KR102361011B1 - Method for manufacturing metal powder - Google Patents

Abstract

The oxide can be uniformly coated on the metal particles, preventing the formation of agglomerates of the oxide. In the method for producing a metal powder, by mixing a dispersion containing a metal powder and a metal complex having a ligand, and water containing an acid or an alkali, at least a part of the surface of the metal powder by an oxide generated from the metal complex to cover

Description

Method for manufacturing metal powder

One aspect of the present invention relates to a method for producing a metal powder such as nickel, copper, or silver suitable for various uses such as a conductive paste filler used for electronic parts, a bonding material for titanium materials, and a catalyst, and in particular, an oxide of the metal powder It relates to a method for producing a metal powder suitable for heat treatment by uniformly coating with a

Conductive metal powders, such as Ni, Cu, Ag, are useful for forming an internal electrode of a multilayer ceramic capacitor. In particular, nickel powder has recently attracted attention as such a use. Among them, the ultrafine nickel powder prepared according to the dry manufacturing method is promising for the above use. In such an ultrafine nickel powder, in accordance with the miniaturization and increase in capacity of the capacitor, the ultrafine powder having a particle diameter of 0.5 μm or less and 0.3 μm or less is required, as well as a particle diameter of 1 μm or less, due to the requirements such as thinning and low resistance of the internal electrode. .

In the manufacturing process of a multilayer ceramic capacitor, although there is a process of performing heat treatment to crystallize the dielectric layer, since the sintering temperature of the dielectric layer is higher than the sintering temperature of the nickel powder, the heat treatment becomes an excessive temperature for the nickel powder. In addition, the sintering temperature of the nickel powder tends to decrease due to the ultrafine pulverization of the nickel powder described above. Nickel powder is sintered by heat treatment to cause thermal shrinkage, which causes delamination or cracks in the internal electrodes, thereby deteriorating the performance of the multilayer ceramic capacitor.

For such a problem, a method of suppressing sintering of the metal powder by coating the metal powder with an oxide or the like can be considered. Japanese Patent Laid-Open No. 2000-282102 (Patent Document 1) describes a method of mixing a dielectric material with nickel powder.

Further, Japanese Patent Laid-Open No. 1999-124602 (Patent Document 2) discloses that an oxide or a hydroxide is produced by hydrolysis of a metal salt, and the oxide generated in the liquid is adsorbed to the metal powder.

Japanese Laid-Open Patent Publication No. 2000-282102 (published on October 10, 2000) Japanese Laid-Open Patent Publication No. 1999-124602 (published on May 11, 1999)

However, although the method described in Patent Document 1 is a method of suppressing sintering of metal powder by a dielectric, mixing of the metal powder and dielectric is difficult with atomization of the metal powder, and there is a problem in that the metal powder and the dielectric are separated.

Moreover, in the method of patent document 2, since the hydrolysis rate of a metal salt is fast and the produced|generated oxide forms an aggregate, there exists a problem that a metal powder cannot be coat|covered uniformly.

Accordingly, it is an object of one aspect of the present invention to provide a method for producing an oxide-coated metal powder capable of uniformly coating metal particles with an oxide and preventing the formation of agglomerates of the oxide.

As a result of intensive studies on the coating of metal particles with oxides, the present inventors have found that the surface coverage of oxides can be increased by stabilizing the metal alkoxide with a complexing agent and mixing with water containing an acid or alkali, and the oxide aggregates It has been found that it is possible to prevent this from occurring, resulting in completing one aspect of the present invention.

That is, an aspect of the present invention is a manufacturing method for producing a metal powder in which at least a portion of the surface is coated with an oxide,

At least a part of the surface of the metal powder is coated with an oxide generated from the metal complex by mixing a dispersion containing a metal powder and a metal complex having a ligand represented by Formula 1, and water containing an acid or alkali characterized in that

[Formula 1]

...(식 1)

...(Equation 1)

(Wherein, R ₁ and R ₂ each represent a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and may be the same as or different from each other, and R ₁ and R ₂ may be bonded to each other to form a ring.)

ADVANTAGE OF THE INVENTION According to one aspect|mode of this invention, heat resistance can be improved compared with the prior art at the point which can coat|cover more uniformly than the conventional oxide-coated metal powder, and it can prevent the formation of an aggregate of oxides.

1 is a STEM photograph and EDS mapping image of the SiO ₂ coated nickel powder obtained in Example 1.
2 is a STEM photograph and EDS mapping image of the TiO ₂ coated nickel powder obtained in Example 2.
3 is a STEM photograph and EDS mapping image of the ZrO ₂ coated nickel powder obtained in Example 3.
4 is a STEM photograph and EDS mapping image of the Al ₂ O ₃ coated nickel powder obtained in Example 4.
5 is a STEM photograph and EDS mapping image of the La ₂ O ₃ coated nickel powder obtained in Example 5.
6 is a STEM photograph and EDS mapping image of the TiO ₂ coated nickel powder obtained in Comparative Example.

<Method for producing metal powder>

In the manufacturing method of the metal powder which concerns on this embodiment, the dispersion liquid of a metal powder and the water containing an acid or an alkali are mixed. Here, the dispersion of the metal powder contains a metal alkoxide and a complexing agent. Thereby, at least a part of the surface of a metal particle is coat|covered with the oxide obtained by hydrolyzing a metal alkoxide and the metal complex produced|generated from this metal alkoxide and a complexing agent.

(metal powder)

The metal powder is an aggregate of metal particles, and examples of the metal constituting the metal particles include nickel, copper, silver, aluminum, titanium, iron, cobalt, tungsten and molybdenum, and alloys of these metals. Among these, as for the metal which comprises metal particle|grains, it is more preferable that they are nickel, copper, and silver. These metal powders are suitably used for various uses, such as a paste filler, the composite material of a titanium material, or a catalyst, For example, nickel, copper, silver, etc. are used suitably for a paste filler. The average particle diameter of the metal particles is not particularly limited, but is preferably 1 µm or less, more preferably 0.5 µm or less, still more preferably 0.3 µm or less, still more preferably 0.2 µm or less, still more preferably 0.1 µm or less. The metal powder having such an average particle diameter can be suitably produced by, for example, a gas phase reduction method or a liquid phase reduction method. As such, when the average particle diameter is 1 μm or less, it is also possible to uniformly coat the oxide on the surface of the metal particles produced by the gas phase reduction method or the liquid phase reduction method, one of the advantages of the production method according to the embodiment.

In addition, according to the manufacturing method according to this aspect, a uniform coating is possible even with a metal powder having such a minute average particle diameter, and a metal powder having a 5% shrinkage temperature and a sintering temperature of the metal powder higher than before, that is, a metal powder having high heat resistance. can Accordingly, when the metal powder is used as an internal electrode of the multilayer capacitor, cracks and delamination can be prevented from occurring when the multilayer capacitor is fired. Since the metal powder can be coated uniformly, it is possible to prevent the internal electrode from short-circuiting due to the generation of coarse metal powder as the metal powder is connected and formed into a film. In addition, in this specification, "oxide-coated metal powder" which is a metal powder in which the surface of particle|grains was coat|covered with oxide can be simply called "metal powder" for convenience.

The dispersion for dispersing the metal powder before being coated with the oxide may contain an organic solvent. The organic solvent may be any solvent capable of dissolving the metal alkoxide and the complexing agent, and examples thereof include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, butanol, ethylene glycol and propylene glycol; ethers such as dioxane, tetrahydrofuran, 2-methoxyethanol and diethylene glycol; and aromatic solvents such as toluene and xylene. In addition, as an organic solvent, Ketones, such as acetone, methyl ethyl ketone, and cyclohexane; and esters such as ethyl acetate, isopropyl acetate, and butyl acetate. Especially, since it is easy to handle, it is more preferable that an organic solvent is alcohol.

(metal alkoxide)

The dispersion contains a metal alkoxide. The metal alkoxide produces an oxide while inhibiting hydrolysis by the complexing agent, and this oxide coats the surface of the metal particle.

As a metal alkoxide, the metal alkoxide of Formula 2 shown below can be used preferably, for example.

M(OR ₃ ) _P … (Equation 2)

(Here, M is one metal selected from the group consisting of Si, Ti, Zr, Al, La, Cr and Ba, and R ₃ is a linear alkyl group having 1 to 4 carbon atoms and a branched alkyl group having 3 to 4 carbon atoms, p is determined according to the type of M and is an integer from 2 to 4.)

In the alkoxy group shown in Formula 2, examples of the linear alkyl group represented by R ₃ include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Moreover, in the alkoxy group shown in said Formula 2, an isopropyl group, an isobutyl group, and t-butyl group are mentioned as a C3-C4 branched alkyl group. One type of metal alkoxide can be used and two or more types of things can also be used simultaneously.

In addition, the metal alkoxide forming the metal complex together with the complexing agent is not particularly limited as long as it is hydrolyzed to generate an oxide. For example, a part of the metal alkoxide may be included as an oligomer in the dispersion. Further, although not limited thereto, for example, in the case of using a metal powder as an internal electrode of a multilayer ceramic capacitor, in order to avoid a large amount of carbon atoms remaining in the capacitor, the metal alkoxide may contain an alkyl group and an allyl group bonded to the metal part. It is preferable not to have an organic group. One type of metal alkoxide can be used and two or more types of things can also be used simultaneously. Hereinafter, the metal element (metal part (M)) contained in the metal alkoxide may also be called a coating element. The coating element may be the same type of metal as the metal powder, or may be a different type of metal.

The amount of the metal alkoxide to be blended in the dispersion may be appropriately adjusted depending on the amount of the metal powder dispersed in the organic solvent and the particle size of the metal powder. As weight%, it is preferable that it is an amount of 0.5 weight% or more and 5 weight% or less with respect to this metal powder. Accordingly, a metal powder having a surface coverage of 80% or more and 100% or less of the metal particles by the oxide can be suitably produced.

(complexing agent)

A complexing agent slows the hydrolysis rate of a metal alkoxide by forming a metal complex with the metal part of a metal alkoxide. Accordingly, it is possible to make fine particles of the oxide generated by the metal alkoxide and the metal complex generated from the metal alkoxide. Therefore, the oxide can be uniformly attached to the surface of the metal particles.

As the complexing agent, any one capable of coordinating to the metal moiety of the metal alkoxide may be used, and typically β-diketone represented by the following formula (1) can be used.

(Wherein, R ₁ and R ₂ each represent a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and may be the same as or different from each other, and R ₁ and R ₂ may be bonded to each other to form a ring.)

Preferred groups as R ₁ and R ₂ in Formula 1 are, for example, a hydrogen atom, a linear alkyl group having 1 to 5 carbon atoms, and a branched alkyl group having 3 to 5 carbon atoms. When R ₁ and R ₂ are the groups listed above, the rate of hydrolysis of the metal alkoxide can be preferably slowed down.

Examples of the linear alkyl group having 1 to 5 carbon atoms for R ₁ and R ₂ include a methyl group, an ethyl group, n-propyl group, n-butyl group and n-pentyl group.

Examples of the branched alkyl group having 3 to 5 carbon atoms for R ₁ and R ₂ include isopropyl group, isobutyl group, t-butyl group, isopentyl group and neopentyl group.

Among the above-mentioned complexing agents, from the viewpoint of solubility in water added for hydrolysis, when R ₁ and R ₂ are a linear alkyl group, it preferably has 1 to 3 carbon atoms, and in the case of a branched alkyl group, it preferably has 3 carbon atoms, More preferably, the complexing agent is acetylacetone.

It is also possible to control the hydrolysis rate by changing the mixing ratio of the metal alkoxide and the complexing agent. Although the addition amount of a complexing agent is not limited, It is preferable to make it 1 to 3 times mole with respect to the total number of moles of the added metal alkoxide. When the addition amount of a complexing agent exists in said range, the rate of hydrolysis of a metal alkoxide is optimized. Therefore, the growth of the oxide does not occur rapidly, and the formation of an agglomerate of the oxide is suppressed. Thereby, a fine oxide is formed and coat|covers a metal particle, and uniform coating|cover of a metal particle can be implement|achieved.

(metal complex)

A metal complex is a metal complex which forms an oxide upon hydrolysis, More specifically, the metal complex can take the structure shown, for example by Formula 3 or Formula 4 below.

M ₁ (OR ₃ ) _q X _r … (Equation 3)

(Here, M ₁ is one metal selected from the group consisting of Si, Ti, and Zr, X is a ligand shown in Formula 1 above, r is 4 when q is 0, and r when q is 2 is 2.)

M ₂ X _S … (Equation 4)

(Here, M2 is one metal selected from the group consisting of Al, La, Cr, and Ba, X is a ligand shown in Formula 1 above, s is determined depending on the type of M2, and is ₂ or 3. )

In addition, the metal complex as shown in Formula 3 or Formula 4 is formed to be bonded as a result of coordination of the complexing agent to the metal moiety of the metal alkoxide, for example. In addition, in the manufacturing method according to an aspect, if it is a metal complex as shown in Formula 3 or Formula 4 above, instead of generating a metal complex from a metal alkoxide, the above Formula 3 or Formula 4 prepared by another method in advance A metal complex can also be mix|blended with a dispersion liquid.

(water containing acid or alkali)

By mixing water containing an acid or an alkali with the mixed solution of the metal powder and the metal complex, the metal compound is hydrolyzed to form an oxide. In water, the pH is adjusted so that the surface charge of the metal powder is opposite to the surface charge of the oxide generated by hydrolysis of the metal compound by acid or alkali. The water which adjusted pH in this way is also called pH-adjusted water hereafter. When added to a dispersion of a metal powder and a metal complex, the oxide can have a surface charge opposite to that of the metal powder, so that the oxide can be uniformly coated on the metal powder by electrostatic attraction.

The amount of the pH-adjusting water to be mixed with the dispersion may be greater than or equal to the amount capable of completely hydrolyzing the metal alkoxide and the metal complex. In addition, the temperature at the time of mixing the dispersion and the pH-adjusting water may be equal to or higher than the freezing point of the mixed solution of the dispersion and the pH-adjusting water, and is preferably 0 to 25°C.

The order of mixing the pH-adjusting water to the dispersion consisting of the metal powder, the metal alkoxide, and the complexing agent is both a method of adding the pH-adjusting water to the dispersion and a method of adding the dispersion to the pH-adjusting water, but adding the pH-adjusting water to the dispersion The method is more preferable because it can coat the metal particles more uniformly with the oxide.

As the acid or alkali added to control the pH in the pH-adjusted water, any acid or alkali can be used as long as the pH can be adjusted. , When using an alkali, aqueous ammonia, sodium hydroxide, etc. are preferable.

The obtained metal powder is made into a product through filtration, washing, and drying. As a method of filtration, washing|cleaning, and drying, a well-known method can be used, For example, filtration can be performed by reduced pressure filtration, pressure filtration, etc., and drying can use a box-type dryer, an airflow dryer, etc.

Hereinafter, preferred embodiments of the present invention will be described in detail.

<Production example of oxide-coated nickel powder>

Hereinafter, it demonstrates in detail based on the manufacturing example of oxide-coated nickel powder. Meanwhile, the metal powder that can be coated according to the method for manufacturing the metal powder according to the present embodiment is not limited to nickel.

First, the nickel powder is dispersed in an organic solvent to make the nickel powder into a slurry. Although nickel powder obtained by methods, such as a liquid phase reduction method and a gas phase reduction method, can be used as nickel powder, From viewpoints, such as uniformity of particle size distribution, the nickel powder obtained by the gas phase reduction method is preferable. Meanwhile, the nickel powder may have an average particle diameter of 0.03 μm to 1.0 μm, and a CV value of a particle size distribution of 50% or less. On the other hand, the average particle diameter of the nickel powder is obtained by taking a photograph of the particles of the nickel powder before coating with a scanning electron microscope, and measuring the particle size of 500 or more nickel powders from the photograph using image analysis software, and the particle size distribution of the obtained nickel powder The number average particle diameter was calculated from . In this case, the particle diameter is the diameter of the minimum circle surrounding the particle. In addition, the CV value of a particle size distribution points out the standard deviation/number average particle diameter of a particle size distribution.

Next, a solution in which the metal alkoxide and the complexing agent are dissolved is added to the slurry of the metal powder. The metal alkoxide used in this case may be the metal alkoxide shown above. As the complexing agent, any one capable of coordinating with the metal moiety of the metal alkoxide may be used. For example, β-diketone represented by the above formula (1) can be used. On the other hand, in the step before mixing with the pH-adjusted water, for example, it is preferable to sufficiently disperse the metallic nickel powder by stirring the dispersion.

Next, to the dispersion containing the metal powder, metal alkoxide, and complexing agent, water whose pH is controlled with acid or alkali is added at once so that the surface charge of the metal powder and the surface charge of the oxide generated from the metal alkoxide are opposite. and stirring to hydrolyze the metal alkoxide and form an oxide.

At this time, the pH of the water to be added is pH 1.5 to 14 when coated with SiO ₂ , pH 6 to 10 when coated with TiO ₂ , pH 9 to 10 when coated with ZrO ₂ , Al ₂ O ₃ In the case of coating with pH 8-11, and La ₂ O ₃ , pH 1.5-10 is preferable. When the pH is within the above range in each case, the coating can be more uniformly performed.

The generated oxide is adsorbed to the surface of the metal particle by electrostatic attraction because the surface charge is opposite to that of the metal powder. In addition, the particle size of the oxide formed from the metal alkoxide and the metal complex is small, and is uniformly adsorbed on the surface of the metal particle. As the acid and alkali added to control the pH of water, any acid or alkali can be used as long as the pH can be adjusted. desirable.

The obtained oxide-coated metal powder is made into a product through filtration, washing, and drying.

The present invention is not limited to each of the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in other embodiments are also included in the technical scope of the present invention. .

Examples are shown below, and embodiments of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail.

Example

An oxide-coated metal powder was prepared. Hereinafter, it will be described in detail.

[Assessment Methods]

The nickel powder produced by an aspect of the present invention was evaluated for quality by the shape and thickness of the oxide film, chemical state, and thermal shrinkage. Next, each evaluation method is demonstrated.

[Average particle size]

The average particle diameter of the metal powder is obtained by taking a photograph of the particles of the metal powder with a scanning electron microscope (manufactured by Nippon Electronics Co., Ltd., trade name JSM-7800F), and from the photograph, the particle diameter of about 1,000 particles is calculated using image analysis software (Mountech Corporation). Article, trade name MacView 4.0) was used, and the average value was calculated. On the other hand, the particle diameter was set as the diameter of the minimum circle surrounding the particles.

[Shape of oxide film and film thickness]

The obtained oxide-coated nickel powder was sprinkled on a carbon supporting membrane, and a photo of the nickel powder was taken with a scanning transmission electron microscope (STEM) at a magnification of 1 million to 1.5 million times, and low power field imaging was performed. In addition, elemental mapping was performed by an EDS (Energy Dispersive X-ray Spectrometry) detector equipped with a scanning transmission electron microscope.

[Chemical state]

The obtained oxide-film nickel powder was fixed to an indium plate (thickness 0.5 mm), and nickel and a coating element were measured with the photoelectron spectrometer (Thermo Fisher Scientific company make, k-alpha+).

[Heat Shrinkage Rate]

After adding camphor at 3 wt% to the obtained oxide-coated nickel powder, the camphor was dissolved with acetone and stirred until the acetone evaporated. The mixed powder of oxide-coated nickel powder and camphor was press-molded into pellets having a diameter of 5 mm and a height of 2 mm.

Thermal shrinkage was measured with a thermomechanical analysis apparatus (TMA). Measurement conditions were a temperature range: room temperature to 1350°C, a temperature increase rate: 5°C/min, and an atmosphere: 2% H ₂ , 98% N ₂ 300 mL/min. The temperature when the shrinkage rate became 5% was set as the 5% shrinkage temperature.

[Surface Coverage]

On the STEM-EDS mapping, the length of the arc of the region in which no element was detected on the periphery of the metal particle was measured, and the surface coverage was calculated by the following equation.

Surface coverage [%] = (L ₀ -L ₁ )/L ₀ ×100

L ₀ : perimeter of the metal particle

L ₁ : The arc length of the region where no element is detected on the perimeter of the metal particle.

[Example 1]

First, a metallic nickel powder (average particle diameter of 100 nm) was produced according to the method described in JP-A-10-219313. Ethanol was added to this metallic nickel powder to make a 10 wt% slurry. On the other hand, separately from this slurry, when the metallic nickel powder contained in the slurry was 100% by weight, tetraethylorthosilicate (hereinafter also referred to as TEOS) was dissolved in ethanol in an amount corresponding to 2% by weight. Further, as a complexing agent, acetylacetone was added so as to be twice the mole of the Si element. The metallic nickel powder slurry, TEOS, and the ethanol solution of acetylacetone were mixed, stirred for 1 hour, and 200 mL of dispersion liquids containing nickel powder were prepared. Then, 100 mL of water whose pH was adjusted to 8-9 with ammonia water was added at once, and it stirred for 2 hours. Then, _the target SiO2 coating nickel powder was obtained by performing suction filtration and drying at 120 degreeC in air|atmosphere for 1 hour. The STEM photograph and STEM-EDS mapping image of the nickel powder obtained in Example 1 are shown in FIG. In addition, the surface coverage and 5% shrinkage temperature are shown in Table 1.

[Example 2]

Titanium tetraisopropoxide as a metal alkoxide, except having made the addition amount the same as the volume of ₂ wt% SiO2, the same process as Example 1 was performed, and TiO2 _- coated nickel powder was obtained. The STEM photograph and STEM-EDS mapping image of the obtained nickel powder are shown in FIG. In addition, the surface coverage and 5% shrinkage temperature are shown in Table 1.

[Example 3]

The process similar to Example 1 was performed except having made zirconium tetraisopropoxide and the addition amount the same as the volume of ₂ wt% SiO2 as a metal alkoxide, and ZrO2 _- coated nickel powder was obtained. The STEM photograph and STEM-EDS mapping image of the obtained nickel powder are shown in FIG. In addition, the surface coverage and 5% shrinkage temperature are shown in Table 1.

[Example 4]

Aluminum tri-n-butoxide as a metal alkoxide, except having made the addition amount equal to the volume of ₂ wt% SiO2, _it carried out similarly to Example ₁ , and obtained Al2O3 coated nickel powder. The STEM photograph and STEM-EDS mapping image of the obtained nickel powder are shown in FIG. In addition, the surface coverage and 5% shrinkage temperature are shown in Table 1.

[Example 5]

Lanthanum triisopropoxide as the metal alkoxide, 2-propanol as the organic solvent, and the addition amount being equal to the volume of 2 wt% SiO ₂ by the same treatment as in Example 1, La ₂ O ₃ coated nickel powder got The STEM photograph and STEM-EDS mapping image of the obtained nickel powder are shown in FIG. In addition, the surface coverage and 5% shrinkage temperature are shown in Table 1.

[Comparative example]

The same treatment as in Example 2 was performed except that acetylacetone was not added to obtain a TiO ₂ coating nickel powder. The STEM photograph and STEM-EDS mapping image of the obtained nickel powder are shown in FIG. In addition, the surface coverage and 5% shrinkage temperature are shown in Table 1.

[Reference example]

The metallic nickel powder obtained similarly to Example 1 was used as a reference example, without coat|covering with a coating element.

According to Table 1, it can be seen that in Example 2, the surface coverage was improved compared to the comparative example, and the coverage was improved by the complexing agent. In addition, in each Example, the surface coverage is 80% or more, and as can be seen from FIG. 1 , it can be seen that the coating is uniformly compared to the comparative example. Compared with the Reference Example and the Comparative Example, it can be seen that the 5% shrinkage temperature is increased in each Example.

The present invention can be used as an internal electrode of a multilayer ceramic capacitor.

Claims (5)

A method for producing a metal powder having at least a portion of its surface coated with an oxide, the method comprising:
At least a part of the surface of the metal powder is coated with an oxide generated from the metal complex by mixing a dispersion containing a metal powder and a metal complex having a ligand represented by Formula 1, and water containing an acid or alkali Method for producing a metal powder, characterized in that.
[Formula 1]

...(Equation 1)
(Wherein, R ₁ and R ₂ each represent a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and may be the same as or different from each other, and R ₁ and R ₂ may be bonded to each other to form a ring.) According to claim 1,
The method for producing a metal powder, characterized in that the dispersion contains a metal alkoxide. 3. The method of claim 2,
and a step of producing the metal complex by mixing the metal alkoxide and the complexing agent serving as the ligand. 4. The method according to any one of claims 1 to 3,
The method for producing a metal powder, characterized in that the ligand is acetylacetone. According to claim 1,
A method for producing a metal powder, characterized in that the surface coverage by the oxide is 80% or more.

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