Method for manufacturing diamond particles
A solution-based method for synthesizing diamond particles using organic solvents and salts at controlled conditions addresses the lack of efficient solution-based diamond synthesis, enabling applications in advanced technologies like quantum dots and nanoscale sensors.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- NAT INST FOR MATERIALS SCI
- Filing Date
- 2021-12-21
- Publication Date
- 2026-07-22
AI Technical Summary
Existing methods for synthesizing diamond do not involve a solution-based process, and there is a need for a technique to produce diamond nanoparticles efficiently without specialized equipment.
A method involving mixing a carbon-containing organic solvent with a salt to form a mixture, followed by aging the mixture at specific temperatures and pressures, results in the formation of diamond particles with cubic and/or hexagonal crystal structures.
This method allows for the synthesis of clean-surfaced, impurity-free diamond particles suitable for applications in fluorescent semiconductor quantum dots, nanoscale magnetic sensors, and in vivo tracking, without requiring expensive equipment or complex techniques.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing diamond grains. child
Background Art
[0002] Diamond is known to have many unique properties such as high hardness, high thermal conductivity, high electrical resistivity, excellent chemical resistance, low thermal expansion coefficient, low friction coefficient, wide light transmission wavelength band, and biosynthesis, and is expected to have a wide range of applications in the electronics field.
[0003] As methods for synthesizing such diamond, high-pressure synthesis (see, for example, Non-Patent Document 1), chemical vapor deposition method (see, for example, Non-Patent Document 2), and explosive method (see, for example, Non-Patent Document 3) are known. None of these techniques is a technique for synthesizing diamond from a solution.
[0004] On the other hand, a nanoparticle synthesis method using a solvothermal method has been developed (see, for example, Patent Document 1). According to Patent Document 1, an organic solvent is allowed to coexist in a reaction field for forming nanoparticles of nanometer size from a liquid mixture system containing a nanoparticle precursor and a surfactant, and the nanoparticles of nanometer size are formed in the presence of the organic solvent, and it is reported that diamond nanoparticles can be synthesized.
[0005] However, in Patent Document 1, a specific method for synthesizing diamond nanoparticles is not disclosed, and further development of a technique for synthesizing diamond from a solution is desired.
Prior Art Documents
Patent Documents
[0006]
Patent Document 1
Non-Patent Documents
[0007] [Non-Patent Document 1] FPBUNDY et al., Nature, volume 176, 51-55, 1955. [Non-Patent Document 2] John C. Angus et al., Journal of Applied Physics, 39, 2915, 1968 [Non-Patent Document 3] Paul S. Decarli et al., Science, Vol. 133, Issue 3467, 1821-1822, 1961. [Overview of the project] [Problems that the invention aims to solve]
[0008] From the above, the object of the present invention is to provide a method for synthesizing diamond from a solution. Law It is about providing. [Means for solving the problem]
[0009] The method for synthesizing diamond particles according to the present invention comprises mixing a solvent containing a carbon-containing organic solvent with a salt to obtain a mixture, and aging the mixture, thereby solving the above problem. The aforementioned organic solvents include alcohol-based solvents, ketone-based solvents, ester-based solvents, amide-based solvents, hydrocarbon-based solvents, aromatic-based solvents, cellosolve-based solvents, and , At least one solvent may be selected from the group consisting of logen-based solvents. The alcohol-based solvent may be selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, and allyl alcohol, with at least one selected from this group. The ketone solvent may be selected from the group consisting of acetone, methyl ethyl ketone, acetylacetone, isopropyl methyl ketone, isobutyl methyl ketone, 2-pentanone, 3-pentanone, cyclohexanone, and diketones, with at least one selected from this group. The ester solvent may be selected from the group consisting of ethyl acetate, propylene glycol monomethyl ether acetate, and 2-ethoxyethyl acetate. The amide solvent may be selected from the group consisting of N-methylpyrrolidone (NMP), N-ethyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N,N-dimethylformamide (DMF), and N,N-dimethylacetamide. The hydrocarbon solvent may be selected from the group consisting of n-hexane, n-heptane, n-octane, n-decane, n-dodecane, 2,3-dimethylhexane, 2-methylheptane, 2-methylhexane, 3-methylhexane, and cyclohexane. The aromatic solvent may be selected from the group consisting of benzene, toluene, xylene, trimethylbenzene, ethylbenzene, methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene, with at least one selected from this group. The cellosolve solvent may be selected from the group consisting of methyl cellosolve, ethyl cellosolve, butyl cellosolve, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, and triethylene glycol monomethyl ether. The halogenated solvent may be selected from the group consisting of dichloromethane, trichloromethane, carbon tetrachloride, and chloroform, with at least one selected from this group. The salt may be selected from the group consisting of metal halides, metal oxyhalides, metal nitrates, metal phosphates, and metal sulfates, with at least one selected from this group. The metal of the salt may be selected from the group consisting of Group 1 elements, Group 2 elements, Group 13 elements, and transition metal elements. The concentration of the salt in the mixture may be in the range of 0.001 g / L or more and 1000 g / L or less. The concentration of the salt in the mixture may be in the range of 0.3 g / L or more and 5 g / L or less. The aging process may involve holding the mixture in a temperature range of 0°C to 400°C for a period of 0.1 hours to 1000 hours. The aforementioned aging process involves aging at a temperature range of 10°C to 250°C for 20 hours. Time period The mixture may be held for a period of up to 200 hours. The aging process may be carried out by holding the mixture under atmospheric pressure or under the saturated vapor pressure of the solvent. The diamond particles according to the present invention have a cubic and / or hexagonal crystal structure and a particle size in the range of 0.5 nm to 1 mm, thereby solving the above problem. The particle size may be in the range of 1 nm to 100 nm. [Effects of the Invention]
[0010] The present invention provides a method for synthesizing diamond particles, which involves mixing a solvent containing a carbon-containing organic solvent with a salt to obtain a mixture, and then aging the mixture. Since diamond particles can be obtained simply by mixing and aging, it eliminates the need for special techniques or expensive equipment, making it advantageous for practical application. The diamond particles obtained in this way have a clean surface, are free of impurities, and can be applied to fluorescent semiconductor quantum dots, nanoscale magnetic sensors, in vivo tracking, drug delivery, and the like. [Brief explanation of the drawing]
[0011] [Figure 1] Flowchart showing the process for manufacturing diamond particles of the present invention [Figure 2] Figure 2 shows the procedures for Examples 1 to 10. [Figure 3]Figure showing the TEM image of diamond particles according to Example 1 [Figure 4] Figure showing the TEM image of diamond particles according to Example 2 [Figure 5] Figure showing the HR-TEM images observed from various crystal orientations of diamond particles according to Example 1 [Figure 6] Figure showing the HR-TEM images observed from various crystal orientations of diamond particles according to Example 2 [Figure 7] Figure showing the HR-TEM image of another diamond particle according to Example 2 [Figure 8] Figure showing the HR-TEM image of another diamond particle of Example 2
Embodiments for Carrying Out the Invention
[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same elements are denoted by the same numbers, and the description thereof will be omitted.
[0013] The diamond particles of the present invention and a method for producing the same will be described. The diamond particles of the present invention are produced by a method using a solution described later, have a cubic and / or hexagonal crystal structure, and have a particle size in the range of 0.5 nm or more and 1 mm or less. Since the diamond particles of the present invention have a clean surface and impurity-free characteristics, they can be applied to fluorescent semiconductor quantum dots, nanoscale magnetic sensors, in vivo tracking, drug delivery, etc.
[0014] The cubic diamond particles belong to the Fd3-m (in this specification, “-” represents the overbar of 3) space group (No. 227 in the International Tables for Crystallography). The hexagonal diamond particles belong to the P63 / mmc space group (No. 194 in the International Tables for Crystallography). The crystal structure can be easily analyzed by measuring an electron diffraction or a fast Fourier transform (FFT) pattern.
[0015] Each diamond particle is a single crystal particle, preferably having a particle size in the range of 1 nm to 100 nm. Within this range, it can be applied to the above-mentioned uses. Preferably, the diamond particles have a particle size in the range of 1 nm to 60 nm.
[0016] The particle size of the diamond particles is determined by measuring the particle size of 100 randomly selected particles in an image observed using a transmission electron microscope (TEM), and then using the average particle size.
[0017] The diamond particles of the present invention may have defects within a single particle. Such defects may be twinning and / or stacking faults. Even with defects, the clean surface and impurity-free properties can be maintained.
[0018] Figure 1 is a flowchart showing the process for manufacturing diamond particles according to the present invention.
[0019] Step S110: Mix a solvent containing a carbon-containing organic solvent with a salt to obtain a mixture. Step S120: The mixture obtained in Step S110 is aged. The inventors of this invention have discovered that the above-mentioned diamond particles can be synthesized simply by obtaining a raw material mixture and aging it. The method of the present invention is advantageous because it does not require special techniques or expensive equipment. Each step will be described in detail.
[0020] In step S110, the organic solvent containing carbon is not particularly limited as long as it contains carbon, but preferably at least one is selected from the group consisting of alcoholic solvents, ketoneic solvents, esteric solvents, amide solvents, hydrocarbon solvents, aromatic solvents, cellosolve solvents, and halogenated solvents. These are used to generate diamond particles by aging in step S120, which will be described later.
[0021] The alcoholic solvent is preferably selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, and allyl alcohol, with at least one selected from this group. These alcoholic solvents are readily available.
[0022] The ketone solvent is preferably selected from the group consisting of acetone, acetylacetone, methyl ethyl ketone, isopropyl methyl ketone, isobutyl methyl ketone, 2-pentanone, 3-pentanone, cyclohexanone, and diketones. These ketone solvents are preferred because they are readily available.
[0023] The ester solvent is preferably selected from the group consisting of ethyl acetate, propylene glycol monomethyl ether acetate, and 2-ethoxyethyl acetate. These ester solvents are preferred because they are readily available.
[0024] The amide solvent is preferably selected from the group consisting of N-methylpyrrolidone (NMP), N-ethyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N,N-dimethylformamide (DMF), and N,N-dimethylacetamide. These amide solvents are preferred because they are common solvents.
[0025] The hydrocarbon solvent is preferably selected from the group consisting of n-hexane, n-heptane, n-octane, n-decane, n-dodecane, 2,3-dimethylhexane, 2-methylheptane, 2-methylhexane, 3-methylhexane, and cyclohexane. These hydrocarbon solvents are preferred because they contain a methyl group (-CH3).
[0026] The aromatic solvent is preferably selected from the group consisting of benzene, toluene, xylene, trimethylbenzene, ethylbenzene, methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene, with at least one selected from this group. These aromatic solvents are preferred because they are readily available.
[0027] The cellosolve solvent is preferably selected from the group consisting of methyl cellosolve, ethyl cellosolve, butyl cellosolve, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, and triethylene glycol monomethyl ether. These cellosolve solvents are preferred because they are readily available.
[0028] The halogenated solvent is preferably selected from the group consisting of dichloromethane, trichloromethane, carbon tetrachloride, and chloroform. These cellosolve solvents are preferred because they are readily available.
[0029] Among the organic solvents mentioned above, those having alkyl groups with sp3 hybrid orbitals, such as a methyl group (-CH3), are preferred. The salt described later replaces hydrogen (H) atoms with carbon (C) atoms, forming a diamond nucleus and promoting the generation of diamond particles.
[0030] The above-mentioned organic solvents may be combined as the carbon-containing organic solvent. Furthermore, the solvent may be a carbon-containing organic solvent alone, or it may also contain water. The presence of water is preferable because it facilitates the dissolution of the salt. When water is present, the volume ratio of the organic solvent to the total volume of the solvent may be 0.1 or more and less than 1. Preferably, it is 0.5 or more and 0.9 or less.
[0031] In step S110, the salt functions as a catalyst. The salt is an inorganic salt, preferably at least one selected from the group consisting of metal halides, metal oxyhalides, metal nitrates, metal phosphates, and metal sulfates. These function as catalysts in step S120, described later, to generate diamond particles from the solvent. Among these, halides are preferred because they can easily abstract other atoms that bond with carbon atoms in the organic solvent.
[0032] Metals are selected from the group consisting of Group 1 elements, Group 2 elements, Group 13 elements, and transition metal elements. Examples of Group 1 elements include lithium (Li), sodium (Na), and potassium (K). Examples of Group 2 elements include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Examples of Group 13 elements include aluminum (Al), gallium (Ga), and indium (In). Transition metal elements include lanthanides, such as scandium (Sc), titanium (Ti), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), niobium (Nb), lanthanum (La), cerium (Ce), and neodymium (Nd).
[0033] In step S110, the concentration of salt in the mixture may preferably be in the range of 0.001 g / L to 1000 g / L. Diamond particles can be generated within this range. The concentration of salt in the mixture preferably satisfies the range of 0.1 g / L to 10 g / L. This improves the yield. The concentration of salt in the mixture more preferably satisfies the range of 0.3 g / L to 5 g / L. This further improves the yield. The concentration of salt in the mixture still more preferably satisfies the range of 0.5 g / L to 1.5 g / L.
[0034] In step S110, it is preferable to use an ultrasonic homogenizer, a high-pressure homogenizer, etc., to ultrasonically disperse the mixed liquid.
[0035] In step S120, aging simply involves holding the mixture, but preferably, the mixture is held for a period of 0.1 hours to 1000 hours in a temperature range of 0°C to 400°C. Within this range, diamond particles can be formed. Preferably, aging involves holding the mixture for a period of 20 hours to 200 hours in a temperature range of 10°C to 250°C.
[0036] In step S120, aging may be carried out under atmospheric pressure or under the saturated vapor pressure of the selected solvent. In particular, aging under saturated vapor pressure is preferable because it promotes the formation of diamond particles, allowing the holding time to be shortened to a range of 10 to 30 hours. Following step S120, a process of removing the solvent, recovering the product, and washing may be carried out. This removes the salts.
[0037] The inventors of this application have not yet elucidated the mechanism by which diamond particles are generated using a carbon-containing organic solvent and an inorganic salt, but they believe the following: When carbon atoms in the organic solvent have sp3 hybrid orbitals, or readily form sp3 hybrid orbitals, the catalyst salt abstracts atoms other than carbon that are bonded to the carbon atoms, and a CC bond is formed. For example, when the organic solvent has CH3 groups and a chloride is used as the salt, the CH3 groups are arranged in a tetrahedral configuration. - We consider that when the H is replaced by Cl, it becomes CCl4, and when the Cl is replaced by C, it becomes a diamond structure with a CC bond.
[0038] The diamond particles of this invention, utilizing the properties of diamond, can be applied to phosphorescent semiconductor quantum dots and nanoscale magnetic sensors. Furthermore, if used for in vivo tracking, it will enable the tracking of stem cell implantation and regenerative capabilities.
[0039] The present invention will now be described in detail using specific examples, but please note that the present invention is not limited to these examples. [Examples]
[0040] [Examples 1-10] In Examples 1 to 10, diamond particles were synthesized using various carbon-containing solvents and salts shown in Table 1. Figure 2 shows the procedures for Examples 1 to 10.
[0041] In detail, the salts shown in Table 1 were added to a carbon-containing organic solvent (50 mL) shown in Table 1 to the predetermined concentration and mixed to obtain a mixture (step S110 in Figure 1). The mixture was aged under the conditions shown in Table 1 (step S120 in Figure 1).
[0042] [Table 1]
[0043] The generated samples were washed multiple times with ethanol and then evaluated using a transmission electron microscope (TEM, JEOL Ltd., JEM-2100F). The results are shown in Figures 3 to 8 and Table 2.
[0044] Figure 3 shows a TEM image of diamond particles obtained in Example 1. Figure 4 shows a TEM image of diamond particles obtained in Example 2.
[0045] As shown in Figures 3 and 4, particles were generated that are shown in black for contrast. According to Figure 3, particles with a minimum particle size of 1 nm to a maximum particle size of 60 nm were observed, and according to Figure 4, particles with a particle size of 1 nm to 30 nm were observed. When the average particle size was measured using ImageJ (ver. 1.51n; open-source, public domain image processing software), the average particle size of the particles in Example 1 was 8 nm, and the average particle size of the particles in Example 2 was 12 nm. Although not shown, the particles from Examples 3 to 10 exhibited similar characteristics.
[0046] Figure 4 shows the selected-field electron diffraction (SAED) pattern of the particle, which exhibited clear Bragg reflection. Indexing with Miller indices revealed reflections at {111}, {220}, {311}, {400}, and {331}, which are attributed to the cubic diamond structure, as well as a reflection at {200}. This indicates that the obtained particle is a diamond particle with a cubic crystal structure. The {200} reflection is presumed to be an extinction reflection resulting from the cubic diamond structure, which is an Fd3-m space group, appearing due to the multiple scattering effect. The diamond particles in Examples 1, 3 to 10 were similarly confirmed to have a cubic crystal structure.
[0047] Figure 5 shows HR-TEM images of diamond particles observed from various crystal orientations according to Example 1. Figure 6 shows HR-TEM images of diamond particles observed from various crystal orientations according to Example 2.
[0048] Figures 5 and 6A-D show HR-TEM images and FFT diffraction patterns of diamond particles along
[0100] ,
[0110] ,
[0111] , and
[0112] , respectively. Figures 5 and 6 show that the diamond particles are single crystals. Although not shown, the diamond particles in Examples 3-10 were also single crystals.
[0049] Figure 7 shows an HR-TEM image of another diamond particle from Example 2.
[0050] Figures 7A and 7B show the HR-TEM images and FFT diffraction patterns of diamond particles along
[0100] and
[0001] , respectively. Figure 7 shows that hexagonal diamond particles are observed, indicating that they are single-crystal particles with a hexagonal crystal structure. Although not shown, in Examples 1, 3 to 10, some diamond particles were also found to have a similar hexagonal crystal structure.
[0051] Figure 8 shows an HR-TEM image of another diamond particle from Example 2.
[0052] As shown in Figure 8, diamond particles with twinning and stacking faults were observed. Although not shown, crystallographic defects were also observed in the diamond particles of Example 1 and Examples 3 to 10.
[0053] [Table 2] [Industrial applicability]
[0054] According to the present invention, diamond particles can be synthesized from a solvent. The diamond particles obtained in this way have a clean surface and are free of impurities, and can be applied to fluorescent semiconductor quantum dots, nanoscale magnetic sensors, in vivo tracking, drug delivery, and the like.
Claims
1. A mixture is obtained by mixing a solvent containing a carbon-containing organic solvent with a salt. Aging the aforementioned mixture It includes, The aforementioned salt is a metal halide, The aging process is a method for synthesizing diamond particles, in which the mixture is held in a temperature range of 10°C to 250°C for a period of 20 to 200 hours.
2. The method according to claim 1, wherein the organic solvent is selected from the group consisting of alcohol-based solvents, ketone-based solvents, ester-based solvents, amide-based solvents, hydrocarbon-based solvents, aromatic solvents, cellosolve-based solvents, and halogen-based solvents, at least one of these.
3. The method according to claim 2, wherein the alcohol-based solvent is selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, and allyl alcohol, at least one of these.
4. The method according to claim 2, wherein the ketone solvent is selected from the group consisting of acetone, methyl ethyl ketone, acetylacetone, isopropyl methyl ketone, isobutyl methyl ketone, 2-pentanone, 3-pentanone, cyclohexanone, and diketone.
5. The method according to claim 2, wherein the ester solvent is selected from the group consisting of ethyl acetate, propylene glycol monomethyl ether acetate, and 2-ethoxyethyl acetate.
6. The method according to claim 2, wherein the amide solvent is selected from the group consisting of N-methylpyrrolidone (NMP), N-ethyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N,N-dimethylformamide (DMF), and N,N-dimethylacetamide.
7. The method according to claim 2, wherein the hydrocarbon solvent is selected from the group consisting of n-hexane, n-heptane, n-octane, n-decane, n-dodecane, 2,3-dimethylhexane, 2-methylheptane, 2-methylhexane, 3-methylhexane, and cyclohexane, to the extent that the hydrocarbon solvent is selected from the group consisting of n-hexane, n-heptane, n-octane, n-decane, n-dodecane, 2,3-dimethylhexane, 2-methylheptane, 2-methylhexane, 3-methylhexane, and cyclohexane.
8. The method according to claim 2, wherein the aromatic solvent is selected from the group consisting of benzene, toluene, xylene, trimethylbenzene, ethylbenzene, methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene.
9. The method according to claim 2, wherein the cellosolve solvent is selected from the group consisting of methyl cellosolve, ethyl cellosolve, butyl cellosolve, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, and triethylene glycol monomethyl ether.
10. The method according to claim 2, wherein the halogenated solvent is selected from the group consisting of dichloromethane, trichloromethane, carbon tetrachloride, and chloroform, to the extent that the halogenated solvent is selected from the group consisting of dichloromethane, trichloromethane, carbon tetrachloride, and chloroform.
11. The method according to claim 1, wherein the metal of the salt is selected from the group consisting of Group 1 elements, Group 2 elements, Group 13 elements, and transition metal elements.
12. The method according to any one of claims 1 to 11, wherein the concentration of the salt in the mixed solution is in the range of 0.001 g / L or more and 1000 g / L or less.
13. The method according to claim 12, wherein the concentration of the salt in the mixed solution is in the range of 0.3 g / L or more and 5 g / L or less.
14. The aging is performed by holding the mixture under atmospheric pressure or under the saturated vapor pressure of the solvent, according to any one of claims 1 to 13.