JP2013230946A - Method of manufacturing silicon fine particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing silicon fine particles, capable of improving the yield of the silicon fine particles.SOLUTION: A method of manufacturing silicon fine particles includes process A for preparing powder that contains silicon particles, process B for cracking a mixed solution generated by adding the powder to an organic solvent, and process C for adding an etching solution to the cracked mixed solution to obtain silicon fine particles with smaller particle diameter than the silicon particle. The powder contains a plurality of silicon particles agglomerated.

Description

  The present invention relates to a method for producing silicon fine particles.

  Conventionally, as a simple method for producing silicon fine particles, a method for producing silicon fine particles from a composite powder composed of silicon particles covered with silicon oxide (SiOx, x = 1 or 2) is known (for example, Patent Documents). 1). The composite powder is obtained by firing a mixture containing a silicon source and a carbon source in an inert atmosphere and quenching a gas generated by the firing. The obtained composite powder was immersed in an etching solution containing hydrofluoric acid and an oxidizing agent to etch (dissolve) silicon oxide and silicon particles. As a result, silicon fine particles having a nanometer particle size were obtained from the composite powder. Note that silicon fine particles having a desired particle diameter can be obtained by adjusting the etching time and the etching concentration.

JP 2007-112656 A

  However, in many cases, the composite powder immersed in the etching solution contains a plurality of silicon particles in an aggregated state. However, in the manufacturing method according to the prior art, a plurality of silicon particles are included in an aggregated state. The composite powder was dissolved by an etching solution to obtain silicon fine particles having a desired particle size.

  That is, in the manufacturing method according to the prior art, by dissolving some of the plurality of silicon particles contained in the composite powder, silicon fine particles having a desired particle diameter can be obtained, but many agglomerated silicon particles are dissolved. Therefore, there was a problem that the yield of silicon fine particles was low.

  This invention is made | formed in view of the situation mentioned above, and aims at providing the manufacturing method of the silicon fine particle which can improve the yield of a silicon fine particle.

  In order to solve the above-described problems, the present invention has the following features.

  In the method for producing silicon fine particles according to the first feature of the present invention, a step A (step S1) of preparing a powder containing silicon particles, and a mixed solution generated by adding the powder to an organic solvent are crushed. Step B (Step S105) and Step C (Step S106) of adding an etching solution to the crushed mixed solution to obtain silicon fine particles having a particle diameter smaller than that of the silicon particles. The gist is that a plurality of silicon particles are aggregated and contained.

  According to the manufacturing method according to the feature of the present invention, since the process B includes crushing the mixed solution of the powder and the organic solvent that are contained in a state where a plurality of silicon particles are aggregated, the crushing process B is not included. Compared to the case, the powder can be dispersed. That is, according to this manufacturing method, it is possible to increase the quantity of powder after pulverization by pulverizing the powder. Further, in the step C of obtaining the silicon fine particles by adding the etching solution to the pulverized mixed solution, the number of silicon fine particles obtained depends on the number of powders contained in the mixed solution.

  That is, according to this manufacturing method, it is possible to increase the quantity of silicon fine particles obtained by increasing the quantity of powder in the step B of crushing. Thus, according to this manufacturing method, the yield of silicon fine particles can be improved.

  Another feature of the present invention relates to the above feature, and is summarized in that the organic solvent is an alcohol.

  Another feature of the present invention is related to the above feature, wherein the step A includes a step A1 of firing a mixture containing a silicon source and a carbon source in an inert atmosphere, and a gas generated by firing the mixture. And a step A2 of obtaining a composite powder covered with silicon oxide and a step A3 of obtaining the powder by immersing the composite powder in a solution dissolving the silicon oxide. .

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the silicon fine particle which can improve the yield of a silicon fine particle can be provided.

FIG. 1 is a schematic configuration diagram of a manufacturing apparatus 1 used for manufacturing silicon fine particles according to the present embodiment. FIG. 2 is a flowchart for explaining the method for producing silicon fine particles according to the present embodiment. FIG. 3 is a graph showing measurement results obtained by measuring the particle size distribution of the powder before pulverizing the powder and the particle size distribution of the powder after pulverizing the powder. FIG. 4A is an image obtained by photographing the powder before crushing using a transmission electron microscope. FIG. 4B is an image obtained by photographing the powder after crushing using a transmission electron microscope. FIG. 5A shows a silicon fine particle (G) that emits green light, a silicon fine particle (Y) that emits yellow light, and a silicon fine particle that emits red light (of the silicon fine particles manufactured by the manufacturing method according to the present embodiment). It is the graph which measured the wavelength and emitted light intensity for (R). FIG. 5B shows a silicon fine particle (G) that emits green light, a silicon fine particle (Y) that emits yellow light, and a silicon fine particle that emits red light (of the silicon fine particles manufactured by the manufacturing method according to this embodiment). R) is a photographed image of each. FIG. 6A is a conceptual diagram when terminating the surface of the silicon fine particles manufactured by the manufacturing method according to the prior art. FIG. 6B is a conceptual diagram when terminating the surface of the silicon fine particles manufactured by the manufacturing method according to the present embodiment. FIG. 7 is a graph showing measurement results obtained by measuring the wavelength and emission intensity of Example 1 and Comparative Example.

  One example of the method for producing silicon fine particles according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. It should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. It goes without saying that the drawings include parts having different dimensional relationships and ratios.

[First Embodiment]
The first embodiment of the present invention will be described below.

(Schematic configuration of manufacturing equipment)
First, a schematic configuration of a manufacturing apparatus 1 used for manufacturing silicon fine particles according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a manufacturing apparatus 1 used for manufacturing silicon fine particles according to the present embodiment. The production apparatus 1 is used for producing a composite powder containing silicon particles and silicon oxide particles.

  As shown in FIG. 1, the manufacturing apparatus 1 includes a heating container 2 that contains a mixture containing a silicon source and a carbon source in a container W to form a heating atmosphere, a stage 8 that holds the heating container 2, and a container W. A heating element 10a and a heating element 10b for heating the contained mixture, a heat insulating material 12 covering the heating container 2, the heating element 10a and the heating element 10b, and a blower for sucking the reaction gas from the heating container 2 through the suction pipe 21 23, a dust collector 22 for storing the composite powder, and a suction device 20 having a supply pipe 24 for supplying gas. The suction device 20 can suck SiO gas while maintaining a heated and inert atmosphere in the heating container 2. The inside of the suction device 20 is provided so that argon gas circulates. Moreover, the electromagnetic valve 25 which opens and closes automatically by setting pressure is provided.

(Method for producing silicon fine particles)
A method for producing silicon fine particles according to the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart for explaining the method for producing silicon fine particles according to the present embodiment. As shown in FIG. 2, steps S101 to S104 are preparation steps S1 for preparing powder containing silicon particles. That is, it is a step of preparing a powder containing a plurality of silicon particles in an aggregated state.

  As shown in FIG. 2, in step S101, a mixture composed of a silicon source and a carbon source is generated. As the silicon source, that is, the silicon-containing raw material, a liquid silicon source and a solid silicon source can be used in combination. However, at least one kind must be selected from a liquid silicon source.

  As the liquid silicon source, a polymer of alkoxysilane (mono-, di-, tri-, tetra-) and tetraalkoxysilane is used. Among the alkoxysilanes, tetraalkoxysilane is preferably used. Specific examples include methoxysilane, ethoxysilane, propoxysilane, butoxysilane and the like. From the viewpoint of handling, ethoxysilane is preferable. Examples of the tetraalkoxysilane polymer include a low molecular weight polymer (oligomer) having a degree of polymerization of about 2 to 15 and a silicate polymer having a high degree of polymerization and a liquid silicon source.

  Examples of the solid silicon source that can be used in combination with the liquid silicon source include silicon oxide. Examples of silicon oxide include silica sol (a colloidal ultrafine silica-containing liquid containing an OH group and an alkoxyl group), silicon dioxide (silica gel, fine silica, quartz powder) and the like in addition to SiO.

  Among these silicon sources, from the viewpoints of homogeneity and handling properties, tetraethoxysilane oligomers, mixtures of tetraethoxysilane oligomers and fine powder silica, and the like are preferable.

  In order to obtain high-purity silicon carbide powder, it is preferable to use a high-purity substance as the silicon source. Specifically, the initial impurity content is preferably 20 ppm or less, and more preferably 5 ppm or less.

  Examples of impurities include heavy metal elements such as Fe, Ni, Cu, Cr, V, and W, alkali metal elements such as Li, Na, and K, and alkaline earth such as Be, Mg, Ca, B, Al, and Ga. Or amphoteric metal elements.

  The carbon source, that is, the carbon-containing raw material is synthesized by using a catalyst that does not contain an impurity element, and can be any one or two or more kinds of organic materials that can be cured by being polymerized or crosslinked by heating and / or a catalyst or a crosslinking agent. Monomers, oligomers and polymers composed of compounds.

  Preferable specific examples of the carbon-containing raw material include curable resins such as phenol resins, furan resins, urea resins, epoxy resins, unsaturated polyester resins, polyimide resins, and polyurethane resins synthesized using a catalyst that does not contain an impurity element. Is mentioned. In particular, a resol type or novolac type phenol resin having a high residual carbon ratio and excellent workability is preferable.

  The resol type phenol resin useful in the present embodiment is monovalent or divalent such as phenol, cresol, xylenol, resorcin, bisphenol A in the presence of a catalyst (specifically, ammonia or organic amine) that does not contain an impurity element. It is produced by reacting a valent phenol with an aldehyde such as formaldehyde, acetaldehyde, or benzaldehyde.

  The organic amine used as the catalyst may be any of primary, secondary, and tertiary amines. As the organic amine, dimethylamine, trimethylamine, diethylamine, triethylamine, dimethylmonoethanolamine, monomethyldiethanolamine, N-methylaniline, pyridine, morpholine and the like can be used.

  As a method of synthesizing a resol type phenol resin by reacting phenols and aldehydes in the presence of ammonia or an organic amine, conventionally known methods can be adopted except that the catalyst used is different.

  That is, 1 to 3 moles of aldehydes and 0.02 to 0.2 moles of organic amine or ammonia are added to 1 mole of phenols and heated to 60 to 100 ° C.

  On the other hand, the novolak type phenolic resin useful in the present embodiment is a mixture of monovalent or divalent phenols and aldehydes similar to those described above, and acids containing no impurity elements (specifically, hydrochloric acid, sulfuric acid, p. -Toluenesulfonic acid or oxalic acid) can be used as a catalyst for the reaction.

  A conventionally well-known method can be employ | adopted also for manufacture of a novolak type phenol resin. That is, with respect to 1 mol of phenols, 0.5 to 0.9 mol of aldehydes and 0.02 to 0.2 mol of inorganic acid or organic acid not containing an impurity element are added and heated to 60 to 100 ° C. .

  In step S11, a catalyst or a crosslinking agent for polymerization or crosslinking is added to a raw material mixture obtained by mixing a silicon-containing raw material and a carbon-containing raw material, if necessary, and dissolved in a solvent. A mixture is formed by causing a polymerization or crosslinking reaction. The raw material mixture is heated at about 150 ° C. Thereby, the mixture is dried. The Si / C ratio is preferably 0.5 to 3.0.

  In step S102, a mixture containing a silicon source and a carbon source is fired under an inert atmosphere. Specifically, the mixture obtained in step S101 is accommodated in the container W. Using the heating element 10a and the heating element 10b, the mixture is heated and fired in an inert gas atmosphere to carbonize and silicify the mixture. As a result, a gas containing carbon and silicon is generated. Specifically, as shown in the following formula (1), silicon monoxide (SiO) is generated.

SiO2 + C → SiO + CO (1)
An inert gas atmosphere is a non-oxidizing atmosphere. Inert gases include, for example, vacuum, nitrogen, helium or argon.

  In step S103, the gas generated by firing the mixture is quenched to obtain a composite powder covered with silicon oxide. Specifically, the blower 23 is operated. Then, the generated gas is extracted from the inside of the heating container 2 through the suction pipe 21 by being put on an argon gas stream. Since the outside of the heat insulating material 12 is kept at room temperature, the generated gas is rapidly cooled to room temperature. A composite powder covered with silicon oxide is obtained from the product gas. Specifically, by cooling at a temperature of less than 1600 ° C., a composite powder containing silicon particles is obtained as shown by the following formula (2).

2SiO → Si + SiO2 (2)
However, since the reaction of the formula (2) does not proceed completely, the composite powder contains not only Si and SiO2, but also SiO. That is, the composite powder is composed of Si and SiOx (x = 1 or 2) excluding impurities. The composite powder contains at least a plurality of silicon particles Si in an aggregated state.

  Further, the obtained composite powder is collected in the dust collector 22. The argon stream is sent to the heating container 2 through the supply pipe 24.

  In step S104, the composite powder is immersed in a solution in which silicon oxide is dissolved to obtain a powder in which a plurality of silicon particles are aggregated and contained. Specifically, an acid that dissolves silicon oxide is added to the collected composite powder. Thus, by dissolving the silicon oxide covering the composite powder, a powder containing a plurality of silicon particles aggregated and contained can be obtained. In the present embodiment, in order to distinguish between the powder and the composite powder, the powder is appropriately described as an aggregated powder.

  Specifically, such an agglomerated powder can be obtained by filtering a solution obtained by adding an acid to a composite powder at 25 ° C. for 30 minutes using an ultrasonic cleaner and then filtering. The filtration method is not particularly limited, and the filtration may be performed under a normal pressure or a reduced pressure using a known filter medium.

  In addition, as an acid, hydrofluoric acid (HF) is mentioned, for example. Further, it is not always necessary to dissolve all the silicon oxide covering the silicon particles. That is, the aggregated powder may contain silicon oxide.

  In step S105, a mixed solution formed by adding aggregated powder (powder) containing a plurality of silicon particles aggregated to an organic solvent is crushed. Specifically, an organic solvent is added to the agglomerated powder obtained in step S104 to produce a slurry mixed solution. In addition, as an organic solvent, alcohol is preferable and methanol is more preferable. In this embodiment, methanol is used as the organic solvent. The organic solvent is not limited to methanol, and any solvent may be used as long as it does not react with silicon particles.

  Next, the mixed powder contained in the mixed solution is crushed by crushing the mixed solution using a wet shear crusher. That is, by crushing the agglomerated powder, the number of agglomerated powders is increased. At this time, the particle size of the powder can be about 8 μm to about 100 nm. The particle size of the pulverized powder is more preferably 100 nm or less.

  The wet shear crusher feeds the mixed solution to the nozzle part with a high-pressure plunger pump, and crushes the agglomerated powder contained in the mixed solution by high-speed shearing force generated when passing through the nozzle part. Can do. In the present embodiment, the pressure value at this time is 200 MPa. Any wet shearing crusher may be selected as long as it is a contamination-free material that does not contain other substances. The crushing method is not limited to the method using a wet shear crusher, and any method may be used.

  In step S106, an etching solution is added to the crushed mixed solution to obtain silicon fine particles having a particle diameter smaller than that of the silicon particles. Specifically, an etching solution containing hydrofluoric acid and an oxidizing agent is added to the mixed solution in the slurry state obtained in step S105. At this time, it is preferable to add the etching solution without drying the crushed mixed solution. This is to prevent the separated agglomerated powder from aggregating again due to drying.

  Moreover, as an oxidizing agent, nitric acid (HNO3) and hydrogen peroxide (H2O2) are mentioned, for example. In order to easily collect the silicon fine particles, a slightly polar solvent (for example, 2-propanol) may be mixed in the etching solution.

  Here, it is necessary to appropriately adjust the etching time according to the silicon fine particles having a particle diameter to be produced. Etching is allowed to proceed for a predetermined time, and when fine silicon particles having a desired particle diameter are obtained, the fine silicon particles are taken out from the etching solution. Specifically, silicon fine particles are obtained by filtering the etching solution. The filtration method is not particularly limited, and the filtration may be performed under a normal pressure or a reduced pressure using a known filter medium. Note that in the above-described etching, ultrasonic waves may be irradiated, or the temperature may be heated to a temperature higher than normal temperature.

  In step S107, the silicon fine particles are terminated. Specifically, the hydrogen atom added to the surface of the silicon fine particles obtained in step S106 is replaced with an organic molecule such as an unsaturated hydrocarbon group. The unsaturated hydrocarbon group should just have an unsaturated hydrocarbon group which has a hydrophilic group. For example, 1-decene, tetradecene, 1-octene, styrene and the like can be mentioned. Moreover, the group | base produced | generated from the isoprenoid compound which has a hydrophilic group may be sufficient. For example, monoterpenoids such as linalool are applicable. The unsaturated hydrocarbon group having a hydrophilic group may be a group generated from an allyl compound having a hydrophilic group. For example, allyl alcohol, eugenol, etc. are applicable.

  By performing the termination treatment on the surface of the silicon fine particles in this way, it is possible to suppress the surface of the silicon fine particles from being oxidized (deteriorated). In addition, you may perform the deoxygenation process by pressure reduction deaeration before performing a terminal process to a silicon microparticle. In this case, the oxidation of the silicon fine particles can be further suppressed. Further, after that, a solution containing silicon fine particles may be subjected to a separation treatment using a centrifugal separator to obtain silicon fine particles separated according to particle size.

(Action / Effect)
According to the method for producing silicon fine particles according to this embodiment, a step of preparing a powder containing silicon particles, a step of pulverizing a mixed solution generated by adding the powder to an organic solvent, and pulverized mixing Adding an etching solution to the solution to obtain silicon fine particles. Further, the powder contains a plurality of silicon particles aggregated.

  According to such a manufacturing method, the method includes the step of crushing the mixed solution of the aggregated powder and the organic solvent that are contained in a state where a plurality of silicon particles are aggregated. It becomes possible to disperse the powder. That is, it becomes possible to increase the number of powders of the aggregated powder.

  Here, FIG. 3 shows a graph showing measurement results obtained by measuring the particle size distribution before pulverizing the aggregated powder and the particle size distribution after pulverizing the aggregated powder. In the graph of FIG. 3, the horizontal axis represents the particle size, and the vertical axis represents the content ratio of the powder.

As shown in FIG. 3, it can be seen that there are many aggregated powders having a particle size of about 8 μm before crushing, but there are many aggregated powders having a particle size of about 100 nm after crushing. Furthermore, since the peak of the particle size distribution is sharp after pulverization, it can be seen that the agglomerated powder having a predetermined particle size has increased dramatically. 4A is an image obtained by photographing the aggregated powder before being crushed using a transmission electron microscope, and FIG. 4B is crushed using a transmission electron microscope. It is the image which image | photographed the subsequent agglomerated powder.

  Thus, according to this manufacturing method, it becomes possible to increase the number of powders after crushing by crushing the agglomerated powder. Further, since the number of silicon fine particles depends on the number of agglomerated powder to which an etching solution is added, the number of silicon fine particles can be increased. That is, according to the manufacturing method according to the present embodiment, the yield of silicon fine particles can be improved.

  In addition, according to the manufacturing method according to the present embodiment, as shown in FIG. 3, since the peak of the particle size distribution is sharp after pulverization, the agglomerated powder having a predetermined particle size is obtained. Since the body can be dramatically increased, it is possible to increase the yield of silicon fine particles having a uniform particle diameter.

  Furthermore, according to the manufacturing method according to the present embodiment, silicon fine particles that emit light of various colors can be efficiently obtained. For example, if silicon particles that emit green light are generated, the particle size of the silicon particles is 1.4 to 2.0 nm. If silicon particles that emit yellow light are generated, the particle size of the silicon particles is 2 If silicon fine particles emitting red light are generated at a thickness of 0.0 to 2.5 nm, it is preferable to generate silicon fine particles with a particle size of 2.5 to 3.5 nm.

  Here, in FIG. 5A, among the silicon fine particles manufactured by the manufacturing method according to the present embodiment, the silicon fine particles (G) emitting green light, the silicon fine particles (Y) emitting yellow light, and the red light emission. The graph which measured the wavelength and the emitted light intensity was shown for each of the silicon fine particles (R). FIG. 5B shows, among the silicon fine particles manufactured by the manufacturing method according to the present embodiment, the silicon fine particles (G) that emit green light, the silicon fine particles (Y) that emit yellow light, and the silicon fine particles that emit red light. Images taken with (R) are shown.

  As shown in FIGS. 5A to 5B, according to the manufacturing method according to the present embodiment, it becomes possible to increase the yield of silicon fine particles having a desired particle diameter, and thus any color is emitted. Even with silicon fine particles, the yield can be increased. That is, according to the manufacturing method according to this embodiment, in addition to the silicon fine particles (R), even if the silicon fine particles have a small particle diameter such as silicon fine particles (G) and silicon fine particles (Y), the yield can be increased. It becomes possible to increase.

  Further, FIG. 6A shows a conceptual diagram when the surface of the silicon fine particles manufactured by the manufacturing method according to the prior art is terminated. That is, FIG. 6A shows a conceptual diagram when the surface of the silicon fine particles obtained from the powder that is not crushed is terminated.

  As shown in FIG. 6 (a), the silicon fine particles produced by the production method according to the prior art are obtained from agglomerated powder that has not been crushed, so that a plurality of silicon fine particles are terminated in an aggregated state. . In such a case, the contact portion of the plurality of silicon fine particles becomes an unterminated portion. As a result, when a part of the plurality of silicon fine particles was separated after the termination, oxidation (deterioration) proceeded from the unterminated portion, and the light emission characteristics such as emission color and light emission intensity of the silicon fine particles were changed.

  On the other hand, FIG. 6B shows a conceptual diagram when the surface of the silicon fine particles manufactured by the manufacturing method according to the present embodiment is terminated. That is, FIG. 6A shows a conceptual diagram when the surface of the silicon fine particles obtained from the pulverized powder is terminated.

  As shown in FIG. 6B, since the silicon fine particles produced by the production method according to the present embodiment are obtained from the pulverized aggregated powder, each silicon fine particle may be terminated in a separated state. It becomes possible. That is, according to the manufacturing method according to the present embodiment, it is possible to more reliably terminate the surface of the silicon fine particles and suppress oxidation (deterioration), thereby achieving long-term stabilization of the light emission characteristics of the silicon fine particles. It becomes possible.

  Further, according to the manufacturing method according to the present embodiment, since methanol is used as the organic solvent added to the aggregated powder in the crushing step of Step S105, the aggregated powder can be obtained without causing unnecessary reaction to the silicon particles. It becomes possible to break up the body.

  In addition, according to the manufacturing method according to the present embodiment, in the melting step of step S104, the aggregated powder is obtained after dissolving the silicon oxide covering the composite powder, so that the silicon particles contained in the aggregated powder are contained. It becomes possible to increase the rate. Therefore, in the crushing step of step S105, by crushing the agglomerated powder, even if the agglomerated powder is dispersed, the content of silicon particles contained in each agglomerated powder can be increased. That is, according to the manufacturing method according to the present embodiment, the yield of silicon fine particles obtained by adding the etching solution can be further improved.

[Comparison evaluation]
Next, in order to further clarify the effects of the present invention, the yields of the silicon fine particles manufactured using the manufacturing method according to the example and the silicon fine particles manufactured using the manufacturing method according to the comparative example were compared. The present invention is not limited to these examples.

  A mixed solution consisting of 620 g of ethyl silicate as a silicon source, 288 g of phenol resin as a carbon source, and 92 g (35 wt%) of an aqueous maleic acid solution as a polymerization catalyst was heated at 150 ° C. to solidify. Next, the obtained mixture was carbonized at 900 ° C. for 1 hour under a nitrogen atmosphere. The resulting carbide was heated at 1600 ° C. under an argon atmosphere.

  The reaction gas generated during heating at 1600 ° C. was conveyed out of the heating container 2 using a suction device 20 and a carrier gas of argon gas, and then rapidly cooled to obtain a composite powder.

  0.5 g of the obtained composite powder was immersed in 30 ml of water. To this solution, 5 ml of 48% hydrofluoric acid (HF) was added. This solution was mixed and filtered through a membrane filter. The residue of the membrane filter (containing silicon particles) was dispersed in 10 ml of methanol, and this solution was crushed using a jet mill pulverizer.

Further, 10 ml of 48% hydrofluoric acid (HF) and 1 ml of 68% nitric acid (HNO ₃ ) were added to the solution (slurry) after pulverization. The surface of the silicon particles was etched for a predetermined time while stirring the acid solution, and the acid solution was filtered through a membrane filter in the same manner as described above to obtain a filter paper containing silicon fine particles. After the filter paper was dispersed in 1-decene at 90 ° C., the precipitate was removed using a centrifuge to obtain a solution containing silicon fine particles. This solution was measured as emission intensity as Example 1. In addition, Hitachi Ltd. spectrofluorimeter F-7000 was used for the measurement of emitted light intensity.

For comparison, a solution containing silicon fine particles obtained without crushing was used as a comparative example. Specifically, 0.5 g of the composite powder was added with 10 ml of 48% hydrofluoric acid (HF) and 1 ml of 68% nitric acid (HNO ₃ ). While stirring the acid solution, the surface of the silicon particles was etched for a predetermined time, and then the acid solution was filtered with a membrane filter to obtain a filter paper containing silicon fine particles. After the filter paper was dispersed in 1-decene at 90 ° C., the precipitate was removed using a centrifuge to obtain a solution containing silicon fine particles. Using this solution as a comparative example, the emission intensity of a comparative example having the same amount as in Example 1 was measured. The measurement results of Example 1 and the comparative example are shown in FIG.

  As shown in FIG. 7, as a result of measuring the emission intensity, it was confirmed that Example 1 was significantly higher than the comparative example. Since the emission intensity depends on the content (number of particles) of silicon fine particles in the solution, it was proved that Example 1 had a larger content (number of particles) of silicon fine particles. That is, it has been proved that the production method according to the present invention improves the yield of silicon fine particles.

[Other embodiments]
Although the present invention has been described according to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the method for producing silicon fine particles according to the present embodiment, the silicon particles are prepared in the preparation step S1, but the present invention is not necessarily limited thereto. You may prepare by purchasing a commercially available silicon particle.

  Thus, the present invention includes various embodiments not described herein. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

DESCRIPTION OF SYMBOLS 1 ... Heating device, 2 ... Heating container, 8 ... Stage, 10a, 10b ... Heating element, 12 ... Heat insulating material, 20 ... Suction device, 22 ... Dust collector, 23 ... Blower, 24 ... Supply pipe, 25 ... Solenoid valve, W ... containers

Claims (3)

Preparing a powder containing silicon particles, step A;
Step B for crushing a mixed solution produced by adding the powder to an organic solvent;
Adding an etching solution to the crushed mixed solution to obtain silicon fine particles having a particle diameter smaller than that of the silicon particles, and
The method for producing silicon fine particles, wherein the powder contains a plurality of silicon particles aggregated. 2. The method for producing silicon fine particles according to claim 1, wherein the organic solvent is an alcohol. Step A includes
A step A1 of firing a mixture containing a silicon source and a carbon source under an inert atmosphere;
Step A2 for rapidly cooling the gas generated by firing the mixture to obtain a composite powder covered with silicon oxide;
3. The method for producing silicon fine particles according to claim 1, comprising a step A3 of immersing a composite powder in a solution dissolving silicon oxide to obtain the powder.