WO2023214558A1 - Method for producing fine particles, and colloidal solution - Google Patents

Method for producing fine particles, and colloidal solution Download PDF

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Publication number
WO2023214558A1
WO2023214558A1 PCT/JP2023/017011 JP2023017011W WO2023214558A1 WO 2023214558 A1 WO2023214558 A1 WO 2023214558A1 JP 2023017011 W JP2023017011 W JP 2023017011W WO 2023214558 A1 WO2023214558 A1 WO 2023214558A1
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fine particles
oxidation
solution
producing fine
container
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PCT/JP2023/017011
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French (fr)
Japanese (ja)
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博史 後藤
貴宏 中村
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株式会社illuminus
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
    • 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
    • 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

Definitions

  • the present invention relates to a method for producing fine particles and a colloidal solution.
  • Patent Document 1 Conventionally, as a method for producing fine particles such as fine particles using a laser, a method for producing fine particles such as that disclosed in Patent Document 1 has been proposed, for example.
  • Patent Document 1 discloses a method of generating metal fine particles by irradiating a basic solvent in which one or more metal ions are dissolved with a femtosecond pulse laser.
  • Patent Document 1 assumes that water is used as the basic solvent. Therefore, when a solvent in which metal ions are dissolved is irradiated with a laser, the generated fine particles may be oxidized. As a result, there is a concern that, for example, surface treatment for imparting functionality to the fine particles is restricted, and the uses of the fine particles are restricted.
  • the present invention was devised in view of the above-mentioned problems, and its purpose is to provide a method for producing fine particles and a colloidal solution that can expand the uses of fine particles. be.
  • the method uses a femtosecond pulse laser to produce fine particles, and the method includes:
  • the method is characterized by comprising a step of forming a solution in a container, and an irradiation step of condensing the femtosecond pulse laser and irradiating the solution.
  • the precursor contains a metal salt, and the oxidation-inhibiting solvent contains alcohol.
  • the redox potential of the metal ion contained in the metal salt is negative.
  • the metal salt includes two or more types of materials exhibiting a negative redox potential.
  • the oxidation-inhibiting solvent contains only the alcohol.
  • the precursor in the first invention, includes solid particles having a larger median diameter than the median diameter of the fine particles.
  • the precursor contains an organometallic complex
  • the oxidation-inhibiting solvent contains a material having a phenyl group
  • the irradiation step includes irradiating the solution with the femtosecond pulse laser through the container.
  • the container in any one of the first to seventh inventions, includes a lid that covers the opening of the container.
  • the colloidal solution in the tenth invention comprises the fine particles produced by the method for producing fine particles according to any one of the first to fourth inventions, and a solvent in which the fine particles are dispersed.
  • the solvent contains a compound having an aldehyde group.
  • a solution containing a mixture of a precursor and an oxidation-inhibiting solvent is irradiated with a focused femtosecond pulse laser. Therefore, by using the oxidation-inhibiting solvent, it is possible to suppress the oxidation of the fine particles generated due to laser irradiation, and, for example, it is possible to perform arbitrary surface treatment on the surfaces of the fine particles. This makes it possible to expand the uses of the fine particles.
  • the precursor contains a metal salt
  • the oxidation-inhibiting solvent contains alcohol. Therefore, by utilizing the oxidation reaction of alcohol, it is possible to easily maintain the suppression of oxidation of the fine particles generated based on the metal salt. This makes it possible to suppress deterioration in quality of the fine particles over time.
  • the redox potential of the metal ions contained in the metal salt is negative. Therefore, even when fine particles with characteristics that are easily oxidized are generated by the irradiation process, the oxidation reaction of alcohol can be used to suppress the oxidation of the fine particles, which was previously considered difficult to generate. can be generated. This makes it possible to further expand the uses of the fine particles.
  • the metal salt includes two or more types of materials whose redox potential is negative. Therefore, even when fine particles of alloys with characteristics that are easily oxidized are generated, the oxidation of the fine particles can be suppressed by using the oxidation reaction of alcohol. Fine particles can be generated. This makes it possible to further expand the uses of the fine particles.
  • the oxidation-inhibiting solvent contains only alcohol. Therefore, factors that promote oxidation of fine particles in the solution can be reduced. This makes it possible to suppress deterioration in the quality of the fine particles.
  • the precursor includes solid particles having a larger median diameter than the median diameter of the fine particles. Therefore, when generating fine particles with laser irradiation, unnecessary residues etc. generated from the precursor can be suppressed. This makes it possible to form fine particles with high purity.
  • the precursor includes an organometallic complex
  • the oxidation-inhibiting solvent includes a material having a phenyl group. Therefore, the fine particles generated by laser irradiation can contain carbon based on phenyl groups. As a result, oxidation of the fine particles can be suppressed without maintaining the dispersed state in alcohol or the like. This makes it possible to easily store fine particles with oxidation suppressed.
  • the solution in the irradiation step, is irradiated with a femtosecond pulse laser through the container. Therefore, the possibility of ignition caused by alcohol or the like can be suppressed compared to the case where femtosecond pulse laser is irradiated from the interface between the solution and the atmosphere. This makes it possible to improve safety when producing fine particles.
  • the container includes a lid that covers the opening of the container. Therefore, volatilization of the solution can be suppressed. This makes it possible to suppress changes over time during the production of fine particles.
  • the colloidal solution includes a solvent in which fine particles are dispersed. This makes it possible to provide a colloidal solution that maintains a state in which oxidation of fine particles is suppressed.
  • the solvent contains a compound having an aldehyde group. Therefore, by utilizing the reducing property of the aldehyde group, it is possible to maintain a state in which oxidation of the fine particles is suppressed. This makes it possible to maintain the quality of the fine particles.
  • FIG. 1 is a schematic perspective view showing an example of a manufacturing apparatus used in the method for manufacturing fine particles in this embodiment.
  • FIG. 2 is a flowchart illustrating an example of the method for producing fine particles in this embodiment.
  • the fine particles in this embodiment are used not only in electronic devices such as power generation elements, but also in fields such as medicine and food.
  • the fine particles include not only metal fine particles but also non-metal fine particles.
  • Fine particles can be used, for example, in the energy field, such as power generation elements, and in the electronic device field, such as conductive parts.
  • fine particles can be used, for example, in the medical field as pharmaceuticals or cosmetics, the material field as part of composite materials, and the food field.
  • fine particles having additional functions can be produced, which is expected to be used in a variety of applications.
  • the fine particles include a plurality of particles having a particle diameter of, for example, 1 nm or more and 100 nm or less.
  • the fine particles may include, for example, particles having a median diameter (median diameter: D50) of 1 nm or more and 10 nm or less, and may also include, for example, particles having an average particle diameter of 1 nm or more and 10 nm or less.
  • the median diameter or average particle diameter can be measured, for example, using a particle size distribution meter.
  • a particle size distribution measuring device using a dynamic light scattering method for example, Zetasizer Ultra manufactured by Malvern Panalytical, etc.
  • fine particles may also refer to a particle group including two or more types of particles, each of which is generated by a different type of atom, for example.
  • the fine particles may represent, for example, a group of particles of a compound (for example, an alloy) containing two or more types of atoms.
  • the colloidal solution in this embodiment is used in the same field as fine particles.
  • a colloidal solution refers to a state in which two or more types of substances including, for example, fine particles are mixed.
  • a colloidal solution includes, for example, a solvent in which fine particles are dispersed.
  • a colloidal solution includes, for example, a solvent containing alcohol and fine particles dispersed in the solvent, and the surfaces of the fine particles are in contact with the solvent. That is, no oxide film is formed on the surface of the fine particles, and the metal surface is in direct contact with the solvent. Therefore, the oxidation reaction of alcohol can be used to suppress the oxidation of the fine particles, and, for example, the fine particles can be subjected to arbitrary surface treatment. This makes it possible to expand the uses of the fine particles.
  • the colloidal solution may be stored, for example, in any container, such as a container filled with nitrogen, a reduced pressure environment, etc., where oxygen interference is suppressed. In this case, oxidation of the fine particles over time can be easily suppressed. This makes it possible to easily maintain the quality of the fine particles.
  • the solvent includes, for example, a monovalent alcohol such as ethanol, methanol, 1-propanol, and the like.
  • a monovalent alcohol such as ethanol, methanol, 1-propanol, and the like.
  • the solvent may contain at least one of acetaldehyde produced by oxidation of ethanol and acetic acid produced by oxidation of acetaldehyde.
  • the solvent may include, for example, the same material as the oxidation-inhibiting solvent described below.
  • the solvent may contain a compound having an aldehyde group.
  • the solvent may contain a compound having an aldehyde group.
  • the fine particles contain one or more base metal materials.
  • the colloidal solution fine particles having characteristics that are easily oxidized can be kept in contact with the solvent, and oxidation of the fine particles can be suppressed. This makes it possible to suppress deterioration in the quality of the fine particles.
  • fine particles contain two or more types of materials that exhibit the same crystal structure.
  • the crystal structure of the entire fine particles of the alloy tends to be the same, it is possible to stabilize the fine particles. This makes it possible to suppress deterioration in the quality of the fine particles and improve the stability of the fine particles.
  • FIG. 1 is a schematic perspective view showing an example of a manufacturing apparatus 100 in this embodiment.
  • the manufacturing apparatus 100 includes, for example, a laser device 1, a lens 2, a container 3, and a solution 4, as shown in FIG.
  • the manufacturing apparatus 100 may include a plurality of containers 3 and solutions 4 for one laser device 1, for example.
  • the laser device 1 emits a pulsed laser having a time width of, for example, about 10 ⁇ 15 seconds.
  • a femtosecond pulse laser such as Astrella manufactured by COHERENT, which exhibits the following characteristics, can be used.
  • Laser wavelength 800nm ⁇ 20nm
  • Pulse width 100fs Energy: 5-9mJ
  • Repetition frequency 100Hz (output 0.5-0.9W)
  • the laser device 1 may be, for example, Spitfire Pro manufactured by Spectra Physics, and can be arbitrarily selected depending on the application. Note that the laser emitted from the laser device 1 has an energy of about several mJ, and it is difficult to efficiently generate fine particles with energy of about several ⁇ J, which is used for example in laser processing.
  • the lens 2 condenses the laser emitted from the laser device 1.
  • the light intensity can be increased in a specific area.
  • the laser can be focused inside the solution 4 rather than at the interface of the solution 4.
  • a known lens such as a condenser lens is used.
  • Container 3 contains solution 4.
  • a transparent material is used as the container 3, for example a fused silica cuvette.
  • a material having a lower absorption rate at a wavelength around 800 nm than around 400 nm is used as the container 3. In this case, when irradiating the laser through the container 3, it is possible to suppress a decrease in the production efficiency of fine particles.
  • the container 3 may include, for example, a lid 31 that covers the opening 3a. In this case, volatilization of alcohol can be suppressed. This makes it possible to suppress changes over time during the production of fine particles.
  • the same material as the container 3 may be used, or a material that is resistant to alcohol may be used.
  • the shape of the lid 31 may be in addition to a plate shape, for example, a shape having an edge for fitting into the opening 3a.
  • Solution 4 is a liquid mixture of a fine particle precursor and an oxidation-inhibiting solvent.
  • the oxidation-inhibiting solvent inhibits oxidation of the fine particles. Fine particles are generated by irradiating the solution 4 with a laser.
  • Precursors include, for example, metal salts.
  • the oxidation-inhibiting solvent includes, for example, alcohol.
  • the concentration of the metal salt in the solution 4 is, for example, about 1.0 ⁇ 10 ⁇ 5 mol ⁇ dm ⁇ 3 or more and 1.0 ⁇ 10 ⁇ 1 mol ⁇ dm ⁇ 3 or less, and can be set arbitrarily depending on the purpose of the generated fine particles. Can be set to
  • the metal salt contains a known compound containing a metal ion, and can contain any material depending on the purpose.
  • Metal salts contain one or more materials. For example, when the metal salt contains two or more types of materials, fine particles of an alloy containing each material can be produced.
  • known metal salts such as HAuCl 4.3H 2 O and H 2 PtCl 6.6H 2 O are used.
  • the redox potential of the metal ion contained in the metal salt may be negative.
  • a material containing a base metal such as FeCl 3 .6H 2 O or NiCl 2 .6H 2 O is used as the metal salt.
  • the oxidation reaction of the fine particles can be suppressed by utilizing the oxidation reaction of the alcohol contained in the oxidation-inhibiting solvent. As a result, it is possible to generate fine particles that have been difficult to generate in the past. Therefore, it becomes possible to further expand the uses of the fine particles.
  • the metal salt includes, for example, two or more types of materials.
  • the metal salt may include at least one material having a negative redox potential.
  • the oxidation reaction of the alcohol contained in the oxidation-inhibiting solvent can be used to suppress the oxidation reaction of the fine particles containing two or more types of materials. As a result, it is possible to generate fine particles that have been difficult to generate in the past. Therefore, it becomes possible to further expand the uses of the fine particles.
  • the metal salt may include two or more types of materials that exhibit negative redox potential.
  • two types of materials are used as metal salts, such as FeCl 3 .6H 2 O and NiCl 2 .6H 2 O.
  • oxidation of the fine particles can be suppressed by utilizing the oxidation reaction of alcohol contained in the oxidation-inhibiting solvent.
  • oxidation-reduction potential indicates a known value described in, for example, the Analytical Chemistry Data Book (Maruzen Publishing).
  • base metal refers to metals whose metal ions are classified as having a negative redox potential, such as lithium, potassium, calcium, sodium, magnesium, aluminum, zinc, iron, nickel, tin, and lead.
  • the metal salt may contain two or more types of materials exhibiting the same crystal structure.
  • the crystal structure of the entire fine particles of the produced alloy tends to be the same, so that the fine particles can be stabilized. This makes it possible to improve the stability of the fine particles.
  • the crystal structures of iron, sodium, and potassium exhibit a body-centered cubic lattice. Therefore, by containing a material containing at least two of iron, sodium, and potassium as a metal salt, the entire fine particles of the produced alloy tend to have the same crystal structure.
  • the crystal structures of nickel, aluminum, and calcium exhibit face-centered cubic lattices. Therefore, by containing a material containing at least two of nickel, aluminum, and calcium as a metal salt, the crystal structure of the entire fine particles of the produced alloy tends to be the same.
  • the oxidation-inhibiting solvent includes a known alcohol having a hydroxy group.
  • the oxidation-inhibiting solvent may include a monohydric alcohol, such as ethanol, methanol, 1-propanol, and the like.
  • the oxidation-inhibiting solvent may include, for example, a compound having at least one of an aldehyde group and a carboxyl group.
  • the oxidation-inhibiting solvent may contain only alcohol. In this case, factors that promote oxidation of the generated fine particles in the solution 4 can be reduced. This makes it possible to suppress deterioration in the quality of the fine particles.
  • FIG. 2 is a flowchart illustrating an example of the method for producing fine particles in this embodiment.
  • the method for producing fine particles includes a solution forming step S110 and an irradiation step S120.
  • a solution 4 in which a precursor and an oxidation-inhibiting solvent are mixed is formed in the container 3.
  • the precursor contains a metal salt
  • the oxidation-inhibiting solvent contains alcohol.
  • the above-mentioned materials are used as the metal salt and alcohol.
  • the solution 4 can be formed by, for example, placing the precursor and the oxidation-inhibiting solvent in the container 3 and then stirring them using a stirrer.
  • the oxidation-inhibiting solvent may be added in stages. In this case, the concentration of the precursor can be easily adjusted.
  • the precursor and the oxidation-inhibiting solvent may be put into a preparation container to form the solution 4, and the solution 4 may be transferred into the container 3.
  • ⁇ Irradiation step S120 In the irradiation step S120, a femtosecond pulse laser is focused and the solution 4 is irradiated.
  • the solvent molecules for example, ethanol molecules when the oxidation-inhibiting solvent is ethanol
  • the solvent molecules for example, ethanol molecules when the oxidation-inhibiting solvent is ethanol
  • the metal ions contained in the precursor are reduced by free electrons among the generated radicals, and fine particles are generated. In this way, by irradiating the solution 4 with a laser, fine particles based on the precursor are generated.
  • a laser is irradiated onto the solution 4 that is a mixture of a precursor containing a metal salt and an oxidation-inhibiting solvent containing an alcohol.
  • a compound having an aldehyde group is produced by oxidation of the alcohol. That is, the oxidation reaction of the fine particles generated by the oxidation reaction of alcohol can be suppressed. Therefore, formation of an oxide film on the surface of the fine particles can be suppressed.
  • the solution 4 may be irradiated with a laser through the container 3, for example.
  • the possibility of ignition caused by alcohol or the like can be suppressed compared to the case where the laser is irradiated from the interface between the solution 4 and the atmosphere. This makes it possible to improve safety when producing fine particles.
  • the solution 4 may be irradiated with a laser, for example, with the lid 31 covering the opening 3a of the container 3 provided. In this case, volatilization of the solution 4 can be suppressed. This makes it possible to suppress changes over time during the production of fine particles.
  • a film forming step S130 may be performed.
  • a film containing an arbitrary material is formed on the surface of the fine particles using, for example, a known phase transfer method.
  • the solution 4 in which the precursor and the oxidation-inhibiting solvent are mixed is irradiated with a focused femtosecond pulse laser. Therefore, by using an oxidation-inhibiting solvent, it is possible to suppress the oxidation of fine particles generated due to laser irradiation, and, for example, it is possible to easily perform arbitrary surface treatment (for example, forming a film) on the surface of fine particles. . This makes it possible to expand the uses of the fine particles.
  • the precursor includes a metal salt
  • the oxidation-inhibiting solvent includes alcohol. Therefore, by utilizing the oxidation reaction of alcohol, it is possible to easily maintain the suppression of oxidation of the fine particles generated based on the metal salt. This makes it possible to suppress deterioration in quality of the fine particles over time.
  • the redox potential of the metal ions contained in the metal salt is negative. Therefore, even when fine particles with characteristics that are easily oxidized are generated in the irradiation step S120, the oxidation of the fine particles can be suppressed by using the oxidation reaction of alcohol, which was previously considered difficult to generate. Fine particles can be generated. This makes it possible to further expand the uses of the fine particles.
  • the metal salt includes two or more types of materials whose redox potential is negative. Therefore, even when fine particles of alloys with characteristics that are easily oxidized are generated, the oxidation of the fine particles can be suppressed by using the oxidation reaction of alcohol. Fine particles can be generated. This makes it possible to further expand the uses of the fine particles.
  • the oxidation-inhibiting solvent contains only alcohol. Therefore, in the solution 4, factors that promote oxidation of the fine particles can be reduced. This makes it possible to suppress deterioration in the quality of the fine particles.
  • the solution 4 is irradiated with a femtosecond pulse laser through the container 3. Therefore, the possibility of ignition caused by alcohol or the like can be suppressed compared to the case where femtosecond pulse laser is irradiated from the interface between the solution 4 and the atmosphere. This makes it possible to improve safety when producing fine particles.
  • the container 3 includes a lid 31 that covers the opening 3a of the container 3. Therefore, volatilization of the solution 4 can be suppressed. This makes it possible to suppress changes over time during the production of fine particles.
  • the colloidal solution includes a solvent in which fine particles are dispersed. This makes it possible to provide a colloidal solution that maintains a state in which oxidation of fine particles is suppressed.
  • the solvent includes a compound having an aldehyde group. Therefore, by utilizing the reducing property of the aldehyde group, it is possible to maintain a state in which oxidation of the fine particles is suppressed. This makes it possible to maintain the quality of the fine particles.
  • the precursor includes solid particles.
  • the solid particles include a plurality of particles having a finite particle diameter of, for example, 500 ⁇ m or less.
  • the solid particles have a median diameter that is larger than the median diameter of the fine particles produced.
  • the solid particles have a median diameter of, for example, 50 nm or more and about 100 ⁇ m.
  • the material of the solid particles is directly reflected in the material of the fine particles to be generated, so it can be arbitrarily set depending on the type of fine particles to be generated.
  • the fine particles produced contain gold.
  • the solid particles do not contain materials that are not contained in fine particles, such as chlorine. Therefore, generation of unnecessary material due to the generation of fine particles can be suppressed.
  • the oxidation-inhibiting solvent may include alcohol. In this case as well, as in the embodiment described above, oxidation of the generated fine particles can be suppressed.
  • the solution 4 may be stirred.
  • the solid particles can be maintained in a dispersed state in the solution 4, and it is possible to improve the production efficiency of fine particles.
  • the precursor includes solid particles having a median diameter larger than the median diameter of the microparticles. Therefore, when generating fine particles with laser irradiation, unnecessary residues etc. generated from the precursor can be suppressed. This makes it possible to form fine particles with high purity.
  • the precursor includes an organometallic complex.
  • the oxidation-inhibiting solvent includes a material having a phenyl group.
  • organometallic complexes examples include alkyl complexes such as CH 3 Li (methyl lithium) and CH 3 CH 2 MgBr (ethyl Grignard), aromatic complexes such as Fe (C 5 H 5 ) 2 (ferrocene), and Cu (C In addition to an acetylacetone complex such as 5 H 7 O 2 ) 2 (copper acetylacetonate), known materials can be used.
  • benzene, toluene, etc. are used as the material having a phenyl group.
  • the precursor includes an organometallic complex
  • the oxidation-inhibiting solvent includes a material having a phenyl group. Therefore, the fine particles generated by laser irradiation can contain carbon based on phenyl groups. As a result, oxidation of the fine particles can be suppressed without maintaining the dispersed state in alcohol or the like. This makes it possible to easily store fine particles with oxidation suppressed.
  • the fine particles and colloidal solution produced by the above-described fine particle manufacturing method can be expected to have the following uses, for example.
  • materials for the microparticles used including gold, platinum, and gold-silver alloys.
  • they can become a variable for optimizing the characteristics of artificial photosynthesis.
  • materials for fine particles currently being researched include nickel and barium/titanium oxide (BaTiO 3 ).
  • the fine particles produced by the above-described fine particle manufacturing method contain known metal atoms such as nickel, platinum, gold, titanium, and the like.
  • the fine particles may contain, for example, two or more types of arbitrary atoms.
  • the fine particles may exhibit, for example, a perovskite structure.
  • the fine particles include, for example, barium titanate (BaTiO 3 ), strontium titanate (SrTiO 3 ), calcium titanate (CaTiO 3 ), lead titanate (PbTiO 3 ), tin titanate (SnTiO 3 ), and cadmium titanate (CdTiO 3 ) . ), and strontium zirconate (SrZrO 3 ).
  • the fine particles may represent, for example, a solid solution in which two or more types of metal atoms are combined. In this case, compared to fine particles that do not exhibit a solid solution, local state changes and chemical changes in the fine particles are less likely to occur. This makes it possible to further improve the stability of the fine particles.
  • Examples of combinations of metal atoms contained in fine particles exhibiting a solid solution include a combination of nickel and platinum, a combination of nickel and ruthenium, a combination of nickel and rhodium, a combination of nickel and palladium, and a combination of nickel and iridium. Examples include combinations. Examples of the combination of metal atoms contained in the fine particles exhibiting a solid solution include a combination of metal atoms such that the enthalpy of mixing is 0 or less.
  • the fine particles may represent, for example, a eutectic in which two types of metal atoms are combined.
  • the stability of the fine particles can be improved compared to fine particles that do not exhibit a eutectic.

Abstract

[Problem] To provide: a method for producing fine particles with which it is possible to expand the uses of the fine particles; and a colloidal solution. [Solution] This method for producing fine particles, using a femtosecond pulse laser, is characterized by comprising: a solution forming step for forming, in a container, a solution obtained by mixing a precursor of fine particles and an oxidation-inhibiting solvent that suppresses oxidation of the fine particles; and a radiation step for concentrating the femtosecond pulse laser and irradiating the solution therewith. For example, the precursor includes a metal salt, and the oxidation-inhibiting solvent includes an alcohol. For example, the metal salt includes at least two materials, each having a negative redox potential.

Description

微粒子の製造方法、及びコロイド溶液Method for producing fine particles and colloidal solution
　この発明は、微粒子の製造方法、及びコロイド溶液に関する。 The present invention relates to a method for producing fine particles and a colloidal solution.
　従来、レーザーを用いて微粒子等の微粒子を生成する方法として、例えば特許文献１に開示されたような微粒子の製造方法が提案されている。 Conventionally, as a method for producing fine particles such as fine particles using a laser, a method for producing fine particles such as that disclosed in Patent Document 1 has been proposed, for example.
　特許文献１には、１種以上の金属イオンを溶解させた基本溶媒に、フェムト秒パルスレーザーを照射して金属微粒子を生成する方法が開示されている。 Patent Document 1 discloses a method of generating metal fine particles by irradiating a basic solvent in which one or more metal ions are dissolved with a femtosecond pulse laser.
特開２０２１－０１７６２２号公報JP2021-017622A
　ここで、特許文献１では、基本溶媒として水を用いることを前提としている。このため、金属イオンを溶解させた溶媒に対してレーザーを照射した際、生成された微粒子が酸化される恐れがある。これにより、例えば微粒子に機能性を持たせるための表面処理に制限が生じ、微粒子の用途が制限される懸念が挙げられる。 Here, Patent Document 1 assumes that water is used as the basic solvent. Therefore, when a solvent in which metal ions are dissolved is irradiated with a laser, the generated fine particles may be oxidized. As a result, there is a concern that, for example, surface treatment for imparting functionality to the fine particles is restricted, and the uses of the fine particles are restricted.
　そこで本発明は、上述した問題点に鑑みて案出されたものであり、その目的とするところは、微粒子の用途の拡大を図ることができる微粒子の製造方法、及びコロイド溶液を提供することにある。 The present invention was devised in view of the above-mentioned problems, and its purpose is to provide a method for producing fine particles and a colloidal solution that can expand the uses of fine particles. be.
　第１発明における微粒子の製造方法によれば、フェムト秒パルスレーザーを用いた微粒子の製造方法であって、微粒子の前駆体と、前記微粒子の酸化を抑制する酸化抑制溶媒とを混合した溶液を、容器内に形成する溶液形成工程と、前記フェムト秒パルスレーザーを集光し、前記溶液に対して照射する照射工程と、を備えることを特徴とする。 According to the method for producing fine particles in the first aspect of the invention, the method uses a femtosecond pulse laser to produce fine particles, and the method includes: The method is characterized by comprising a step of forming a solution in a container, and an irradiation step of condensing the femtosecond pulse laser and irradiating the solution.
　第２発明における微粒子の製造方法によれば、第１発明において、前記前駆体は、金属塩を含み、前記酸化抑制溶媒は、アルコールを含むことを特徴とする。 According to the method for producing fine particles in the second invention, in the first invention, the precursor contains a metal salt, and the oxidation-inhibiting solvent contains alcohol.
　第３発明における微粒子の製造方法によれば、第２発明において、前記金属塩に含まれる金属イオンの酸化還元電位は、負を示すことを特徴とする。 According to the method for producing fine particles in the third invention, in the second invention, the redox potential of the metal ion contained in the metal salt is negative.
　第４発明における微粒子の製造方法によれば、第２発明において、前記金属塩は、酸化還元電位が負を示す２種類以上の材料を含むことを特徴とする。 According to the method for producing fine particles in the fourth invention, in the second invention, the metal salt includes two or more types of materials exhibiting a negative redox potential.
　第５発明における微粒子の製造方法によれば、第２発明において、前記酸化抑制溶媒は、前記アルコールのみを含むことを特徴とする。 According to the method for producing fine particles in the fifth invention, in the second invention, the oxidation-inhibiting solvent contains only the alcohol.
　第６発明における微粒子の製造方法によれば、第１発明において、前記前駆体は、前記微粒子の中央径よりも大きい中央径を有する固体粒子を含むことを特徴とする。 According to the method for producing fine particles in the sixth invention, in the first invention, the precursor includes solid particles having a larger median diameter than the median diameter of the fine particles.
　第７発明における微粒子の製造方法によれば、第１発明において、前記前駆体は、有機金属錯体を含み、前記酸化抑制溶媒は、フェニル基を有する材料を含むことを特徴とする。 According to the method for producing fine particles in the seventh invention, in the first invention, the precursor contains an organometallic complex, and the oxidation-inhibiting solvent contains a material having a phenyl group.
　第８発明における微粒子の製造方法によれば、第１発明～第７発明の何れかにおいて、前記照射工程は、前記容器を介して、前記溶液に対して前記フェムト秒パルスレーザーを照射することを特徴とする。 According to the method for producing fine particles in the eighth invention, in any one of the first to seventh inventions, the irradiation step includes irradiating the solution with the femtosecond pulse laser through the container. Features.
　第９発明における微粒子の製造方法によれば、第１発明～第７発明の何れかにおいて、前記容器は、前記容器の開口部を覆う蓋を含むことを特徴とする。 According to the method for producing fine particles in the ninth invention, in any one of the first to seventh inventions, the container includes a lid that covers the opening of the container.
　第１０発明におけるコロイド溶液によれば、第１発明～第４発明の何れかにおける微粒子の製造方法により生成された前記微粒子と、前記微粒子が分散された溶媒と、を備えることを特徴とする。 According to the colloidal solution in the tenth invention, the colloidal solution comprises the fine particles produced by the method for producing fine particles according to any one of the first to fourth inventions, and a solvent in which the fine particles are dispersed.
　第１１発明におけるコロイド溶液によれば、第１０発明において、前記溶媒は、アルデヒド基を有する化合物を含むことを特徴とする。 According to the colloidal solution in the eleventh invention, in the tenth invention, the solvent contains a compound having an aldehyde group.
　第１発明～第９発明によれば、照射工程は、前駆体と、酸化抑制溶媒とを混合した溶液に対して、集光したフェムト秒パルスレーザーを照射する。このため、酸化抑制溶媒を利用して、レーザー照射に伴い生成された微粒子の酸化を抑制することができ、例えば微粒子の表面に任意の表面処理を行うことができる。これにより、微粒子の用途の拡大を図ることが可能となる。 According to the first to ninth inventions, in the irradiation step, a solution containing a mixture of a precursor and an oxidation-inhibiting solvent is irradiated with a focused femtosecond pulse laser. Therefore, by using the oxidation-inhibiting solvent, it is possible to suppress the oxidation of the fine particles generated due to laser irradiation, and, for example, it is possible to perform arbitrary surface treatment on the surfaces of the fine particles. This makes it possible to expand the uses of the fine particles.
　特に、第２発明によれば、前駆体は金属塩を含み、酸化抑制溶媒はアルコールを含む。このため、アルコールの酸化反応を利用して、金属塩に基づき生成された微粒子の酸化抑制を、容易に維持することができる。これにより、微粒子の経時に伴う品質の劣化を抑制することが可能となる。 In particular, according to the second invention, the precursor contains a metal salt, and the oxidation-inhibiting solvent contains alcohol. Therefore, by utilizing the oxidation reaction of alcohol, it is possible to easily maintain the suppression of oxidation of the fine particles generated based on the metal salt. This makes it possible to suppress deterioration in quality of the fine particles over time.
　特に、第３発明によれば、金属塩に含まれる金属イオンの酸化還元電位は、負を示す。このため、酸化し易い特徴を有する微粒子を照射工程により生成した場合においても、アルコールの酸化反応を利用して微粒子の酸化を抑制することができ、従来では生成することが困難とされていた微粒子を生成することができる。これにより、微粒子の用途のさらなる拡大を図ることが可能となる。 In particular, according to the third invention, the redox potential of the metal ions contained in the metal salt is negative. Therefore, even when fine particles with characteristics that are easily oxidized are generated by the irradiation process, the oxidation reaction of alcohol can be used to suppress the oxidation of the fine particles, which was previously considered difficult to generate. can be generated. This makes it possible to further expand the uses of the fine particles.
　特に、第４発明によれば、金属塩は、酸化還元電位が負を示す２種類以上の材料を含む。このため、酸化し易い特徴を有する合金の微粒子を生成した場合においても、アルコールの酸化反応を利用して微粒子の酸化を抑制することができ、従来では生成することが困難とされていた合金の微粒子を生成することができる。これにより、微粒子の用途のさらなる拡大を図ることが可能となる。 In particular, according to the fourth invention, the metal salt includes two or more types of materials whose redox potential is negative. Therefore, even when fine particles of alloys with characteristics that are easily oxidized are generated, the oxidation of the fine particles can be suppressed by using the oxidation reaction of alcohol. Fine particles can be generated. This makes it possible to further expand the uses of the fine particles.
　特に、第５発明によれば、酸化抑制溶媒は、アルコールのみを含む。このため、溶液内において、微粒子の酸化を促進させる要因を少なくすることができる。これにより、微粒子の品質低下の抑制を図ることが可能となる。 In particular, according to the fifth invention, the oxidation-inhibiting solvent contains only alcohol. Therefore, factors that promote oxidation of fine particles in the solution can be reduced. This makes it possible to suppress deterioration in the quality of the fine particles.
　特に、第６発明によれば、前駆体は、微粒子の中央径よりも大きい中央径を有する固体粒子を含む。このため、レーザー照射に伴い微粒子を生成する際、前駆体から生じる不要な残渣等を抑制することができる。これにより、純度の高い微粒子を形成することが可能となる。 In particular, according to the sixth invention, the precursor includes solid particles having a larger median diameter than the median diameter of the fine particles. Therefore, when generating fine particles with laser irradiation, unnecessary residues etc. generated from the precursor can be suppressed. This makes it possible to form fine particles with high purity.
　特に、第７発明によれば、前駆体は、有機金属錯体を含み、酸化抑制溶媒は、フェニル基を有する材料を含む。このため、レーザー照射に伴い生成された微粒子には、フェニル基に基づく炭素を含有させることができる。これにより、アルコール等に分散させた状態を維持しなくとも、微粒子の酸化を抑制することができる。これにより、酸化を抑制した微粒子の保管を、容易に実現することが可能となる。 In particular, according to the seventh invention, the precursor includes an organometallic complex, and the oxidation-inhibiting solvent includes a material having a phenyl group. Therefore, the fine particles generated by laser irradiation can contain carbon based on phenyl groups. As a result, oxidation of the fine particles can be suppressed without maintaining the dispersed state in alcohol or the like. This makes it possible to easily store fine particles with oxidation suppressed.
　特に、第８発明によれば、照射工程は、容器を介して、溶液に対してフェムト秒パルスレーザーを照射する。このため、溶液と大気との界面からフェムト秒パルスレーザーを照射する場合に比べて、アルコール等に起因する発火の可能性を抑制することができる。これにより、微粒子を製造する際の安全性を向上させることが可能となる。 In particular, according to the eighth invention, in the irradiation step, the solution is irradiated with a femtosecond pulse laser through the container. Therefore, the possibility of ignition caused by alcohol or the like can be suppressed compared to the case where femtosecond pulse laser is irradiated from the interface between the solution and the atmosphere. This makes it possible to improve safety when producing fine particles.
　特に、第９発明によれば、容器は、容器の開口部を覆う蓋を含む。このため、溶液の揮発を抑制することができる。これにより、微粒子を製造する際の経時変化を抑制することが可能となる。 In particular, according to the ninth invention, the container includes a lid that covers the opening of the container. Therefore, volatilization of the solution can be suppressed. This makes it possible to suppress changes over time during the production of fine particles.
　特に、第１０発明によれば、コロイド溶液は、微粒子が分散された溶媒を備える。これにより、微粒子の酸化を抑制した状態を保つコロイド溶液を提供することが可能となる。 In particular, according to the tenth invention, the colloidal solution includes a solvent in which fine particles are dispersed. This makes it possible to provide a colloidal solution that maintains a state in which oxidation of fine particles is suppressed.
　特に、第１１発明によれば、溶媒は、アルデヒド基を有する化合物を含む。このため、アルデヒド基の還元性を利用して、微粒子の酸化を抑制した状態を維持することができる。これにより、微粒子の品質を維持することが可能となる。 In particular, according to the eleventh invention, the solvent contains a compound having an aldehyde group. Therefore, by utilizing the reducing property of the aldehyde group, it is possible to maintain a state in which oxidation of the fine particles is suppressed. This makes it possible to maintain the quality of the fine particles.
図１は、本実施形態における微粒子の製造方法に用いられる製造装置の一例を示す模式斜視図である。FIG. 1 is a schematic perspective view showing an example of a manufacturing apparatus used in the method for manufacturing fine particles in this embodiment. 図２は、本実施形態における微粒子の製造方法の一例を示すフローチャートである。FIG. 2 is a flowchart illustrating an example of the method for producing fine particles in this embodiment.
　以下、本発明の実施形態としての微粒子の製造方法、及びコロイド溶液の一例について、図面を参照しながら説明する。 Hereinafter, a method for producing fine particles and an example of a colloidal solution as an embodiment of the present invention will be described with reference to the drawings.
（第１実施形態：微粒子、コロイド溶液）
　本実施形態における微粒子は、発電素子等の電子デバイスに用いられるほか、例えば医療、食品等の分野に用いられる。微粒子は、金属微粒子を含むほか、非金属微粒子を含んでもよい。微粒子は、例えば発電素子等のエネルギー分野や、導電性部品等の電子デバイス分野で用いることができる。上記のほか、微粒子は、例えば医薬品あるいは化粧品としての医療分野、複合材料の一部としての素材分野、食品等の分野で用いることができる。特に、微粒子の表面に対し、任意の表面処理（例えば被膜の形成）を行うことで、付加機能を有する微粒子を生成でき、様々な用途への展開が期待される。 (First embodiment: fine particles, colloidal solution)
The fine particles in this embodiment are used not only in electronic devices such as power generation elements, but also in fields such as medicine and food. The fine particles include not only metal fine particles but also non-metal fine particles. Fine particles can be used, for example, in the energy field, such as power generation elements, and in the electronic device field, such as conductive parts. In addition to the above, fine particles can be used, for example, in the medical field as pharmaceuticals or cosmetics, the material field as part of composite materials, and the food field. In particular, by performing arbitrary surface treatment (for example, forming a film) on the surface of the fine particles, fine particles having additional functions can be produced, which is expected to be used in a variety of applications.
　微粒子は、例えば１ｎｍ以上１００ｎｍ以下の粒子径を有する複数の粒子を含む。微粒子は、例えばメディアン径（中央径：Ｄ５０）が１ｎｍ以上１０ｎｍ以下の粒子径を有する粒子を含んでもよいほか、例えば平均粒径が１ｎｍ以上１０ｎｍ以下の粒子径を有する粒子を含んでもよい。メディアン径又は平均粒径は、例えば粒度分布計測器を用いることで、測定することができる。粒度分布計測器としては、例えば、動的光散乱法を用いた粒度分布計測器（例えばMalvern Panalytical 製ゼータサイザーUltra等）を用いればよい。 The fine particles include a plurality of particles having a particle diameter of, for example, 1 nm or more and 100 nm or less. The fine particles may include, for example, particles having a median diameter (median diameter: D50) of 1 nm or more and 10 nm or less, and may also include, for example, particles having an average particle diameter of 1 nm or more and 10 nm or less. The median diameter or average particle diameter can be measured, for example, using a particle size distribution meter. As the particle size distribution measuring device, for example, a particle size distribution measuring device using a dynamic light scattering method (for example, Zetasizer Ultra manufactured by Malvern Panalytical, etc.) may be used.
　微粒子は、単一原子により生成された粒子群を示すほか、例えばそれぞれ異なる種類の原子により生成された２種類以上の粒子を含む粒子群を示してもよい。微粒子は、例えば２種類以上の原子を含有する化合物（例えば合金）の粒子群を示してもよい。 In addition to indicating a particle group generated by a single atom, fine particles may also refer to a particle group including two or more types of particles, each of which is generated by a different type of atom, for example. The fine particles may represent, for example, a group of particles of a compound (for example, an alloy) containing two or more types of atoms.
　本実施形態におけるコロイド溶液は、微粒子と同様の分野にて用いられる。コロイド溶液は、例えば微粒子を含む２種類以上の物質が混合する状態を示す。コロイド溶液は、例えば微粒子が分散された溶媒を含む。 The colloidal solution in this embodiment is used in the same field as fine particles. A colloidal solution refers to a state in which two or more types of substances including, for example, fine particles are mixed. A colloidal solution includes, for example, a solvent in which fine particles are dispersed.
　コロイド溶液は、例えばアルコールを含む溶媒と、溶媒に分散された微粒子と、を備え、微粒子の表面は、溶媒に接する。即ち、微粒子の表面には、酸化膜が形成されておらず、金属の表面が直接溶媒に接する。このため、アルコールの酸化反応を利用して、微粒子の酸化を抑制することができ、例えば微粒子に任意の表面処理を行うことができる。これにより、微粒子の用途の拡大を図ることが可能となる。 A colloidal solution includes, for example, a solvent containing alcohol and fine particles dispersed in the solvent, and the surfaces of the fine particles are in contact with the solvent. That is, no oxide film is formed on the surface of the fine particles, and the metal surface is in direct contact with the solvent. Therefore, the oxidation reaction of alcohol can be used to suppress the oxidation of the fine particles, and, for example, the fine particles can be subjected to arbitrary surface treatment. This makes it possible to expand the uses of the fine particles.
　コロイド溶液は、例えば任意の容器に保存され、例えば窒素充填環境、減圧環境等のような酸素の介入を抑制した容器の中に保存される。この場合、微粒子の経時に伴う酸化を抑制し易くすることができる。これにより、微粒子の品質を維持し易くすることが可能となる。 The colloidal solution may be stored, for example, in any container, such as a container filled with nitrogen, a reduced pressure environment, etc., where oxygen interference is suppressed. In this case, oxidation of the fine particles over time can be easily suppressed. This makes it possible to easily maintain the quality of the fine particles.
　溶媒は、例えばエタノール、メタノール、１－プロパノール等のような１価を示すアルコールを含む。例えば溶媒がエタノールを含む場合、溶媒は、エタノールの酸化により生成されたアセトアルデヒド、及びアセトアルデヒドの酸化により生成された酢酸の少なくとも何れかを含んでもよい。なお溶媒は、例えば後述する酸化抑制溶媒と同じ材料を含んでもよい。 The solvent includes, for example, a monovalent alcohol such as ethanol, methanol, 1-propanol, and the like. For example, when the solvent contains ethanol, the solvent may contain at least one of acetaldehyde produced by oxidation of ethanol and acetic acid produced by oxidation of acetaldehyde. Note that the solvent may include, for example, the same material as the oxidation-inhibiting solvent described below.
　例えば溶媒は、アルデヒド基を有する化合物を含んでもよい。この場合、アルデヒド基の還元性を利用して、微粒子の酸化を抑制した状態を維持することができる。これにより、微粒子の品質を維持することが可能となる。 For example, the solvent may contain a compound having an aldehyde group. In this case, by utilizing the reducing properties of aldehyde groups, it is possible to maintain a state in which oxidation of the fine particles is suppressed. This makes it possible to maintain the quality of the fine particles.
　例えば微粒子は、１種類以上の卑金属の材料を含有する。この場合、コロイド溶液において、酸化し易い特徴を有する微粒子が溶媒に接した状態を保つことができ、微粒子の酸化を抑制することができる。これにより、微粒子の品質低下の抑制を図ることが可能となる。 For example, the fine particles contain one or more base metal materials. In this case, in the colloidal solution, fine particles having characteristics that are easily oxidized can be kept in contact with the solvent, and oxidation of the fine particles can be suppressed. This makes it possible to suppress deterioration in the quality of the fine particles.
　例えば微粒子は、同じ結晶構造を示す２種類以上の材料を含有する。この場合、合金の微粒子全体で結晶構造が同じ傾向を示すため、微粒子の安定化を図ることができる。これにより、微粒子の品質低下の抑制、及び微粒子の安定性向上を図ることが可能となる。 For example, fine particles contain two or more types of materials that exhibit the same crystal structure. In this case, since the crystal structure of the entire fine particles of the alloy tends to be the same, it is possible to stabilize the fine particles. This makes it possible to suppress deterioration in the quality of the fine particles and improve the stability of the fine particles.
（製造装置１００）
　次に、本実施形態における微粒子の製造方法に用いられる製造装置１００の一例について説明する。図１は、本実施形態における製造装置１００の一例を示す模式斜視図である。 (Manufacturing equipment 100)
Next, an example of the manufacturing apparatus 100 used in the method of manufacturing fine particles in this embodiment will be described. FIG. 1 is a schematic perspective view showing an example of a manufacturing apparatus 100 in this embodiment.
　製造装置１００は、例えば図１に示すように、レーザー装置１と、レンズ２と、容器３と、溶液４とを備える。製造装置１００は、例えば１つのレーザー装置１に対し、複数の容器３及び溶液４を備えてもよい。 The manufacturing apparatus 100 includes, for example, a laser device 1, a lens 2, a container 3, and a solution 4, as shown in FIG. The manufacturing apparatus 100 may include a plurality of containers 3 and solutions 4 for one laser device 1, for example.
　＜レーザー装置１＞
  レーザー装置１は、例えば１０－１５秒程度の時間幅を有するパルスレーザーを出射する。レーザー装置１として、例えば下記のような特性を示し、例えばCOHERENT社製のAstrella等のフェムト秒パルスレーザーを用いることができる。
　発振波長：８００ｎｍ±２０ｎｍ
　パルス幅：１００ｆｓ
　エネルギー：５－９ｍＪ
　繰り返し周波数：１００Ｈｚ（出力０．５－０．９Ｗ） <Laser device 1>
The laser device 1 emits a pulsed laser having a time width of, for example, about 10 −15 seconds. As the laser device 1, for example, a femtosecond pulse laser such as Astrella manufactured by COHERENT, which exhibits the following characteristics, can be used.
Laser wavelength: 800nm±20nm
Pulse width: 100fs
Energy: 5-9mJ
Repetition frequency: 100Hz (output 0.5-0.9W)
　上記のほか、レーザー装置１として、例えばSpectra Physics社製のSpitfire Pro等が用いられ、用途に応じて任意に選択することができる。なお、レーザー装置１から出射されるレーザーは、数ｍＪ程度のエネルギーであり、例えばレーザー加工等に用いられるような数μＪ程度のエネルギーでは、微粒子の効率的な生成が難しい。 In addition to the above, the laser device 1 may be, for example, Spitfire Pro manufactured by Spectra Physics, and can be arbitrarily selected depending on the application. Note that the laser emitted from the laser device 1 has an energy of about several mJ, and it is difficult to efficiently generate fine particles with energy of about several μJ, which is used for example in laser processing.
　＜レンズ２＞
　レンズ２は、レーザー装置１から出射されたレーザーを集光する。レンズ２を用いることで、特定の領域に対して光強度を高めることができる。特に、レンズ２を用いることで、溶液４の界面よりも溶液４の内部にレーザーを集光することができる。レンズ２として、集光レンズ等の公知のレンズが用いられる。レンズ２を介して集光したレーザーを溶液４に照射することで、微粒子の生成効率を向上させることができる。 <Lens 2>
The lens 2 condenses the laser emitted from the laser device 1. By using the lens 2, the light intensity can be increased in a specific area. In particular, by using the lens 2, the laser can be focused inside the solution 4 rather than at the interface of the solution 4. As the lens 2, a known lens such as a condenser lens is used. By irradiating the solution 4 with a laser focused through the lens 2, it is possible to improve the generation efficiency of fine particles.
　＜容器３＞
　容器３は、溶液４を収める。容器３として、透明な材料が用いられ、例えば溶融石英キュベットが用いられる。容器３として、例えば４００ｎｍ付近における波長の吸収率に比べて、８００ｎｍ付近における波長の吸収率が低い材料が用いられる。この場合、容器３を介してレーザーを照射する際、微粒子の生成効率の低下を抑制することができる。 <Container 3>
Container 3 contains solution 4. A transparent material is used as the container 3, for example a fused silica cuvette. For example, a material having a lower absorption rate at a wavelength around 800 nm than around 400 nm is used as the container 3. In this case, when irradiating the laser through the container 3, it is possible to suppress a decrease in the production efficiency of fine particles.
　容器３は、例えば開口部３ａを覆う蓋３１を含んでもよい。この場合、アルコールの揮発を抑制することができる。これにより、微粒子を製造する際の経時変化を抑制することが可能となる。 The container 3 may include, for example, a lid 31 that covers the opening 3a. In this case, volatilization of alcohol can be suppressed. This makes it possible to suppress changes over time during the production of fine particles.
　蓋３１として、例えば容器３と同様の材料が用いられるほか、アルコール耐性を有する材料が用いられてもよい。蓋３１の形状は、板状のほか、例えば開口部３ａに嵌合するための縁を有する形状でもよい。 For the lid 31, for example, the same material as the container 3 may be used, or a material that is resistant to alcohol may be used. The shape of the lid 31 may be in addition to a plate shape, for example, a shape having an edge for fitting into the opening 3a.
　＜溶液４＞
　溶液４は、微粒子の前駆体と、酸化抑制溶媒とを混合した液体を示す。酸化抑制溶媒は、微粒子の酸化を抑制する。溶液４に対してレーザーが照射されることで、微粒子が生成される。前駆体は、例えば金属塩を含む。また、酸化抑制溶媒は、例えばアルコールを含む。 <Solution 4>
Solution 4 is a liquid mixture of a fine particle precursor and an oxidation-inhibiting solvent. The oxidation-inhibiting solvent inhibits oxidation of the fine particles. Fine particles are generated by irradiating the solution 4 with a laser. Precursors include, for example, metal salts. Further, the oxidation-inhibiting solvent includes, for example, alcohol.
　溶液４における金属塩の濃度は、例えば１．０×１０－５ｍоｌ・ｄｍ－３以上１．０×１０－１ｍоｌ・ｄｍ－３以下程度であり、生成される微粒子の用途に応じて任意に設定できる。 The concentration of the metal salt in the solution 4 is, for example, about 1.0×10 −5 mol·dm −3 or more and 1.0×10 −1 mol·dm −3 or less, and can be set arbitrarily depending on the purpose of the generated fine particles. Can be set to
　金属塩は、金属イオンを含む公知の化合物を含有し、用途に応じて任意の材料を含有させることができる。金属塩は、１種以上の材料を含有する。例えば金属塩が２種以上の材料を含有する場合、各材料を含有した合金の微粒子を生成することができる。金属塩として、例えばＨＡｕＣｌ４・３Ｈ２Ｏ、Ｈ２ＰｔＣｌ６・６Ｈ２Ｏ等の公知の金属塩が用いられる。 The metal salt contains a known compound containing a metal ion, and can contain any material depending on the purpose. Metal salts contain one or more materials. For example, when the metal salt contains two or more types of materials, fine particles of an alloy containing each material can be produced. As the metal salt, known metal salts such as HAuCl 4.3H 2 O and H 2 PtCl 6.6H 2 O are used.
　例えば、金属塩に含まれる金属イオンの酸化還元電位は、負を示してもよい。この場合、金属塩として、例えばＦｅＣｌ３・６Ｈ２Ｏや、ＮｉＣｌ２・６Ｈ２Ｏ等の卑金属を含む材料が用いられる。ここで、酸化還元電位が負の金属イオンを含む金属塩を用いた場合、微粒子の生成に伴い酸化する懸念が挙げられる。これに対し、本実施形態によれば、酸化抑制溶媒に含まれるアルコールの酸化反応を利用して、微粒子の酸化反応を抑制することができる。これにより、従来では生成することが困難とされていた微粒子を生成することができる。従って、微粒子の用途のさらなる拡大を図ることが可能となる。 For example, the redox potential of the metal ion contained in the metal salt may be negative. In this case, a material containing a base metal such as FeCl 3 .6H 2 O or NiCl 2 .6H 2 O is used as the metal salt. Here, when a metal salt containing a metal ion with a negative redox potential is used, there is a concern that oxidation may occur as fine particles are generated. In contrast, according to the present embodiment, the oxidation reaction of the fine particles can be suppressed by utilizing the oxidation reaction of the alcohol contained in the oxidation-inhibiting solvent. As a result, it is possible to generate fine particles that have been difficult to generate in the past. Therefore, it becomes possible to further expand the uses of the fine particles.
　金属塩は、例えば２種類以上の材料を含む。例えば金属塩は、酸化還元電位が負を示す材料を少なくとも１種類含んでもよい。この場合においても、上記と同様に、酸化抑制溶媒に含まれるアルコールの酸化反応を利用して、２種類以上の材料を含有する微粒子の酸化反応を抑制することができる。これにより、従来では生成することが困難とされていた微粒子を生成することができる。従って、微粒子の用途のさらなる拡大を図ることが可能となる。 The metal salt includes, for example, two or more types of materials. For example, the metal salt may include at least one material having a negative redox potential. In this case as well, similarly to the above, the oxidation reaction of the alcohol contained in the oxidation-inhibiting solvent can be used to suppress the oxidation reaction of the fine particles containing two or more types of materials. As a result, it is possible to generate fine particles that have been difficult to generate in the past. Therefore, it becomes possible to further expand the uses of the fine particles.
　例えば金属塩は、酸化還元電位が負を示す２種類以上の材料を含んでもよい。この場合、金属塩として、例えばＦｅＣｌ３・６Ｈ２Ｏ、及びＮｉＣｌ２・６Ｈ２Ｏのような２種類の材料が用いられる。ここで、酸化し易い特徴を有する合金の微粒子を生成した場合においても、酸化抑制溶媒に含まれるアルコールの酸化反応を利用して、微粒子の酸化を抑制することができる。これにより、従来では生成することが困難とされていた合金の微粒子を生成することができる。従って、微粒子の用途のさらなる拡大を図ることが可能となる。 For example, the metal salt may include two or more types of materials that exhibit negative redox potential. In this case, two types of materials are used as metal salts, such as FeCl 3 .6H 2 O and NiCl 2 .6H 2 O. Here, even when fine particles of an alloy having characteristics that are easily oxidized are produced, oxidation of the fine particles can be suppressed by utilizing the oxidation reaction of alcohol contained in the oxidation-inhibiting solvent. As a result, it is possible to generate alloy fine particles that have been difficult to generate in the past. Therefore, it becomes possible to further expand the uses of the fine particles.
　なお、「酸化還元電位」は、例えば分析化学データブック（丸善出版）等に記載された公知の値を示す。また、「卑金属」は、金属イオンの酸化還元電位が負の値として分類された金属を示し、例えばリチウム、カリウム、カルシウム、ナトリウム、マグネシウム、アルミニウム、亜鉛、鉄、ニッケル、錫、鉛を示す。 Note that the "oxidation-reduction potential" indicates a known value described in, for example, the Analytical Chemistry Data Book (Maruzen Publishing). Further, "base metal" refers to metals whose metal ions are classified as having a negative redox potential, such as lithium, potassium, calcium, sodium, magnesium, aluminum, zinc, iron, nickel, tin, and lead.
　例えば金属塩は、同じ結晶構造を示す２種類以上の材料を含有してもよい。この場合、生成された合金の微粒子全体で、結晶構造が同じ傾向を示すため、微粒子の安定化を図ることができる。これにより、微粒子の安定性向上を図ることが可能となる。 For example, the metal salt may contain two or more types of materials exhibiting the same crystal structure. In this case, the crystal structure of the entire fine particles of the produced alloy tends to be the same, so that the fine particles can be stabilized. This makes it possible to improve the stability of the fine particles.
　例えば鉄、ナトリウム、及びカリウムの結晶構造は、体心立方格子を示す。このため、金属塩として、鉄、ナトリウム、及びカリウムの少なくとも２種以上を含む材料を含有することで、生成された合金の微粒子全体で、結晶構造が同じ傾向を示す。また、例えばニッケル、アルミニウム、及びカルシウムの結晶構造は、面心立方格子を示す。このため、金属塩として、ニッケル、アルミニウム、及びカルシウムの少なくとも２種類以上を含む材料を含有することで、生成された合金の微粒子全体で、結晶構造が同じ傾向を示す。 For example, the crystal structures of iron, sodium, and potassium exhibit a body-centered cubic lattice. Therefore, by containing a material containing at least two of iron, sodium, and potassium as a metal salt, the entire fine particles of the produced alloy tend to have the same crystal structure. Also, for example, the crystal structures of nickel, aluminum, and calcium exhibit face-centered cubic lattices. Therefore, by containing a material containing at least two of nickel, aluminum, and calcium as a metal salt, the crystal structure of the entire fine particles of the produced alloy tends to be the same.
　酸化抑制溶媒は、ヒドロキシ基を有する公知のアルコールを含む。酸化抑制溶媒は、例えばエタノール、メタノール、１－プロパノール等のような、１価を示すアルコールを含んでもよい。酸化抑制溶媒は、例えばアルデヒド基、及びカルボキシル基の少なくとも何れかを有する化合物を含んでもよい。 The oxidation-inhibiting solvent includes a known alcohol having a hydroxy group. The oxidation-inhibiting solvent may include a monohydric alcohol, such as ethanol, methanol, 1-propanol, and the like. The oxidation-inhibiting solvent may include, for example, a compound having at least one of an aldehyde group and a carboxyl group.
　例えば酸化抑制溶媒は、アルコールのみを含んでもよい。この場合、溶液４内において、生成された微粒子の酸化を促進させる要因を少なくすることができる。これにより、微粒子の品質低下の抑制を図ることが可能となる。 For example, the oxidation-inhibiting solvent may contain only alcohol. In this case, factors that promote oxidation of the generated fine particles in the solution 4 can be reduced. This makes it possible to suppress deterioration in the quality of the fine particles.
（第１実施形態：微粒子の製造方法）
　次に、本実施形態における微粒子の製造方法の一例について説明する。図２は、本実施形態における微粒子の製造方法の一例を示すフローチャートである。微粒子の製造方法は、例えば図２に示すように、溶液形成工程Ｓ１１０と、照射工程Ｓ１２０とを備える。 (First embodiment: method for producing fine particles)
Next, an example of a method for manufacturing fine particles in this embodiment will be described. FIG. 2 is a flowchart illustrating an example of the method for producing fine particles in this embodiment. For example, as shown in FIG. 2, the method for producing fine particles includes a solution forming step S110 and an irradiation step S120.
　＜溶液形成工程Ｓ１１０＞
　溶液形成工程Ｓ１１０は、前駆体と、酸化抑制溶媒とを混合した溶液４を、容器３内に形成する。溶液形成工程Ｓ１１０では、例えば前駆体は金属塩を含み、酸化抑制溶媒はアルコールを含む。金属塩及びアルコールとして、例えば上述した材料が用いられる。 <Solution formation step S110>
In the solution forming step S110, a solution 4 in which a precursor and an oxidation-inhibiting solvent are mixed is formed in the container 3. In the solution forming step S110, for example, the precursor contains a metal salt, and the oxidation-inhibiting solvent contains alcohol. For example, the above-mentioned materials are used as the metal salt and alcohol.
　溶液形成工程Ｓ１１０では、例えば容器３内に、前駆体及び酸化抑制溶媒を入れたあと、撹拌子を用いて撹拌することで、溶液４を形成することができる。例えば溶液形成工程Ｓ１１０では、容器３内に前駆体を入れたあと、酸化抑制溶媒を段階的に入れてもよい。この場合、前駆体の濃度を容易に調整することができる。上記のほか、例えば溶液形成工程Ｓ１１０では、例えば準備用の容器に、前駆体及び酸化抑制溶媒を入れて溶液４を形成し、容器３内に移してもよい。 In the solution forming step S110, the solution 4 can be formed by, for example, placing the precursor and the oxidation-inhibiting solvent in the container 3 and then stirring them using a stirrer. For example, in the solution forming step S110, after the precursor is placed in the container 3, the oxidation-inhibiting solvent may be added in stages. In this case, the concentration of the precursor can be easily adjusted. In addition to the above, for example, in the solution forming step S110, the precursor and the oxidation-inhibiting solvent may be put into a preparation container to form the solution 4, and the solution 4 may be transferred into the container 3.
　＜照射工程Ｓ１２０＞
　照射工程Ｓ１２０は、フェムト秒パルスレーザーを集光し、溶液４に対して照射する。照射工程Ｓ１２０では、例えばレーザー装置１から出射されたフェムト秒パルスレーザーが溶液４に照射されると、溶液４内の溶媒分子（例えば酸化抑制溶媒がエタノールの場合はエタノール分子）が分解されてラジカルが生成される。そして、生成されたラジカルのうち自由電子により、前駆体に含まれる金属イオンが還元され、微粒子が生成される。このように、溶液４にレーザーを照射することにより、前駆体に基づく微粒子が生成される。 <Irradiation step S120>
In the irradiation step S120, a femtosecond pulse laser is focused and the solution 4 is irradiated. In the irradiation step S120, for example, when the solution 4 is irradiated with the femtosecond pulse laser emitted from the laser device 1, the solvent molecules (for example, ethanol molecules when the oxidation-inhibiting solvent is ethanol) in the solution 4 are decomposed and radicals are generated. is generated. Then, metal ions contained in the precursor are reduced by free electrons among the generated radicals, and fine particles are generated. In this way, by irradiating the solution 4 with a laser, fine particles based on the precursor are generated.
　例えば、本実施形態における照射工程Ｓ１２０では、金属塩を含む前駆体と、アルコールを含む酸化抑制溶媒とを混合した溶液４に対してレーザーを照射する。この際、アルコールの酸化によりアルデヒド基を有する化合物が生成される。即ち、アルコールの酸化反応によって、生成された微粒子の酸化反応を抑制することができる。このため、微粒子の表面に酸化被膜が形成されることを抑制できる。 For example, in the irradiation step S120 in this embodiment, a laser is irradiated onto the solution 4 that is a mixture of a precursor containing a metal salt and an oxidation-inhibiting solvent containing an alcohol. At this time, a compound having an aldehyde group is produced by oxidation of the alcohol. That is, the oxidation reaction of the fine particles generated by the oxidation reaction of alcohol can be suppressed. Therefore, formation of an oxide film on the surface of the fine particles can be suppressed.
　照射工程Ｓ１２０は、例えば容器３を介して、溶液４に対してレーザーを照射してもよい。この場合、溶液４と大気との界面からレーザーを照射する場合に比べて、アルコール等に起因する発火の可能性を抑制することができる。これにより、微粒子を製造する際の安全性を向上させることが可能となる。 In the irradiation step S120, the solution 4 may be irradiated with a laser through the container 3, for example. In this case, the possibility of ignition caused by alcohol or the like can be suppressed compared to the case where the laser is irradiated from the interface between the solution 4 and the atmosphere. This makes it possible to improve safety when producing fine particles.
　照射工程Ｓ１２０は、例えば容器３の開口部３ａを覆う蓋３１を設けた状態で、溶液４に対してレーザーを照射してもよい。この場合、溶液４の揮発を抑制することができる。これにより、微粒子を製造する際の経時変化を抑制することが可能となる。 In the irradiation step S120, the solution 4 may be irradiated with a laser, for example, with the lid 31 covering the opening 3a of the container 3 provided. In this case, volatilization of the solution 4 can be suppressed. This makes it possible to suppress changes over time during the production of fine particles.
　これにより、本実施形態における微粒子、及びコロイド溶液が生成される。なお、照射工程Ｓ１２０のあと、例えば被膜形成工程Ｓ１３０を実施してもよい。被膜形成工程Ｓ１３０は、例えば公知の相間移動法等を用いて、任意の材料を含む被膜を微粒子の表面に形成する。 As a result, fine particles and a colloidal solution in this embodiment are generated. Note that, after the irradiation step S120, for example, a film forming step S130 may be performed. In the film forming step S130, a film containing an arbitrary material is formed on the surface of the fine particles using, for example, a known phase transfer method.
　本実施形態によれば、照射工程Ｓ１２０は、前駆体と、酸化抑制溶媒とを混合した溶液４に対して、集光したフェムト秒パルスレーザーを照射する。このため、酸化抑制溶媒を利用して、レーザー照射に伴い生成された微粒子の酸化を抑制することができ、例えば微粒子の表面に任意の表面処理（例えば被膜の形成）を容易に行うことができる。これにより、微粒子の用途の拡大を図ることが可能となる。 According to the present embodiment, in the irradiation step S120, the solution 4 in which the precursor and the oxidation-inhibiting solvent are mixed is irradiated with a focused femtosecond pulse laser. Therefore, by using an oxidation-inhibiting solvent, it is possible to suppress the oxidation of fine particles generated due to laser irradiation, and, for example, it is possible to easily perform arbitrary surface treatment (for example, forming a film) on the surface of fine particles. . This makes it possible to expand the uses of the fine particles.
　また、本実施形態によれば、前駆体は金属塩を含み、酸化抑制溶媒はアルコールを含む。このため、アルコールの酸化反応を利用して、金属塩に基づき生成された微粒子の酸化抑制を、容易に維持することができる。これにより、微粒子の経時に伴う品質の劣化を抑制することが可能となる。 Furthermore, according to the present embodiment, the precursor includes a metal salt, and the oxidation-inhibiting solvent includes alcohol. Therefore, by utilizing the oxidation reaction of alcohol, it is possible to easily maintain the suppression of oxidation of the fine particles generated based on the metal salt. This makes it possible to suppress deterioration in quality of the fine particles over time.
　また、本実施形態によれば、金属塩に含まれる金属イオンの酸化還元電位は、負を示す。このため、酸化し易い特徴を有する微粒子を照射工程Ｓ１２０により生成した場合においても、アルコールの酸化反応を利用して微粒子の酸化を抑制することができ、従来では生成することが困難とされていた微粒子を生成することができる。これにより、微粒子の用途のさらなる拡大を図ることが可能となる。 Furthermore, according to the present embodiment, the redox potential of the metal ions contained in the metal salt is negative. Therefore, even when fine particles with characteristics that are easily oxidized are generated in the irradiation step S120, the oxidation of the fine particles can be suppressed by using the oxidation reaction of alcohol, which was previously considered difficult to generate. Fine particles can be generated. This makes it possible to further expand the uses of the fine particles.
　また、本実施形態によれば、金属塩は、酸化還元電位が負を示す２種類以上の材料を含む。このため、酸化し易い特徴を有する合金の微粒子を生成した場合においても、アルコールの酸化反応を利用して微粒子の酸化を抑制することができ、従来では生成することが困難とされていた合金の微粒子を生成することができる。これにより、微粒子の用途のさらなる拡大を図ることが可能となる。 Furthermore, according to the present embodiment, the metal salt includes two or more types of materials whose redox potential is negative. Therefore, even when fine particles of alloys with characteristics that are easily oxidized are generated, the oxidation of the fine particles can be suppressed by using the oxidation reaction of alcohol. Fine particles can be generated. This makes it possible to further expand the uses of the fine particles.
　また、本実施形態によれば、酸化抑制溶媒は、アルコールのみを含む。このため、溶液４内において、微粒子の酸化を促進させる要因を少なくすることができる。これにより、微粒子の品質低下の抑制を図ることが可能となる。 Furthermore, according to the present embodiment, the oxidation-inhibiting solvent contains only alcohol. Therefore, in the solution 4, factors that promote oxidation of the fine particles can be reduced. This makes it possible to suppress deterioration in the quality of the fine particles.
　また、本実施形態によれば、照射工程Ｓ１２０は、容器３を介して、溶液４に対してフェムト秒パルスレーザーを照射する。このため、溶液４と大気との界面からフェムト秒パルスレーザーを照射する場合に比べて、アルコール等に起因する発火の可能性を抑制することができる。これにより、微粒子を製造する際の安全性を向上させることが可能となる。 Furthermore, according to the present embodiment, in the irradiation step S120, the solution 4 is irradiated with a femtosecond pulse laser through the container 3. Therefore, the possibility of ignition caused by alcohol or the like can be suppressed compared to the case where femtosecond pulse laser is irradiated from the interface between the solution 4 and the atmosphere. This makes it possible to improve safety when producing fine particles.
　また、本実施形態によれば、容器３は、容器３の開口部３ａを覆う蓋３１を含む。このため、溶液４の揮発を抑制することができる。これにより、微粒子を製造する際の経時変化を抑制することが可能となる。 Furthermore, according to the present embodiment, the container 3 includes a lid 31 that covers the opening 3a of the container 3. Therefore, volatilization of the solution 4 can be suppressed. This makes it possible to suppress changes over time during the production of fine particles.
　また、本実施形態によれば、コロイド溶液は、微粒子が分散された溶媒を備える。これにより、微粒子の酸化を抑制した状態を保つコロイド溶液を提供することが可能となる。 Furthermore, according to this embodiment, the colloidal solution includes a solvent in which fine particles are dispersed. This makes it possible to provide a colloidal solution that maintains a state in which oxidation of fine particles is suppressed.
　また、本実施形態によれば、溶媒は、アルデヒド基を有する化合物を含む。このため、アルデヒド基の還元性を利用して、微粒子の酸化を抑制した状態を維持することができる。これにより、微粒子の品質を維持することが可能となる。 Further, according to this embodiment, the solvent includes a compound having an aldehyde group. Therefore, by utilizing the reducing property of the aldehyde group, it is possible to maintain a state in which oxidation of the fine particles is suppressed. This makes it possible to maintain the quality of the fine particles.
（第２実施形態：微粒子の製造方法）
　次に、第２実施形態における微粒子の製造方法の一例を説明する。上述した実施形態と、本実施形態との違いは、固体粒子を用いて微粒子を生成する点である。なお、上述した構成と同様の内容については、説明を省略する。 (Second embodiment: method for producing fine particles)
Next, an example of a method for manufacturing fine particles in the second embodiment will be described. The difference between the embodiments described above and this embodiment is that fine particles are generated using solid particles. Note that the description of the same contents as the above-mentioned configuration will be omitted.
　本実施形態における微粒子の製造方法では、前駆体は、固体粒子を含む。固体粒子は、例えば５００μｍ以下の有限値の粒子径を有する複数の粒子を含む。固体粒子は、生成される微粒子の中央径よりも大きい中央径を有する。固体粒子は、例えば５０ｎｍ以上１００μｍ程度の中央径を有する。 In the method for producing fine particles in this embodiment, the precursor includes solid particles. The solid particles include a plurality of particles having a finite particle diameter of, for example, 500 μm or less. The solid particles have a median diameter that is larger than the median diameter of the fine particles produced. The solid particles have a median diameter of, for example, 50 nm or more and about 100 μm.
　固体粒子の材料は、生成する微粒子の材料に直接反映されるため、生成する微粒子の種類に応じて、任意に設定することができる。例えば固体粒子として金が用いられる場合、生成される微粒子は、金を含有する。この際、上述した金属塩とは異なり、固体粒子には塩素等のような微粒子に含有されない材料を含まない。このため、微粒子の生成に伴い不要となる材料の発生を抑制することができる。 The material of the solid particles is directly reflected in the material of the fine particles to be generated, so it can be arbitrarily set depending on the type of fine particles to be generated. For example, when gold is used as the solid particles, the fine particles produced contain gold. At this time, unlike the metal salt described above, the solid particles do not contain materials that are not contained in fine particles, such as chlorine. Therefore, generation of unnecessary material due to the generation of fine particles can be suppressed.
　なお、上述した実施形態と同様に、酸化抑制溶媒は、アルコールを含んでもよい。この場合にも上述した実施形態と同様に、生成された微粒子の酸化を抑制することができる。 Note that, similar to the embodiments described above, the oxidation-inhibiting solvent may include alcohol. In this case as well, as in the embodiment described above, oxidation of the generated fine particles can be suppressed.
　例えば溶液形成工程Ｓ１１０及び照射工程Ｓ１２０では、上述した各条件に加え、溶液４を攪拌した状態で実施してもよい。これにより、固体粒子を溶液４内に分散した状態を保つことができ、微粒子の生成効率を向上させることが可能となる。 For example, in the solution forming step S110 and the irradiation step S120, in addition to the above-mentioned conditions, the solution 4 may be stirred. Thereby, the solid particles can be maintained in a dispersed state in the solution 4, and it is possible to improve the production efficiency of fine particles.
　本実施形態によれば、前駆体は、微粒子の中央径よりも大きい中央径を有する固体粒子を含む。このため、レーザー照射に伴い微粒子を生成する際、前駆体から生じる不要な残渣等を抑制することができる。これにより、純度の高い微粒子を形成することが可能となる。 According to this embodiment, the precursor includes solid particles having a median diameter larger than the median diameter of the microparticles. Therefore, when generating fine particles with laser irradiation, unnecessary residues etc. generated from the precursor can be suppressed. This makes it possible to form fine particles with high purity.
（第３実施形態：微粒子の製造方法）
　次に、第３実施形態における微粒子の製造方法の一例を説明する。上述した実施形態と、本実施形態との違いは、有機金属錯体を用いて微粒子を生成する点である。なお、上述した構成と同様の内容については、説明を省略する。 (Third embodiment: method for producing fine particles)
Next, an example of a method for manufacturing fine particles in the third embodiment will be described. The difference between the embodiments described above and this embodiment is that fine particles are generated using an organometallic complex. Note that the description of the same contents as the above-mentioned configuration will be omitted.
　本実施形態における微粒子の製造方法では、前駆体は、有機金属錯体を含む。また、酸化抑制溶媒は、フェニル基を有する材料を含む。 In the method for producing fine particles in this embodiment, the precursor includes an organometallic complex. Further, the oxidation-inhibiting solvent includes a material having a phenyl group.
　有機金属錯体として、例えばＣＨ３Ｌｉ（メチルリチウム）、ＣＨ３ＣＨ２ＭｇＢｒ（エチルグリニャール）等のアルキル錯体や、Ｆｅ（Ｃ５Ｈ５）２（フェロセン）等の芳香族の錯体、Ｃｕ（Ｃ５Ｈ７Ｏ２）２（銅アセチルアセトナート）等のアセチルアセトン錯体が用いられるほか、公知の材料を用いることができる。 Examples of organometallic complexes include alkyl complexes such as CH 3 Li (methyl lithium) and CH 3 CH 2 MgBr (ethyl Grignard), aromatic complexes such as Fe (C 5 H 5 ) 2 (ferrocene), and Cu (C In addition to an acetylacetone complex such as 5 H 7 O 2 ) 2 (copper acetylacetonate), known materials can be used.
　フェニル基を有する材料として、例えばベンゼン、トルエン等が用いられる。 For example, benzene, toluene, etc. are used as the material having a phenyl group.
　本実施形態によれば、前駆体は、有機金属錯体を含み、酸化抑制溶媒は、フェニル基を有する材料を含む。このため、レーザー照射に伴い生成された微粒子には、フェニル基に基づく炭素を含有させることができる。これにより、アルコール等に分散させた状態を維持しなくとも、微粒子の酸化を抑制することができる。これにより、酸化を抑制した微粒子の保管を、容易に実現することが可能となる。 According to this embodiment, the precursor includes an organometallic complex, and the oxidation-inhibiting solvent includes a material having a phenyl group. Therefore, the fine particles generated by laser irradiation can contain carbon based on phenyl groups. As a result, oxidation of the fine particles can be suppressed without maintaining the dispersed state in alcohol or the like. This makes it possible to easily store fine particles with oxidation suppressed.
　上述した微粒子の製造方法により生成された微粒子、及びコロイド溶液は、例えば以下の用途が期待できる。例えば人工光合成の研究においては、使用されている微粒子の材料としてこれまで複数の提案があり、金、白金、金と銀の合金が挙げられる。これらの事例に、上述した微粒子を適用することで、人工光合成の特性を最適化することの変数となり得る。また、同様に積層セラミックコンデンサや電極等の電子部品に適用することも可能であり、現在、研究されている微粒子の材料としてはニッケルや、バリウム・酸化チタン（ＢａＴｉＯ３）などがある。上記のように、微粒子に期待される用途は多岐に亘る一方で、微粒子が酸化し易い等の事情により、微粒子の機能を十分に発揮できない可能性がある。これに対し、上述した微粒子の製造方法、及びコロイド溶液では、表面の酸化が抑制されており、微粒子の表面に任意の表面処理を行うことができる。これにより、微粒子の用途の拡大を図ることが可能となる。 The fine particles and colloidal solution produced by the above-described fine particle manufacturing method can be expected to have the following uses, for example. For example, in research on artificial photosynthesis, there have been several proposals as materials for the microparticles used, including gold, platinum, and gold-silver alloys. By applying the above-mentioned fine particles to these cases, they can become a variable for optimizing the characteristics of artificial photosynthesis. In addition, it is also possible to similarly apply it to electronic components such as multilayer ceramic capacitors and electrodes, and materials for fine particles currently being researched include nickel and barium/titanium oxide (BaTiO 3 ). As mentioned above, while a wide variety of applications are expected for fine particles, there is a possibility that the functions of fine particles cannot be fully demonstrated due to circumstances such as the tendency of fine particles to oxidize. In contrast, in the method for producing fine particles and the colloidal solution described above, oxidation of the surface is suppressed, and any surface treatment can be performed on the surface of the fine particles. This makes it possible to expand the uses of the fine particles.
　なお、上述した微粒子の製造方法により生成された微粒子は、例えばニッケル、白金、金、チタン等の公知の金属原子を含有する。微粒子は、例えば２種類以上の任意の原子を含有してもよい。微粒子は、例えばペロブスカイト構造を示してもよい。微粒子は、例えばチタン酸バリウム（ＢａＴｉＯ３）、チタン酸ストロンチウム（ＳｒＴｉＯ３）、チタン酸カルシウム（ＣａＴｉＯ３）、チタン酸鉛（ＰｂＴｉＯ３）、チタン酸錫（ＳｎＴｉＯ３）、チタン酸カドミウム（ＣｄＴｉＯ３）、及びジルコン酸ストロンチウム（ＳｒＺｒＯ３）の少なくとも何れかを含んでもよい。 Note that the fine particles produced by the above-described fine particle manufacturing method contain known metal atoms such as nickel, platinum, gold, titanium, and the like. The fine particles may contain, for example, two or more types of arbitrary atoms. The fine particles may exhibit, for example, a perovskite structure. The fine particles include, for example, barium titanate (BaTiO 3 ), strontium titanate (SrTiO 3 ), calcium titanate (CaTiO 3 ), lead titanate (PbTiO 3 ), tin titanate (SnTiO 3 ), and cadmium titanate (CdTiO 3 ) . ), and strontium zirconate (SrZrO 3 ).
　微粒子は、例えば２種類以上の金属原子を組合せた固溶体を示してもよい。この場合、固溶体を示さない微粒子と比べて、微粒子の部分的な状態変化や化学変化が起き難い。これにより、微粒子のさらなる安定性向上を図ることが可能となる。固溶体を示す微粒子に含有される金属原子の組合せの例としては、ニッケルと白金との組合せ、ニッケルとルテニウムとの組合せ、ニッケルとロジウムとの組合せ、ニッケルとパラジウムとの組合せ、ニッケルとイリジウムとの組合せ等が挙げられる。固溶体を示す微粒子に含有される金属原子の組合せとして、例えば混合エンタルピーが０以下となる金属原子の組合せが挙げられる。 The fine particles may represent, for example, a solid solution in which two or more types of metal atoms are combined. In this case, compared to fine particles that do not exhibit a solid solution, local state changes and chemical changes in the fine particles are less likely to occur. This makes it possible to further improve the stability of the fine particles. Examples of combinations of metal atoms contained in fine particles exhibiting a solid solution include a combination of nickel and platinum, a combination of nickel and ruthenium, a combination of nickel and rhodium, a combination of nickel and palladium, and a combination of nickel and iridium. Examples include combinations. Examples of the combination of metal atoms contained in the fine particles exhibiting a solid solution include a combination of metal atoms such that the enthalpy of mixing is 0 or less.
　微粒子は、例えば２種類の金属原子を組合せた共晶体を示してもよい。この場合、共晶体を示さない微粒子と比べて、微粒子の安定性を向上させることができる。 The fine particles may represent, for example, a eutectic in which two types of metal atoms are combined. In this case, the stability of the fine particles can be improved compared to fine particles that do not exhibit a eutectic.
　本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら新規な実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これら実施形態やその変形は、発明の範囲や要旨に含まれるとともに、特許請求の範囲に記載された発明とその均等の範囲に含まれる。 Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.
１　　　　　：レーザー装置
２　　　　　：レンズ
３　　　　　：容器
３ａ　　　　：開口部
４　　　　　：溶液
３１　　　　：蓋
１００　　　：製造装置
Ｓ１１０　　：溶液形成工程
Ｓ１２０　　：照射工程 1: Laser device 2: Lens 3: Container 3a: Opening 4: Solution 31: Lid 100: Manufacturing device S110: Solution forming process S120: Irradiation process

Claims (11)

  1. 　フェムト秒パルスレーザーを用いた微粒子の製造方法であって、
    　微粒子の前駆体と、前記微粒子の酸化を抑制する酸化抑制溶媒とを混合した溶液を、容器内に形成する溶液形成工程と、
    　前記フェムト秒パルスレーザーを集光し、前記溶液に対して照射する照射工程と、
    　を備えることを特徴とする微粒子の製造方法。     A method for producing fine particles using a femtosecond pulsed laser, the method comprising:
    a solution forming step of forming in a container a solution in which a precursor of fine particles and an oxidation-inhibiting solvent that suppresses oxidation of the fine particles are mixed;
    an irradiation step of condensing the femtosecond pulsed laser and irradiating the solution;
    A method for producing fine particles, comprising:
  2. 　前記前駆体は、金属塩を含み、
    　前記酸化抑制溶媒は、アルコールを含むこと
    　を特徴とする請求項１記載の微粒子の製造方法。     The precursor includes a metal salt,
    The method for producing fine particles according to claim 1, wherein the oxidation-inhibiting solvent contains alcohol.
  3. 　前記金属塩に含まれる金属イオンの酸化還元電位は、負を示すこと
    　を特徴とする請求項２記載の微粒子の製造方法。     3. The method for producing fine particles according to claim 2, wherein the metal ions contained in the metal salt have a negative redox potential.
  4. 　前記金属塩は、酸化還元電位が負を示す２種類以上の材料を含むこと
    　を特徴とする請求項２記載の微粒子の製造方法。     3. The method for producing fine particles according to claim 2, wherein the metal salt contains two or more types of materials having a negative redox potential.
  5. 　前記酸化抑制溶媒は、前記アルコールのみを含むこと
    　を特徴とする請求項２記載の微粒子の製造方法。     The method for producing fine particles according to claim 2, wherein the oxidation-inhibiting solvent contains only the alcohol.
  6. 　前記前駆体は、前記微粒子の中央径よりも大きい中央径を有する固体粒子を含むこと
    　を特徴とする請求項１記載の微粒子の製造方法。     The method for producing fine particles according to claim 1, wherein the precursor includes solid particles having a larger median diameter than the median diameter of the fine particles.
  7. 　前記前駆体は、有機金属錯体を含み、
    　前記酸化抑制溶媒は、フェニル基を有する材料を含むこと
    　を特徴とする請求項１記載の微粒子の製造方法。     The precursor includes an organometallic complex,
    The method for producing fine particles according to claim 1, wherein the oxidation-inhibiting solvent contains a material having a phenyl group.
  8. 　前記照射工程は、前記容器を介して、前記溶液に対して前記フェムト秒パルスレーザーを照射すること
    　を特徴とする請求項１～７の何れか１項記載の微粒子の製造方法。     8. The method for producing fine particles according to claim 1, wherein in the irradiation step, the solution is irradiated with the femtosecond pulse laser through the container.
  9. 　前記容器は、前記容器の開口部を覆う蓋を含むこと
    　を特徴とする請求項１～７の何れか１項記載の微粒子の製造方法。     The method for producing fine particles according to any one of claims 1 to 7, wherein the container includes a lid that covers an opening of the container.
  10. 　請求項１～４の何れか１項記載の微粒子の製造方法により生成された前記微粒子と、
    　前記微粒子が分散された溶媒と、
    　を備えること
    　を特徴とするコロイド溶液。     The fine particles produced by the method for producing fine particles according to any one of claims 1 to 4,
    a solvent in which the fine particles are dispersed;
    A colloidal solution comprising:
  11. 　前記溶媒は、アルデヒド基を有する化合物を含むこと
    　を特徴とする請求項１０記載のコロイド溶液。     The colloidal solution according to claim 10, wherein the solvent contains a compound having an aldehyde group.
PCT/JP2023/017011 2022-05-02 2023-05-01 Method for producing fine particles, and colloidal solution WO2023214558A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008006513A (en) * 2006-06-27 2008-01-17 Kyoto Univ Method for manufacturing nanosize wire and nanosize wire
JP2008031554A (en) * 2006-06-30 2008-02-14 Ne Chemcat Corp Process for producing metal nanoparticle and metal nanoparticle produced by the process

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008006513A (en) * 2006-06-27 2008-01-17 Kyoto Univ Method for manufacturing nanosize wire and nanosize wire
JP2008031554A (en) * 2006-06-30 2008-02-14 Ne Chemcat Corp Process for producing metal nanoparticle and metal nanoparticle produced by the process

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