 2 to 4, it is found that the higher the reaction temperature at the time of thermal decomposition in the gas phase, the more easily the by-phase is generated, and the ratio of the hcp-Co decreases. In other words, the lower the reaction temperature at the time of thermal decomposition in the gas phase, the higher the ratio of the hcp-Co.

[0132] In the samples B1 to B6 (comparative examples) shown in Table 2, no surfactant was added, and the precursor was thermally decomposed at 52°C, thereby obtaining a metal magnetic powder not containing a by-phase. In the samples B1 to B6, although the magnetic loss was 0.100 or less, the magnetic permeability was lower than 1.15 (the reference value), and the evaluation criteria of the magnetic characteristics could not be satisfied. In the case where the reaction temperature was set to 57°C to 180°C without using a surfactant, a mixed phase structure containing a main phase of the hcp-Co (a crystal phase occupying 50% or more of the nanoparticle) and a by-phase of the fcc-Co was obtained. Moreover, in the examples (samples Al to A5 and samples B7 to B28) in which the average particle diameter (D50) was in the range of 1 nm to 100 nm in the samples containing the nanoparticle of the mixed phase structure, high magnetic permeability and low magnetic loss could be balanced at 5 GHz.

[0133] In the samples C25 to C28 (comparative examples) shown in Table 3, oleic acid was added, and the precursor was thermally decomposed at a high temperature of 180°C, thereby obtaining a metal magnetic powder in which ε-Co was a main phase. In the samples C25 to C28 in which ε-Co was a main phase, although high magnetic permeability was obtained at 5 GHz, the magnetic loss was larger than 0.100, and the evaluation criteria of the magnetic characteristics could not be satisfied. In the case where oleic acid was added, by setting the reaction temperature to 52°C to 150°C, a mixed phase structure containing a main phase of the hcp-Co and a by-phase of the ε-Co was obtained. Moreover, in the examples (samples Cl to C5, A7 to Al l, and C7 to C24) in which the average particle diameter (D50) was in the range of 1 nm to 100 nm in the samples containing the nanoparticle of the mixed phase structure, high magnetic permeability and low magnetic loss could be balanced at 5 GHz.

[0134] In addition, in Samples D25 to D28 shown in Table 4, N-phenyl-3- aminopropyltrimethoxysilane was added, and the precursor was thermally decomposed at a high temperature of 180°C, thereby obtaining a metal magnetic powder having a ratio of hcp-Co of less than 50%. In the Samples D25 to D28, although high permeability was obtained at 5 GHz, the magnetic loss was greater than 0.100, and the evaluation criteria of the magnetic properties could not be satisfied. In the case where N-phenyl-3-aminopropyltrimethoxysilane was added, by setting the reaction temperature to 52°C to 150°C, a mixed phase structure including a main phase of hcp-Co, a secondary phase of fcc-Co, and a secondary phase of ε-Co was obtained. Furthermore, in the Examples (Samples D1 to D5, A13 to A17, and D7 to D24) in which the average particle diameter (D50) of the nanoparticles including the mixed phase structure was in the range of 1 nm to 100 nm, high permeability and low magnetic loss could be simultaneously satisfied at 5 GHz.

[0135] From the results of Tables 2 to 4 described above, it was found that by the Co nanoparticles including a main phase of hcp-Co and a secondary phase of fcc-Co or / and ε-Co in the range of the average particle diameter (D50) of 1 nm to 100 nm, high permeability and low magnetic loss could be simultaneously satisfied at a high frequency band. In addition, in the Examples shown in Tables 2 to 4, the higher the ratio of hcp-Co as the main phase, the lower the magnetic loss tended to be, and the higher the ratio of the secondary phase, the higher the permeability tended to be. It was found that the ratio (W hcp hcp fcc ε (W

[0136] (Experiment 3)

[0137] In Experiment 3, in order to evaluate in detail the influence of the mixed phase structure of the Co nanoparticles on the magnetic properties, composite magnetic bodies corresponding to Samples H1 to H8 of the Comparative Examples were manufactured.

[0138] Sample H1 (comparative example)

[0139] In Sample H1, a metal magnetic powder was manufactured by a thermal decomposition method in a liquid phase. First, Co2(CO)8 as a precursor and dichlorobenzene as a solvent were put into a separable flask, and a reaction liquid was obtained. Then, the separable flask was set in an oil bath, heated to 180°C, and the reaction liquid was stirred by a mechanical stirrer. That is, by thermally decomposing Co2(CO)8 in dichlorobenzene heated to 180°C, nanoparticles of Co were generated.

[0140] ​​​After stirring the reaction liquid for 0.5 hours, the separable flask was left to stand at room temperature, and the generated nanoparticles were naturally cooled to room temperature. After the cooling, the nanoparticles were washed with super-dehydrated acetone and recovered by a magnet. The metal magnetic powder of sample Hl (comparative example) was obtained by the above procedure. Further, the series of operations from the weighing of the raw materials to the washing and recovery were performed under an Ar atmosphere.

[0141] The results of confirming the crystal structure of the nanoparticles by electron diffraction of TEM revealed that in sample Hl, nanoparticles of a single phase composed of ε-Co were obtained. In sample Hl, using the metal magnetic powder, a composite magnetic body was manufactured under the same conditions as in Experiment 1.

[0142] Samples H2 to H4 (comparative examples)

[0143] In samples H2 to H4, the metal magnetic powder of sample B2 (comparative example) having a single phase structure of hcp-Co (hereinafter referred to as B2 powder) and the metal magnetic powder of sample Hl (comparative example) having a single phase structure of ε-Co (hereinafter referred to as Hl powder) were mixed, and a composite magnetic body was manufactured. The mixing ratio of the B2 powder and the Hl powder was controlled so that the ratio of the Co crystal phase in the mixed powder became the value shown in Table 5. Further, the manufacturing conditions of the composite magnetic body in samples H2 to H4 were the same as in Experiment 1 except that the mixed powder was used.

[0144] Sample H5 (comparative example)

[0145] In sample H5, when the metal magnetic powder was manufactured by the liquid phase thermal decomposition method, Co2(CO)8 was used as the precursor, tetrahydro naphthalene (1,2,3,4-tetrahydronaphthalene) was used as the solvent, and poly(N-vinyl-2-pyrrolidone) was used as the surfactant, and the reaction temperature was set to 200°C. The manufacturing conditions other than the above were the same as in sample Hl. The results of confirming the crystal structure of the nanoparticles by electron diffraction of TEM revealed that in sample H5, nanoparticles of a single phase composed of fcc-Co were obtained. In sample H5, using the metal magnetic powder, a composite magnetic body was manufactured under the same conditions as in Experiment 1.

[0146] Samples H6 to H8 (comparative examples)

[0147] In Samples H6 to H8, B2 powder having a single-phase structure of hcp-Co and metallic magnetic powder of Sample H5 (hereinafter referred to as H5 powder) having a single-phase structure of fcc-Co were mixed to produce a composite magnetic body. The mixing ratio of the B2 powder and the H5 powder was controlled so that the ratio of the Co crystal phase in the mixed powder became the value shown in Table 5. In addition, the production conditions of the composite magnetic body in Samples H6 to H8 were the same as in Experiment 1 except that the mixed powder was used.

[0148] Table 5 shows the evaluation results of Experiment 3. In addition, the evaluation results of Samples A2, B2, B13 and B22 of Experiments 1 to 2 are also shown in Table 5.

[0149] [Table 5]

[0150]

[0151] As shown in Table 5, in the case where the metallic magnetic powder having a single-phase structure was mixed, if the mixing ratio of the B2 powder composed of hcp-Co was increased, although the magnetic loss was reduced to 0.080 or less, the magnetic permeability was reduced to less than 1.15, and the evaluation criteria of the magnetic permeability could not be satisfied (Sample H2 and Sample H6). On the other hand, if the mixing ratio of the Hl powder composed of ε-Co or the H5 powder composed of fcc-Co was increased, although the magnetic permeability became 1.15 or more, the magnetic loss exceeded 0.100, and the evaluation criteria of the magnetic loss could not be satisfied (Samples H3 to H4, H7 to H8). Thus, in the samples in which the metallic magnetic powder having a single-phase structure was mixed, high magnetic permeability and low magnetic loss could not be satisfied at the same time.

[0152] On the contrary, in the examples having a mixed-phase structure (Samples A2, B13 and B22), the magnetic permeability was 1.15 or more and the magnetic loss was 0.100 or less. From the results of Experiments 1 to 3, it was found that by the nanoparticles having a main phase of hcp-Co having a mixed-phase structure including fcc-Co or / and ε-Co, high magnetic permeability and low magnetic loss could be appropriately satisfied at a high frequency band.

[0153] (Experiment 4)

[0154] In Experiment 4, ZnCl2 was added as a raw material of the amphoteric metal, and metallic magnetic powders of Samples El to E6 were produced by the thermal decomposition method in a gas phase. ZnCl2 was added at the start of the reaction, and the amount of ZnCl2 added was controlled so that the ratio of Zn in each sample (W AM / (W Co +W AM) to the values shown in Table 6. In addition, in Experiment 4, the reaction temperature was set to 57°C and the reaction time was set to 3 h so that the average particle diameter (D50) of the nanoparticles became 20 ± 2 nm. The manufacturing conditions other than the above were the same as in Experiment 1, and the magnetic properties of the composite magnetic bodies of Samples E1 to E6 were evaluated. Table 6 shows the evaluation results of Experiment 4.

[0155] [Table 6]

[0156]

[0157] As shown in Table 6, in Samples E1 to E6 in which Zn was added as the amphoteric metal, both high permeability and low magnetic loss at 5 GHz could be achieved. In addition, in the XRD patterns of Samples E1 to E6, it was confirmed that a diffraction peak of Zn was detected, and Zn existed as a metal crystal.

[0158] (Experiment 5)

[0159] In Experiment 5, metal magnetic powders of each sample were manufactured under the conditions shown in Table 7. Specifically, in Experiment 5, ZnCl2 was added at the start of the reaction, and the level of the reaction temperature was changed, and metal magnetic powders in which the ratio of the Co crystal phase was different were manufactured. The reaction time was set to a predetermined time according to the reaction temperature so that the average particle diameter (D50) of the nanoparticles in each sample became 20 ± 2 nm. The manufacturing conditions other than the above were the same as in Experiment 1, and the magnetic properties of the composite magnetic bodies of each sample were measured. Table 7 shows the evaluation results of Experiment 5.

[0160] [Table 7]

[0161]

[0162] In Experiment 2 in which Zn was not added, if the ratio of the secondary phase becomes high, there is a tendency for the magnetic loss to increase, but in the examples of Experiment 5 shown in Table 7, by adding Zn, there is a tendency for the magnetic loss to be reduced compared to Experiment 2 (Tables 2 to 4). From this result, it was found that by adding an amphoteric metal, the magnetic loss at a high frequency band can be further reduced. In addition, in each example of Experiment 5, it was also confirmed that Zn existed as a metal crystal by XRD analysis.

[0163] (Experiment 6)

[0164] In Experiment 6, metal magnetic powders of each sample were manufactured under the conditions shown in Table 8. Specifically, in Experiment 6, ZnCl2 was added at the start of the reaction, and the reaction time was changed, and metal magnetic powders in which the average particle diameter was different were manufactured. The reaction temperature of each sample was set to 57°C. The manufacturing conditions other than the above were the same as in Experiment 1, and the magnetic properties of the composite magnetic bodies of each sample were measured. Table 8 shows the evaluation results of Experiment 6.

[0165] [Table 8]

[0166]

[0167] In Experiment 1 in which Zn was not added, if the average particle diameter of the nanoparticles became large, there was a tendency for the magnetic loss to increase, but in the examples of Experiment 6 shown in Table 8, by adding Zn, there was a tendency for the magnetic loss to be reduced compared to Experiment 1 (Table 1). From the results thereof, it was known that by adding an amphoteric metal, it was possible to further reduce the magnetic loss at high frequencies. Furthermore, in each of the examples of Experiment 6, by analysis by XRD, it was also possible to confirm that Zn was present as a metal crystal.

[0168] (Experiment 7)

[0169] Samples A21, A22 (examples)

[0170] In Samples A21 and A22, after the metal magnetic powder was manufactured under the same conditions as Sample A2 of Experiment 1, the composite magnetic body was manufactured by media dispersion based on a bead mill. In the media dispersion, beads of Zr02having a diameter of 0.2 mm were used. The processing time of the media dispersion in Sample A21 was 10 min, and the processing time of the media dispersion in Sample A22 was 30 min. The manufacturing conditions other than the above were the same as in Experiment 1.

[0171] Samples E11 to E15 (examples)

[0172] In Samples E11 to E15, ZnCl2was added after a prescribed time had elapsed from the start of the reaction. In each of Samples E11 to E15, the reaction temperature was set to 57°C, and the reaction time was set to 3 h. In Samples E11, E13, and E14, ZnCl2was added after 1 h had elapsed from the start of the reaction, and then the reaction was further continued for 2 h. In Samples E12 and E15, ZnCl2was added after 2 h had elapsed from the start of the reaction, and then the reaction was further continued for 1 h.

[0173] In addition, in Samples E11 to E12, the composite magnetic body was manufactured by ultrasonic dispersion, as in Experiment 1 (i.e., the same as Sample E5). On the other hand, in Samples E13 to E15, the composite magnetic body was manufactured by media dispersion based on a bead mill. The processing time of the media dispersion in Sample E13 was 10 min, and the processing time in Samples E14 and E15 was 30 min. The manufacturing conditions other than the above were the same as in Experiment 1.

[0174] Table 9 shows the evaluation results of each example of Experiment 7. In Experiment 7, the cross section of the composite magnetic body was analyzed by using mapping analysis of TEM-EDS, and the presence site of Zn was determined. In the item of "Zn detection site" in Table 9, "Y" is written in the site where the amphoteric metal was detected, and "-" is written in the site where the amphoteric metal was not detected. Further, in each example of Experiment 7, the diffraction peak of Zn was detected in the XRD pattern, and Zn existed as a metal grain.

[0175] [Table 9]

[0176]

[0177] From the results shown in Table 9, it was found that the presence site of the amphoteric metal (Zn) can be controlled depending on the timing of adding the raw material of the amphoteric metal (ZnCl2) and the condition of the dispersion treatment. Further, even in the case where the presence site of the amphoteric metal is changed, high permeability and low magnetic loss can be both satisfied in the high frequency band.

[0178] (Experiment 8)

[0179] In Experiment 8, after the metal magnetic powder was manufactured under the same conditions as those of Sample B23 of Experiment 2, slow oxidation treatment was performed on the metal magnetic powder, and metal magnetic powders of Samples B29 and B30 were obtained. The condition of the slow oxidation treatment was controlled so that the content rate (W%) of Co with respect to 100 wt% of the metal magnetic powder becomes the value shown in Table 10. Further, since the slow oxidation treatment, a part of Co contained in the metal magnetic powder was oxidized, and therefore, the metal magnetic powders of Samples B29 and B30 contain oxygen (O) in addition to Co (main component). Co

[0180] Samples B29 and B30 of Experiment 8 were also manufactured into the composite magnetic body under the same conditions as those of Sample B23 (i.e., the conditions described in Experiment 1), and the magnetic properties thereof were measured. Table 10 shows the evaluation results of Experiment 8. Further, the content rate of Co shown in Table 10 was calculated by analyzing the XRD pattern of the composite magnetic body using X-ray analysis integration software.

[0181] [Table 10]

[0182]

[0183] As shown in Table 10, in Samples B29 and B30 in which the content rate of Co was changed by the slow oxidation treatment, the same effect as that of Sample B23 can also be confirmed, and high permeability at 5 GHz can be ensured and the magnetic loss can be reduced compared with the present (Comparative Example).

[0184] (Experiment 9)

[0185] ​In Experiment 9, after the metal magnetic powder was produced under the same conditions as those of Sample A2 of Experiment 1, the blending ratio of the metal magnetic powder in the composite magnetic body was changed, and the composite magnetic bodies of Samples A201 to A205 were produced. The blending ratio of the metal magnetic powder in each of Samples A201 to A205 was controlled so that the content of the nanoparticles in the composite magnetic body would be the value shown in Table 11. Further, the production conditions other than the blending ratio of the metal magnetic powder were the same as those of Sample A2.

[0186] In addition, in Experiment 9, as comparative examples, the composite magnetic bodies of Samples C261 to C265 were produced. In each of Samples C261 to C265, the metal magnetic powder having ε-Co as the main phase was produced under the same conditions as those of Sample C26 (comparative example) of Experiment 2. Then, the blending ratio of the metal magnetic powder was adjusted so that the content of the nanoparticles in the composite magnetic body would be the value shown in Table 11, and the composite magnetic body was obtained. Further, the production conditions other than the blending ratio of the metal magnetic powder were the same as those of Sample C26.

[0187] Further, in Experiment 9, the cross section of the produced composite magnetic body was observed by TEM, and the area ratio of the metal magnetic powder (nanoparticles) contained in the composite magnetic body was measured. As a result, it was confirmed that in each of the samples of Experiment 9, the area ratio of the nanoparticles agreed with the target value (vol%) shown in Table 11.

[0188] Generally, if the content (filling rate) of the magnetic powder in the composite magnetic body is increased, there is a tendency that although the magnetic permeability rises, the magnetic loss characteristics decrease (i.e., the magnetic loss becomes large). In Experiment 9, considering the change in the magnetic characteristics due to the increase or decrease in the filling rate, the criteria for the magnetic characteristics were set in accordance with the content of the nanoparticles. Specifically, in Experiment 9, the sample satisfying the requirements shown below was judged to be "good".

[0189] Content of nanoparticles 10 vol%: 1.15 < μ', tan δ < 0.100

[0190] Content of nanoparticles 20 vol%: 1.30 < μ', tan δ < 0.150

[0191] Content of nanoparticles 30 vol%: 1.45 < μ', tan δ < 0.200

[0192] Content of nanoparticles 40 vol%: 1.60 < μ', tan δ < 0.250

[0193] Content of nanoparticles 50 vol%: 1.75 < μ', tan δ < 0.300

[0194] Content of nanoparticles 60 vol%: 1.90 < μ', tan δ < 0.350

[0195] Table 11 shows the evaluation results of Experiment 9.

[0196] [Table 11]

[0197]

[0198] From the results shown in Table 11, it is known that in the examples (Samples A201 to A205) in which the content ratio of the nanoparticles in the composite magnetic body was changed, high magnetic permeability μ' could be ensured and the magnetic loss was reduced as compared with the corresponding comparative examples (Samples C261 to C265).

Claims

1. A metallic magnetic powder comprising Co as the main component, wherein, The main component refers to the element that accounts for more than 80 wt% of the metallic magnetic powder. The metallic magnetic powder comprises metallic nanoparticles with an average particle size D50 of 1 nm to 100 nm. The main phase of each of the metal nanoparticles is hcp-Co. The main phase refers to the crystalline phase that occupies more than 50% of the metallic magnetic powder. The metallic magnetic powder contains fcc-Co and / or ε-Co as a secondary phase.

2. The metallic magnetic powder as described in claim 1, wherein, The proportion of hcp-Co in the metallic magnetic powder is set to W. hcp Set the ratio of fcc-Co to W fcc Let the ratio of ε-Co be W. ε , W hcp / (W) hcp +W fcc +W ε The percentage is between 70% and 99%.

3. The metallic magnetic powder as described in claim 1 or 2, wherein, The average particle size D50 of the metal nanoparticles is above 1 nm and below 70 nm.

4. The metallic magnetic powder as described in claim 1 or 2, wherein, The metallic magnetic powder contains Zn. Zn exists on the surface of the nanoparticles and / or inside the nanoparticles.

5. A composite magnetic material comprising the metallic magnetic powder and resin as described in claim 1.

6. The composite magnetic material as described in claim 5, wherein it comprises Zn.

7. An electronic component comprising the metallic magnetic powder of claim 1 or 2.

8. An electronic component comprising the composite magnetic material as described in claim 5 or 6.

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