WO2024070098A1 - Particules de nickel et procédé de fabrication de particules de nickel - Google Patents

Particules de nickel et procédé de fabrication de particules de nickel Download PDF

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Publication number
WO2024070098A1
WO2024070098A1 PCT/JP2023/023990 JP2023023990W WO2024070098A1 WO 2024070098 A1 WO2024070098 A1 WO 2024070098A1 JP 2023023990 W JP2023023990 W JP 2023023990W WO 2024070098 A1 WO2024070098 A1 WO 2024070098A1
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Prior art keywords
nickel
particles
metal element
less
mass
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PCT/JP2023/023990
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English (en)
Japanese (ja)
Inventor
光彦 西野
隆史 佐々木
裕樹 澤本
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三井金属鉱業株式会社
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Priority to JP2023542724A priority Critical patent/JP7340728B1/ja
Publication of WO2024070098A1 publication Critical patent/WO2024070098A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/052—Metallic powder characterised by the size or surface area of the particles characterised by a mixture of particles of different sizes or by the particle size distribution
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/17—Metallic particles coated with metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/30—Making metallic powder or suspensions thereof using chemical processes with decomposition of metal compounds, e.g. by pyrolysis
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form

Definitions

  • the present invention relates to nickel particles and a method for producing the same.
  • Nickel particles are generally used to form the internal electrodes of multilayer ceramic capacitors (hereafter referred to as "MLCCs") used in electronic devices.
  • MLCCs multilayer ceramic capacitors
  • defects can occur in the internal electrodes due to differences in the sintering temperatures of the raw materials.
  • Patent Document 1 discloses a technology in which nickel powder containing tin or bismuth obtained by the PVD or CVD method is used to form the internal electrodes of an MLCC.
  • the document states that adding a non-magnetic metal such as tin to nickel powder distorts the crystal structure of the nickel, thereby increasing the sintering temperature of the nickel powder.
  • Patent Document 2 discloses a technique for using nickel powder, which has a roughly spherical particle shape and is surface-treated with tin, to form the internal electrodes of an MLCC. The same document also discloses that surface treatment is performed using bismuth in addition to tin. The same document also describes that the sintering behavior is improved by using the nickel powder described in the document.
  • an object of the present invention is to provide nickel particles that have high sintering resistance without excessively increasing electrical resistance.
  • the present invention relates to a nickel particle having a surface region comprising an alloy of nickel and a metallic element M,
  • the metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
  • the content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
  • a region from the outermost surface to a sputtering depth of 5 nm in terms of SiO2 in the depth direction of the nickel particle is measured by X-ray photoelectron spectroscopy
  • the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in the region is defined as X (at%)
  • the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at %)
  • the present invention provides nickel particles having a value of X/Y of
  • the present invention also provides a method for producing nickel particles by heating a mixed liquid containing nickel hydroxide particles, a polyol, polyvinylpyrrolidone, and polyethyleneimine, comprising the steps of: Polyvinylpyrrolidone is used in an amount of 30 parts by mass or more and 200 parts by mass or less per part by mass of polyethyleneimine, The heating reduces the nickel hydroxide particles to nickel base particles,
  • a method for producing nickel particles comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles,
  • the metal element M is at least one element selected from the group consisting of bismuth, copper, iron and molybdenum.
  • the nickel particles of the present invention have a nickel base particle and a surface region containing an alloy of nickel and metal element M (hereinafter also referred to as “nickel-metal M alloy") located on the surface of the base particle.
  • nickel base particle refers to a particle that is substantially composed of nickel element, with the remainder containing unavoidable elements.
  • unavoidable elements include oxygen element and carbon element derived from oxygen and carbon dioxide in the air, and nitrogen element that may be mixed in during the manufacturing process of the nickel particles.
  • nickel-metal M alloy refers to a nickel-based alloy containing the metal element M described below.
  • the nickel-metal M alloy is substantially composed of an alloy of nickel element and metal element M, and contains inevitable elements as the remainder.
  • the metal element M may be present in part in the state of the metal element M alone (i.e., in the state of metal).
  • the metal element M may be present in part in the state of a compound of the metal element M.
  • the metal element M may be present in a state of a combination of two or more of these.
  • the metal element M When the metal element M is present in the surface region containing the nickel-metal M alloy in the state of a compound of the metal element M, examples of the compound include, but are not limited to, oxides, hydroxides, sulfides, sulfates, borides, phosphides, etc. containing the metal M. However, it is desirable that the metal element M in the surface region containing the nickel-metal M alloy is substantially composed of only an alloy with nickel, from the viewpoint of maximizing the inherent advantages of the nickel particles of the present invention.
  • the metal element M in the nickel particles is preferably at least one selected from bismuth, copper, iron and molybdenum.
  • the metal element M is bismuth, copper, iron or molybdenum, the sintering resistance of the nickel particles can be further improved without excessively increasing the electrical resistance of the nickel particles.
  • the metal element M may be only one of bismuth, copper, iron and molybdenum, or any combination of two or more of them. In the following description, when the metal element M (or metal M) is mentioned, it means bismuth, copper, iron or molybdenum, or any combination of two or more of them, depending on the context.
  • the nickel particles contain nickel-metal M alloy in their surface region can be confirmed by the following method. Specifically, first, it is confirmed by X-ray photoelectron spectroscopy (hereinafter also referred to as "XPS") that the nickel particles contain the metal element M in their surface region and that the metal element M is mainly in a metallic state. Next, it is confirmed that the a-axis length in the X-ray diffraction peak of the nickel particles is longer than the a-axis length in the X-ray diffraction peak obtained by measuring only the nickel particles in advance. The extension of the a-axis length in the X-ray diffraction peak means that the substance is in a solid solution.
  • XPS X-ray photoelectron spectroscopy
  • the metal element M confirmed by the XPS measurement exists in a metallic state in the surface region of the nickel particles, and the metal element M and nickel are in a solid solution confirmed by comparing the a-axis lengths, it can be confirmed that the nickel particles contain a nickel-metal M alloy in their surface region.
  • the proportion of the metal element M in the surface region of the nickel particles can be measured by XPS.
  • this region is also referred to as the "particle surface region"
  • the value of X which is the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M, is 0.5 at% or more in the particle surface region.
  • the "maximum value” refers to the maximum value of the value of X when multiple values of X measured along the thickness direction of the particle surface region are different.
  • the metal element M exists so as to have a portion where the value of X is 0.5 at% or more from the viewpoint of further increasing the sintering resistance of the nickel particles described later.
  • the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 3 at% or more, even more preferably 7 at% or more, and particularly preferably 14 at% or more.
  • the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 30 at% or less, even more preferably 20 at% or less, and particularly preferably 15 at% or less.
  • the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 4 at% or more, even more preferably 8 at% or more, and particularly preferably 12 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 20 at% or less, and even more preferably 14 at% or less.
  • the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 4 at% or more, and even more preferably 7 at% or more.
  • the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 30 at% or less, even more preferably 20 at% or less, and particularly preferably 9 at% or less.
  • the value of X (at%) is more preferably 1 at% or more, further preferably 2 at% or more, even more preferably 4 at% or more, and even more preferably 8 at% or more.
  • the value of X (at%) is more preferably 70 at% or less, further preferably 35 at% or less, even more preferably 30 at% or less, and even more preferably 10 at% or less.
  • outermost surface of nickel particles refers to the outermost surface of nickel particles containing a surface treatment agent such as an organic acid or amine when the surface of the nickel particles is present.
  • a surface treatment agent such as an organic acid or amine
  • the nickel particles preferably contain 0.09% by mass or more and 15.8% by mass or less of the metal element M relative to the entire nickel particles.
  • the content of the metal element M relative to the nickel particles is within this range, the sintering resistance can be further improved without excessively increasing the electrical resistance of the nickel particles.
  • the metal element M is bismuth, from the same viewpoint as above, the content of the bismuth element relative to the entire nickel particle is more preferably 0.3 mass% or more, even more preferably 0.4 mass% or more, even more preferably 1 mass% or more, and even more preferably 6.7 mass% or more.
  • the content of the bismuth element relative to the entire nickel particle is more preferably 15.8 mass% or less, even more preferably 13 mass% or less, even more preferably 11.4 mass% or less, and even more preferably 10 mass% or less.
  • the metal element M is copper
  • the content of copper element with respect to the whole nickel particle is more preferably 0.4 mass% or more, more preferably 1 mass% or more, even more preferably 2.1 mass% or more, and even more preferably 4.3 mass% or more.
  • the content of copper element with respect to the whole nickel particle is more preferably 11.4 mass% or less, even more preferably 7.6 mass% or less, even more preferably 6.5 mass% or less, even more preferably 6 mass% or less, and particularly preferably 5.4 mass% or less.
  • the metal element M is iron
  • the content of the iron element relative to the entire nickel particle is more preferably 0.09% by mass or more, even more preferably 0.28% by mass or more, even more preferably 0.40% by mass or more, and even more preferably 0.47% by mass or more.
  • the content of the iron element relative to the entire nickel particle is more preferably 11.4% by mass or less, even more preferably 6% by mass or less, even more preferably 2.87% by mass or less, even more preferably 1.91% by mass or less, and particularly preferably 0.96% by mass or less.
  • the metal element M is molybdenum
  • the molybdenum element content relative to the whole nickel particle is more preferably 0.4 mass% or more, more preferably 1 mass% or more, even more preferably 1.1 mass% or more, and even more preferably 1.6 mass% or more.
  • the molybdenum element content relative to the whole nickel particle is more preferably 11.4 mass% or less, even more preferably 6.4 mass% or less, even more preferably 6 mass% or less, even more preferably 4.9 mass% or less, and particularly preferably 3.3 mass% or less.
  • the content of the metal element M relative to the entire nickel particles can be measured by ICP emission spectrometry, which will be described later.
  • the content of the metal element M in the entire nickel particle satisfies the above-mentioned range, and the value of Y (at%), which is the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M, is preferably 0.1 at% or more and 7 at% or less in the entire nickel particle. It is preferable that the metal element M is present so that the value of Y is within this range, from the viewpoint of further increasing the sintering resistance without excessively increasing the electrical resistance of the nickel particle.
  • the value of Y is more preferably 0.1 at% or more, even more preferably 0.2 at% or more, even more preferably 0.3 at% or more, even more preferably 0.5 at% or more, and particularly preferably 2 at% or more. Also, the value of Y is more preferably 6 at% or less, even more preferably 5 at% or less, even more preferably 4 at% or less, and even more preferably 3 at% or less.
  • the value of Y is more preferably 0.2 at% or more, even more preferably 0.5 at% or more, even more preferably 1 at% or more, even more preferably 2 at% or more, and particularly preferably 4 at% or more. Also, the value of Y is more preferably 7 at% or less, even more preferably 6 at% or less, and even more preferably 5 at% or less.
  • the value of Y is more preferably 0.1 at% or more, even more preferably 0.2 at% or more, even more preferably 0.3 at% or more, and even more preferably 0.5 at% or more.
  • the value of Y is more preferably 6 at% or less, even more preferably 3 at% or less, even more preferably 2 at% or less, and even more preferably 1 at% or less.
  • the value of Y is more preferably 0.2 at% or more, even more preferably 0.3 at% or more, even more preferably 0.5 at% or more, even more preferably 0.7 at% or more, and particularly preferably 1 at% or more.
  • the value of Y is more preferably 6 at% or less, even more preferably 4 at% or less, even more preferably 3 at% or less, and even more preferably 2 at% or less.
  • the value of Y which is the ratio of the number of atoms of the metal element M contained in the entire nickel particle, is measured by ICP atomic emission spectroscopy. Specifically, first, the entire nickel particle is measured by ICP atomic emission spectroscopy to determine the content ratio of the nickel element and the content ratio of the metal element M. Next, the content ratio of the nickel element (mass%) is divided by the atomic weight of the nickel element (58.7) to convert the content ratio to the atomic number A Ni of the nickel element.
  • the content ratio of the metal element M (mass%) is divided by the atomic weight of the metal element M (bismuth is 209, copper is 63.6, iron is 55.9, and molybdenum is 96) to convert the content ratio to the atomic number A M of the metal element M. Then, the ratio of the number of atoms of the metal element M to the atomic number A Ni of the nickel element and the atomic number A M of the metal element M (A M / (A Ni +A M ) ⁇ 100) is calculated to obtain the value of Y.
  • the relationship between the value of X and the value of Y affects the sintering resistance of nickel particles.
  • the temperature at which the nickel particles start to shrink due to sintering increases, that is, the sintering resistance increases.
  • the temperature at which the internal electrodes shrink due to sintering of the nickel particles in the firing process which is one of the manufacturing processes, can be made as close as possible to the temperature at which the dielectric layer shrinks due to sintering of the dielectric particles.
  • Reducing the difference in temperature at which the internal electrodes and the dielectric layer shrink is advantageous because the time at which the internal electrodes and the dielectric layer shrink overlap during the temperature rise process in the firing process. Specifically, it is advantageous from the viewpoint of effectively preventing the occurrence of structural defects such as cracks and delamination (interlayer peeling at the interface between the internal electrodes and the dielectric layers) caused by the difference in temperature and shrinkage rate at which the internal electrodes and the dielectric layers shrink in the firing process of the MLCC.
  • the value of X/Y in the nickel particles is more preferably 1.5 or more, even more preferably 3.7 or more, even more preferably 4 or more, even more preferably 5 or more, and particularly preferably 7 or more.
  • the value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 25 or less, and even more preferably 20 or less.
  • the value of X/Y in the nickel particles is more preferably 0.5 or more, even more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more.
  • the value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 15 or less, even more preferably 13 or less, even more preferably 10 or less, particularly preferably 7 or less, and especially preferably 3 or less.
  • the value of X/Y in the nickel particles is more preferably 1 or more, even more preferably 1.5 or more, even more preferably 3.7 or more, even more preferably 5 or more, and particularly preferably 10 or more.
  • the value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 25 or less, even more preferably 20 or less, and even more preferably 15 or less, from the viewpoint of making the above-mentioned advantages more prominent.
  • the value of X/Y in the nickel particles is more preferably 1 or more, even more preferably 1.5 or more, even more preferably 3 or more, even more preferably 3.7 or more, and particularly preferably 5 or more.
  • the value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 15 or less, even more preferably 13 or less, even more preferably 10 or less, and particularly preferably 7 or less.
  • the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M may be constant in the depth direction or may vary.
  • the value of the ratio may decrease continuously or stepwise from the surface of the nickel particle toward the center.
  • the value of the ratio gradually decreases from the outermost surface to a sputtering depth of 20 nm, since this further improves the sintering resistance of the nickel particle.
  • the value of X/X1 is 0.1 or more and 15 or less in terms of further improving the sintering resistance of the nickel particle.
  • the value of X/X1 is more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more.
  • the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 4 or less, particularly preferably 3 or less, and especially preferably 2.5 or less.
  • the value of X/X1 is more preferably 0.1 or more, even more preferably 0.5 or more, and even more preferably 1 or more.
  • the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 3 or less.
  • the value of X/X1 is more preferably 0.1 or more, even more preferably 0.5 or more, and even more preferably 1 or more. Moreover, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 2 or less. When the metal element M is molybdenum, from the same viewpoint as above, the value of X/X1 is more preferably 0.1 or more, even more preferably 1 or more, and even more preferably 2 or more.
  • the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 3 or less.
  • the method for measuring X1 will be explained in the Examples below.
  • the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1.7 or more, particularly preferably 2 or more, and especially preferably 5 or more.
  • the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, and even more preferably 7 or less.
  • the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, even more preferably 3 or more, and even more particularly preferably 5 or more.
  • the value of X1 itself is more preferably 20 or less, even more preferably 15 or less, and even more preferably 10 or less.
  • the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, even more preferably 2 or more, and even more particularly preferably 4 or more.
  • the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, and even more preferably 6 or less.
  • the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, especially preferably 2 or more, and especially especially preferably 4 or more.
  • the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, even more preferably 6 or less, and even more preferably 5 or less.
  • the nickel particles of the present invention preferably have a value of D50 , which is the number-cumulative particle diameter at 50% of the cumulative number, of 20 nm or more and 200 nm or less.
  • D50 is the number-cumulative particle diameter at 50% of the cumulative number, of 20 nm or more and 200 nm or less.
  • the nickel particles of the present invention are preferably fine particles.
  • the nickel particles of the present invention have a particle diameter D50 within this range, there is an advantage that when the nickel particles of the present invention are used in various applications, for example, as internal electrodes of MLCCs, short circuits between the internal electrodes are less likely to occur.
  • the particle diameter D50 of the nickel particles is more preferably 20 nm or more and 150 nm or less, even more preferably 40 nm or more and 150 nm or less, and even more preferably 40 nm or more and 100 nm or less.
  • the particle diameter D50 of the nickel particles is measured by observing the nickel particles with a scanning electron microscope (SEM). In detail, the nickel particles are photographed with a SEM at a magnification of 50,000 times, and the area of the photographed nickel particles is calculated. The circle equivalent diameter is calculated from the area. The particle size distribution is calculated based on the calculated circle equivalent diameter.
  • the particle size distribution is plotted on the horizontal axis of the graph representing the equivalent circle diameter and on the vertical axis representing the number frequency.
  • the number-cumulative particle size at 50% by number of cumulative particles is defined as D50 .
  • the circle equivalent diameter is determined for 5,000 or more nickel particles.
  • the circle equivalent diameter is calculated using image analysis particle size distribution measurement software (Mac-View, manufactured by Mountec Co., Ltd.).
  • the smallest unit of nickel particle to be observed is determined by whether or not a particle interface that can be recognized as an independent particle is observed using SEM. Therefore, even if an agglomerate consisting of multiple particles is observed, if a particle interface is observed in the agglomerate, the area defined by the particle interface is recognized as a single particle.
  • the nickel particles of the present invention preferably have a small proportion of coarse particles.
  • the proportion of particles having a particle size of 1.5 times or more of D50 (hereinafter also referred to as "coarse particle proportion") is preferably 0.5% by number or less, more preferably 0.3% by number or less, and even more preferably 0.1% by number or less.
  • the nickel particles of the present invention are preferably fine particles, have a low proportion of coarse particles, and have a particle size as uniform as possible. In other words, it is preferable that the particle size distribution curve is sharp.
  • the sharpness of the particle size distribution curve can be evaluated by the coefficient of variation of the particle size.
  • the coefficient of variation is a value defined as ( ⁇ /D 50 ) ⁇ 100(%), where ⁇ (nm) is the standard deviation of the particle size in the particle size distribution.
  • the value of the coefficient of variation is preferably 14% or less, from the viewpoint of reducing the surface roughness of the conductive film formed from the nickel particles.
  • the coefficient of variation is more preferably 13% or less, and even more preferably 12% or less.
  • a coefficient of variation as low as about 8% can reduce the surface roughness of the conductive film to a sufficiently satisfactory degree.
  • the nickel particles of the present invention preferably have high nickel crystallinity.
  • High nickel crystallinity means that the temperature at which the nickel particles of the present invention begin to shrink due to sintering increases.
  • high nickel crystallinity means that the nickel particles have high sintering resistance, as described above.
  • the crystallinity of nickel is often evaluated by Cs/D 50 , which is the ratio of the crystallite size Cs (nm) to the particle size D 50 (nm). The larger the Cs/D 50 value, the higher the crystallinity of the nickel can be evaluated.
  • the Cs/D 50 value is preferably 0.3 or more, more preferably 0.34 or more, and even more preferably 0.37 or more.
  • the larger the Cs/D 50 value the higher the temperature at which nickel particles begin to sinter and shrink.
  • the Cs/D 50 value is preferably 0.6 or less, the temperature can be made sufficiently high, and from this viewpoint, the Cs/D 50 value is more preferably 0.55 or less, and even more preferably 0.52 or less.
  • the value of the crystallite size Cs itself is preferably 15 nm or more and 70 nm or less, more preferably 18 nm or more and 70 nm or less, and even more preferably 20 nm or more and 70 nm or less, from the viewpoint of sufficiently raising the temperature at which the nickel particles sinter and begin to shrink.
  • the crystallite size in this specification refers to the value measured by the WPPF (whole powder pattern fitting) method.
  • WPPF whole powder pattern fitting
  • the Scherrer method is also known as a method for measuring crystallite size, and when the degree of distortion of the crystal is large, the value of the crystallite size obtained based on the Scherrer method is unreliable, so the WPPF method, which is less likely to cause such a problem, is adopted in the present invention. Details of the method for measuring the nickel crystallite size based on the WPPF method will be described in the Examples below.
  • the nickel particles of the present invention preferably do not excessively increase electrical resistance.
  • the performance of the MLCC can be further improved. Therefore, in order to prevent excessive increase in electrical resistance, it is preferable to control the crystal structure of the nickel particles so that the pure nickel component is increased in the nickel particles having a surface region containing nickel-metal M alloy.
  • the a-axis length of the crystal lattice in the nickel crystal structure is preferably 3.520 ⁇ or more and 3.529 ⁇ or less, more preferably 3.522 ⁇ or more and 3.526 ⁇ or less, even more preferably 3.523 ⁇ or more and 3.526 ⁇ or less, and even more preferably 3.524 ⁇ or more and 3.526 ⁇ or less.
  • the a-axis length of the crystal lattice in the crystal structure of nickel particles can be measured by an X-ray diffraction device using CuK ⁇ 1 radiation, as described in the Examples below.
  • the length is determined by the WPPF method, as described in the Examples below.
  • the crystallite size and a-axis length of the crystal lattice in the nickel crystal structure of the present invention can be achieved, for example, by adjusting the proportion of metal element M contained in the surface region of the nickel particles, or by reducing the thickness of the surface region of the nickel particles that contains the nickel-metal M alloy. In addition, or instead, they can also be achieved by appropriately adjusting the conditions in the manufacturing method of nickel particles described below.
  • the degree of sintering resistance of the nickel particles of the present invention can be evaluated by subjecting the nickel particles to thermomechanical analysis (TMA).
  • TMA thermomechanical analysis
  • the temperature at which the TMA shrinkage rate (%) based on room temperature (25°C) is 5% is defined as the shrinkage start temperature.
  • the temperature it is preferable for the temperature to be 400°C or higher. From the viewpoint of making this advantage more prominent, it is more preferable for the temperature to be 450°C or higher, even more preferable for the temperature to be 500°C or higher, even more preferable for the temperature to be 550°C or higher, and even more preferable for the temperature to be 570°C or higher.
  • nickel particles are produced by the so-called polyol method.
  • the polyol method is a method in which a polyol is used as a solvent that also serves as a reducing agent.
  • nickel chemical species are present in a polyol and heating is performed to cause a reduction reaction to the nickel base particles, and before the reduction reaction is completed, a compound of metal element M is mixed and further heating is performed to cause a reduction reaction to metal M, forming a surface region containing a nickel-metal M alloy on the nickel base particles.
  • nickel hydroxide As the nickel species for producing nickel particles, from the viewpoint of successfully obtaining the desired nickel particles.
  • Nickel hydroxide is added to a mixture containing polyol, polyvinylpyrrolidone (hereinafter also referred to as "PVP"), and polyethyleneimine (hereinafter also referred to as "PEI"). From the viewpoint of ease of handling, it is preferable to use nickel hydroxide in a particulate form.
  • the polyol contained in the mixed liquid is used as a solvent and also as a reducing agent for nickel hydroxide.
  • the polyol that can be used include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, and polyethylene glycol.
  • These polyols can be used alone or in combination of two or more.
  • ethylene glycol is preferred because it has a high reducing performance due to a large proportion of hydroxyl groups relative to the molecular weight, and is liquid at room temperature and therefore easy to handle.
  • the concentration of polyol in the mixed solution in the range of 50% by mass or more and 99.8% by mass or less.
  • PVP is used as a dispersant for nickel hydroxide.
  • PVP is preferable because it has a significant effect as a dispersant and can sharpen the particle size distribution of nickel particles generated by reduction.
  • the molecular weight of these PVPs can be appropriately adjusted depending on the degree of water solubility and dispersing ability.
  • the amount of PVP in the mixed solution is preferably 0.01 to 30 parts by mass per 100 parts by mass of nickel hydroxide converted into nickel. By setting it in this range, the dispersing effect can be fully expressed without excessively increasing the viscosity of the mixed solution.
  • PEI acts to reduce the number of nickel ions in the mixed solution while nickel nuclei are being generated in the mixed solution, preventing nucleation and nucleus growth from proceeding simultaneously. This is because (a) PEI has unshared electron pairs that interact with nickel ions and can form coordinate bonds with nickel ions, (b) PEI has a large amount of the unshared electron pairs, and (c) PEI has hydrogen bonding sites that can interact with the surface of nickel hydroxide that is present in an undissolved state in the mixed solution.
  • PEI polystyrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-sulftyrene, polystyrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-s
  • this manufacturing method by setting the ratio of PVP and PEI contained in the mixed solution within a specific range, it is possible to ensure that nickel nucleation and nucleus growth occur sequentially.
  • the amount of PEI in the mixture is set appropriately according to the amount of PVP, provided that the ratio of PVP to PEI satisfies the above-mentioned range.
  • the mixture can also contain a precious metal catalyst.
  • a precious metal catalyst for example, a precious metal compound such as a water-soluble salt of the precious metal can be used.
  • water-soluble salts of precious metals include water-soluble salts of palladium, silver, platinum, gold, etc.
  • palladium for example, palladium chloride, palladium nitrate, palladium acetate, ammonium palladium chloride, etc. can be used.
  • the precious metal catalyst can be added in the form of the above-mentioned compound or in the form of an aqueous solution in which the compound is dissolved in water.
  • the amount of precious metal catalyst contained in the mixed solution is preferably 0.01 to 5 parts by mass, particularly 0.01 to 1 part by mass, per 100 parts by mass of nickel hydroxide converted to nickel.
  • the mixture containing the above components is heated with stirring to reduce the nickel hydroxide.
  • the heating temperature depends on the type of polyol used, but by heating at atmospheric pressure at a temperature preferably between 150°C and 200°C, more preferably between 170°C and 200°C, and even more preferably between 190°C and 200°C, the nickel hydroxide can be successfully reduced to nickel mother particles.
  • a compound of metal element M is mixed into the mixed solution.
  • the compound of metal element M is mixed into the mixed solution while some nickel hydroxide remains.
  • "before the reduction reaction of nickel hydroxide is completed" refers to before 80 mol % or more of the charged amount of nickel hydroxide is reduced.
  • the metal element M is bismuth
  • the metal element M is bismuth
  • the metal element M is copper, from the same viewpoint as above, it is preferable to use, as the compound, at least one selected from the group consisting of copper nitrate trihydrate, copper sulfate pentahydrate, copper acetate monohydrate, copper hydroxide, cuprous oxide, and copper oxide, and it is particularly preferable to use copper sulfate pentahydrate.
  • the metal element M is iron, from the same viewpoint as above, it is preferable to use as the compound at least one selected from the group consisting of iron nitrate nonahydrate, iron chloride hexahydrate, iron sulfate heptahydrate, iron hydroxide, and iron oxide, and it is particularly preferable to use iron sulfate heptahydrate.
  • the metal element M is molybdenum
  • the amount of the bismuth compound in the mixed solution, converted into bismuth is preferably 0.003 parts by mass or more per part by mass of nickel in the feed, more preferably 0.004 parts by mass or more, even more preferably 0.01 parts by mass or more, and even more preferably 0.02 parts by mass or more, per part by mass of nickel in the feed.
  • the amount of the bismuth compound in the mixed solution, converted into bismuth is preferably 0.20 parts by mass or less per part by mass of nickel in the feed, more preferably 0.16 parts by mass or less, even more preferably 0.13 parts by mass or less, and even more preferably 0.12 parts by mass or less, per part by mass of nickel in the feed.
  • the amount of the copper compound in the mixed solution, converted into copper is preferably 0.004 parts by mass or more per part by mass of nickel in the feed, more preferably 0.01 parts by mass or more, even more preferably 0.022 parts by mass or more, and even more preferably 0.045 parts by mass or more, per part by mass of nickel in the feed.
  • the amount of the copper compound in the mixed solution, converted into copper is preferably 0.12 parts by mass or less per part by mass of nickel in the feed, more preferably 0.082 parts by mass or less, even more preferably 0.07 parts by mass or less, and even more preferably 0.06 parts by mass or less, per part by mass of nickel in the feed.
  • the amount of iron compounds in the mixed solution, converted into iron is preferably 0.0009 parts by mass or more per part by mass of nickel in the feed, more preferably 0.0028 parts by mass or more, even more preferably 0.004 parts by mass or more, and even more preferably 0.0047 parts by mass or more, per part by mass of nickel in the feed.
  • the amount of iron compounds in the mixed solution, converted into iron is preferably 0.12 parts by mass or less per part by mass of nickel in the feed, more preferably 0.08 parts by mass or less, even more preferably 0.06 parts by mass or less, even more preferably 0.030 parts by mass or less, and even more preferably 0.020 parts by mass or less, per part by mass of nickel in the feed.
  • the amount of the molybdenum compound in the mixed solution, converted into molybdenum is preferably 0.004 parts by mass or more per part by mass of nickel charged, more preferably 0.01 parts by mass or more, even more preferably 0.013 parts by mass or more, and even more preferably 0.016 parts by mass or more, per part by mass of nickel charged.
  • the amount of the molybdenum compound in the mixed solution, converted into molybdenum is preferably 0.12 parts by mass or less per part by mass of nickel charged, more preferably 0.07 parts by mass or less, even more preferably 0.06 parts by mass or less, even more preferably 0.051 parts by mass or less, and even more preferably 0.034 parts by mass or less, per part by mass of nickel charged.
  • the mixed solution containing the compound of the metal element M is heated while being stirred to reduce the nickel hydroxide and the compound in the mixed solution.
  • This reduction reaction reduces the nickel hydroxide remaining in the mixed solution to nickel, and if the metal element M is bismuth, the compound of the metal element M is reduced to bismuth.
  • the metal element M is copper, the compound of the metal element M is reduced to copper.
  • the metal element M is iron, the compound of the metal element M is reduced to iron.
  • the metal element M is molybdenum, the compound of the metal element M is reduced to molybdenum.
  • the nickel hydroxide and the compound of the metal element M are simultaneously reduced, and a surface region containing a nickel-metal M alloy in which the nickel element and the metal M are homogeneously dissolved in solid solution is formed on the surface of the nickel mother particle.
  • a part of the metal element M exists in the state of the simple substance of the metal element M, in the state of a compound of the metal element M, or in a state in which two or more of these are combined.
  • the heating temperature of the mixture depends on the type of polyol and metal element M compound used, but is preferably 150°C to 200°C under atmospheric pressure, more preferably 170°C to 200°C, and even more preferably 190°C to 200°C. By keeping the heating temperature within this range, nickel hydroxide and the metal element M compound can be reduced simultaneously, and a surface region containing nickel-metal M alloy can be successfully formed on the surface of the nickel mother particles.
  • the polyol in the resulting dispersion of nickel particles is replaced with water, and then the replaced water is replaced again with methanol to wash the nickel particles, followed by vacuum drying. In this manner, the nickel particles of the present invention can be produced.
  • a PVD method or CVD method can be performed by adding a raw material of metal element M to a nickel raw material.
  • a nickel-metal M alloy is formed throughout the nickel particles.
  • the content of metal element M, bismuth, copper, iron and/or molybdenum, in the entire nickel particle becomes excessively high, resulting in a problem of high electrical resistance.
  • the particle size of the nickel particles becomes uneven, and when a conductive film is formed using the nickel particles, the surface of the conductive film becomes rough, which is one of the causes of short circuits between the internal electrodes of the MLCC.
  • the metal element M when iron and/or molybdenum are used as the metal element M, a layer containing iron oxide and/or molybdenum oxide is formed on the surface of the nickel particles due to the fact that simple iron and molybdenum are easily oxidized.
  • nickel particles with such a layer are sintered during the manufacture of MLCC, the oxide contained in the layer is absorbed into the dielectric layer, and the sintering resistance of the nickel particles is not high.
  • the nickel particles of the present invention which are made of nickel mother particles and a nickel-metal M alloy arranged on the surface thereof, can increase the sintering resistance without excessively increasing the electrical resistance.
  • the surface of the conductive film can be made smooth. For these reasons, as described above, it is preferable to produce nickel particles by simultaneously reducing the nickel hydroxide and the compound of the metal element M while some of the nickel hydroxide remains.
  • the nickel particles produced by the above method are used in a variety of fields, taking advantage of the fact that they have a fine, uniform particle size and a surface region containing nickel-metal M alloy on the surface of the nickel particles. They are particularly suitable for use in forming the internal electrodes of MLCCs.
  • the metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
  • the content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
  • the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at%)
  • Coefficient of variation (%) ( ⁇ /D 50 ) ⁇ 100
  • the value of Cs/ D50 is 0.3 or more and 0.6 or less.
  • Nickel particles according to any one of [1] to [3].
  • a method for producing nickel particles comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles, The method for producing nickel particles, wherein the metal element M is at least one selected from bismuth, copper, iron and molybdenum.
  • Example 1 A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 12 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker.
  • the polyethyleneimine was branched and had a number average molecular weight of 1800.
  • the mixture was heated while stirring, and a reduction reaction was carried out at 198 ° C. under atmospheric pressure for 5 hours. At this point, the reduction of nickel hydroxide had progressed to 80 mol % with respect to the amount of nickel hydroxide charged.
  • the supernatant of the dispersion was removed.
  • the series of operations was repeated five times.
  • 50 g of methanol was added and the dispersion was stirred for 10 minutes.
  • the supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. After that, the dispersion was vacuum dried at 80° C. to obtain nickel particles.
  • Example 2 The amount of the aqueous palladium nitrate solution and the amount of bismuth chloride added, as well as the time from the start of heating the mixed solution to the addition of bismuth chloride to the mixed solution, were as shown in Table 1. Other than these, nickel particles were obtained in the same manner as in Example 1.
  • Example 7 Copper sulfate pentahydrate was added in place of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the copper sulfate pentahydrate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
  • Example 8 Iron sulfate heptahydrate was added in place of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the iron sulfate heptahydrate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
  • Example 9 Sodium molybdate was added instead of bismuth chloride.
  • the amounts of the aqueous palladium nitrate solution and the sodium molybdate added were as shown in Table 1.
  • Nickel particles were obtained in the same manner as in Example 1 except for the above.
  • Comparative Example 1 A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 8 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker.
  • the polyethyleneimine was branched and had a number average molecular weight of 1800.
  • the mixture was heated with stirring and reduced at 198°C for 6.5 hours. The reduction was terminated by stopping the heating, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
  • a magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition.
  • 50 g of pure water was added and the dispersion was stirred for 10 minutes.
  • the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed.
  • the series of operations was repeated five times.
  • 50 g of methanol was added and the dispersion was stirred for 10 minutes.
  • the supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. After that, the dispersion was vacuum dried at 80° C. to obtain a powder of nickel particles.
  • Comparative Example 3 A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 8 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker.
  • the polyethyleneimine was branched and had a number average molecular weight of 1800.
  • the mixture was heated with stirring and reduced at 198°C for 6.5 hours. The reduction was terminated by stopping the heating, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
  • a magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition. After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
  • X-ray photoelectron spectroscopy (XPS) measurement The sample to be measured for XPS was made by molding nickel particles into pellets using a press. In detail, about 10 mg of the particle sample was placed in an aluminum container having dimensions of ⁇ 5.2 mm and height 2.5 mm. Then, using a press (manufactured by AS ONE, product number: 1-312-01) and an adapter (product number: 1-312-03), pressure was applied together with the aluminum container at a predetermined stroke (25 mm). The nickel particle pellets supported by the aluminum container were then removed. The obtained pellet molded product was subjected to surface measurement and depth measurement from the sample surface to the inside by sputtering with Ar monomer ions. The measurement conditions were as follows.
  • Measurement device VersaProbeIII manufactured by ULVAC-PHI, Inc.
  • Excitation X-ray Monochromatic Al-K ⁇ ray (1486.7 eV)
  • Output 50W
  • Acceleration voltage 15 kV ⁇ X-ray irradiation diameter: 200 ⁇ m ⁇ ⁇ X-ray scanning area: 1000 ⁇ m ⁇ 300 ⁇ m
  • Detection angle 45°
  • Pass energy 26.0 eV
  • Energy step 0.1 eV/step
  • Sputter ion species Ar monomer ions
  • Sputter rate 3.3 nm/min ( SiO2 equivalent)
  • Sputtering interval 20 s
  • Measurement elements C 1s , Ni 2p3 , Sn 3d5 , Bi 4f , Cu 2p , Fe 3p , Mo 3d Energy correction value: C—C bond and C—H bond in C 1s (284.8 eV)
  • a-axis length and crystallite size Cs The a-axis length and crystallite size Cs of the nickel particles obtained in the examples and comparative examples were calculated using the WPPF method from the diffraction peaks derived from nickel obtained by X-ray diffraction measurement.
  • the X-ray diffraction pattern obtained under the above measurement conditions was analyzed using analysis software under the following conditions.
  • the analysis was corrected using data obtained from lanthanum hexaboride powder (SRM660 series), a standard material provided by the National Institute of Standards and Technology (NIST).
  • SRM660 series lanthanum hexaboride powder
  • NIST National Institute of Standards and Technology
  • the a-axis length and crystallite size Cs were calculated using the WPPF method.
  • TMA/SS6000 manufactured by Seiko Instruments Inc. was used as the TMA measuring device. 0.2-0.3 g of nickel particles were placed in a stainless steel mold container with a diameter of 5.0 mm, and a pressure of 92 MPa was applied to the nickel particles to produce a pellet. The pellet length of the obtained pellet was measured and used as the measurement target sample. This was set in the measuring device, and the sample was heated at 5°C/min under a load of 49 mN and an atmosphere of 1% by volume hydrogen/99% by volume nitrogen. Measurement was started from room temperature (25°C), and a graph showing the relationship between temperature and shrinkage rate (%) was obtained. The shrinkage start temperature was determined from the obtained graph.
  • the surface roughness Rz of the sintered film was measured using a SURFCOM 130A.
  • the measurement conditions were an evaluation length of 6.0 mm and a measurement speed of 0.6 mm/s.
  • the nickel particles obtained in Examples 1 to 9 contain metallic bismuth, copper, iron, or molybdenum elements in their surface regions. Furthermore, the a-axis length of the nickel particles obtained in the examples was longer than the a-axis length of the nickel particles obtained in Comparative Example 1, which did not use compounds of bismuth, copper, iron, and molybdenum. From these results, it is understood that the nickel particles obtained in Examples 1 to 6 contain an alloy of nickel and bismuth in their surface regions. It is also understood that the nickel particles obtained in Example 7 contain an alloy of nickel and copper in their surface regions. It is also understood that the nickel particles obtained in Example 8 contain an alloy of nickel and iron in their surface regions.
  • the nickel particles obtained in Example 9 contain an alloy of nickel and molybdenum in their surface regions. Furthermore, as is clear from the results shown in Table 1, the nickel particles obtained in Examples 1 to 9 exhibited a higher shrinkage initiation temperature than the nickel particles obtained in Comparative Examples 1 to 3. This shows that the nickel particles obtained in Examples 1 to 9 exhibit high sintering resistance. In particular, as is clear from the comparison between Examples 1 to 5 and Example 6, it is found that the resistivity of the sintered film obtained from the nickel particles can be controlled by controlling the amount of bismuth contained in the nickel particles.
  • Example 1 to 6 in which nickel particles having a surface region in which an alloy of nickel and bismuth was formed were produced, the surface of the sintered film was smoother than in Comparative Example 2 in which an alloy of nickel and bismuth was formed over the entire nickel particle. This shows that the surface roughness of the sintered film is reduced by using nickel particles having a surface region containing an alloy of nickel and bismuth.
  • the present invention provides nickel particles that are highly sinter-resistant without excessively increasing electrical resistance.

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Abstract

Selon la présente invention, des particules de nickel comprennent une région de surface comprenant un alliage d'un élément métallique M et de nickel. L'élément métallique M est au moins un type d'élément choisi parmi le bismuth, le cuivre, le fer et le molybdène. La teneur de l'élément métallique M par rapport aux particules de nickel dans son ensemble est de 0,09 % en masse à 15,8 % en masse. Lorsqu'une région allant d'une surface supérieure à une profondeur de pulvérisation cathodique de 5 nm par conversion de SiO2 est mesurée dans la direction de la profondeur des particules de nickel par analyse par spectroscopie photoélectronique à rayons X, la valeur de X/Y est de 0,5 à 35, X (% atomiques) étant la valeur maximale du rapport du nombre d'atomes de l'élément métallique M au nombre total d'atomes de l'élément nickel et de l'élément métallique M dans ladite région, et Y (% atomiques) étant le rapport du nombre d'atomes de l'élément métallique M au nombre total d'atomes de l'élément nickel et de l'élément métallique M dans ladite région lorsque les particules de nickel sont mesurées par spectrométrie d'émission à plasma à couplage inductif (ICP).
PCT/JP2023/023990 2022-09-30 2023-06-28 Particules de nickel et procédé de fabrication de particules de nickel WO2024070098A1 (fr)

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JP2007254781A (ja) * 2006-03-21 2007-10-04 Toyota Central Res & Dev Lab Inc 金属粒子及びその製造方法
JP2008050691A (ja) * 2006-07-28 2008-03-06 Furukawa Electric Co Ltd:The 微粒子の製造方法及び該製造方法により得られる微粒子、微粒子分散液の製造方法及び該製造方法により得られる微粒子分散液、並びに導電部材
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