Diamond particle, and method of producing the same
Patent Information
- Application Number
- JP2021206647
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2021-12-21
- Publication Date
- 2024-12-11
- Estimated Expiration
- 2041-12-21
AI Technical Summary
Existing methods for synthesizing diamond do not include techniques for producing diamond nanoparticles from a solution, and there is a need for a specific technique to achieve this.
A method involving mixing a carbon-containing organic solvent with a salt to form a mixture, followed by aging, which results in the formation of diamond particles with a cubic and/or hexagonal crystal structure, without requiring special techniques or expensive equipment.
The method allows for the production of clean-surfaced, impurity-free diamond particles with sizes ranging from 0.5 nm to 1 mm, suitable for applications in fluorescent semiconductor quantum dots, nanoscale magnetic sensors, and in vivo tracking.
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Abstract
Description
[Technical Field]
[0001] The present invention relates to diamond particles and a method for producing the same. [Background technology]
[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 coefficient of friction, wide optical transmission wavelength range, and biological synthesis, and is expected to have a wide range of applications in the electronics field.
[0003] Known methods for synthesizing such diamonds include high-pressure synthesis (see, for example, Non-Patent Document 1), chemical vapor deposition (see, for example, Non-Patent Document 2), and explosive detonation (see, for example, Non-Patent Document 3). None of these techniques synthesize diamonds from a solution.
[0004] Meanwhile, a method for synthesizing nanoparticles using a solvothermal method has been developed (see, for example, Patent Document 1). Patent Document 1 reports that diamond nanoparticles can be synthesized by making an organic solvent coexist in a reaction field where nanometer-sized particles are formed from a liquid mixture containing a nanoparticle precursor and a surfactant, and by forming the nanometer-sized particles in the presence of the organic solvent.
[0005] However, Patent Document 1 does not disclose a specific method for synthesizing diamond nanoparticles, and there is a need for the continued development of a technology for synthesizing diamond from a solution. [Prior art documents] [Patent documents]
[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-233845 [Non-patent literature]
[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 Summary of the Invention [Problem to be solved by the invention]
[0008] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for synthesizing diamond from a solution, and diamond particles. [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 mixed liquid, and aging the mixed liquid, thereby solving the above-mentioned problem. The organic solvent may be at least one 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. The alcohol solvent may be at least one 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. The ketone solvent may be at least one selected from the group consisting of acetone, methyl ethyl ketone, acetylacetone, isopropyl methyl ketone, isobutyl methyl ketone, 2-pentanone, 3-pentanone, cyclohexanone, and diketones. The ester solvent may be at least one selected from the group consisting of ethyl acetate, propylene glycol monomethyl ether acetate, and 2-ethoxyethyl acetate. The amide solvent may be at least one 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 at least one 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 at least one selected from the group consisting of benzene, toluene, xylene, trimethylbenzene, ethylbenzene, methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene. The cellosolve-based solvent may be at least one 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 halogen-based solvent may be at least one selected from the group consisting of dichloromethane, trichloromethane, carbon tetrachloride, and chloroform. The salt may be at least one selected from the group consisting of metal halides, metal oxyhalides, metal nitrates, metal phosphates, and metal sulfates. 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 mixed solution may be in the range of 0.001 g / L to 1000 g / L. The concentration of the salt in the mixed solution may be in the range of 0.3 g / L or more and 5 g / L or less. The aging may involve holding the mixed solution at a temperature in the range of 0° C. to 400° C. for 0.1 hours to 1000 hours. The aging may involve holding the mixed solution at a temperature in the range of 10° C. to 250° C. for 20 hours to 200 hours. The aging may be performed by holding the mixed solution 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-mentioned problems. The particle size may be in the range of 1 nm to 100 nm. [Effects of the Invention]
[0010] The method for synthesizing diamond particles of the present invention involves mixing a solvent containing a carbon-containing organic solvent with a salt to obtain a mixed solution, and then aging the mixed solution. Since diamond particles can be obtained simply by mixing and aging, no special techniques or expensive equipment are required, making it advantageous for practical use. The diamond particles obtained in this way have clean surfaces and are free of impurities, and can be used in fluorescent semiconductor quantum dots, nanoscale magnetic sensors, in vivo tracking, drug delivery, and other applications. [Brief explanation of the drawings]
[0011] [Figure 1] Flowchart showing the steps for producing diamond particles of the present invention [Figure 2] FIG. 2 is a diagram showing the procedures of Examples 1 to 10. [Figure 3] TEM image of diamond particles from Example 1 [Figure 4] TEM image of diamond particles from Example 2 [Figure 5] HR-TEM images of diamond particles from Example 1 observed from various crystal orientations. [Figure 6]HR-TEM images of diamond particles from Example 2, taken from various crystal orientations. [Figure 7] Figure 1 shows an HR-TEM image of another diamond particle from Example 2. [Figure 8] HR-TEM image of another diamond particle from Example 2. DETAILED DESCRIPTION OF THE INVENTION
[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that like elements are designated by like numbers and their description will be omitted.
[0013] The diamond particles of the present invention and the method for producing the same will now be described. The diamond particles of the present invention are produced by a solution-based method described below, have a cubic and / or hexagonal crystal structure, and have a particle size ranging from 0.5 nm to 1 mm. Because the diamond particles of the present invention have clean surfaces and are free of impurities, they can be used in applications such as fluorescent semiconductor quantum dots, nanoscale magnetic sensors, in vivo tracking, and drug delivery.
[0014] Cubic diamond particles belong to the Fd3-m (herein "-" represents a 3 overbar) space group (number 227 in the International Tables for Crystallography). Hexagonal diamond particles belong to the P63 / mmc space group (number 194 in the International Tables for Crystallography). Crystal structures are easily analyzed by electron diffraction or by measuring fast Fourier transform (FFT) patterns.
[0015] The diamond particles are each single crystal particles, and preferably have a particle size in the range of 1 nm to 100 nm. This range makes them suitable for the above-mentioned applications. More 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 sizes of 100 randomly selected particles in an image observed with a transmission electron microscope (TEM), and taking the average particle size.
[0017] The diamond particles of the present invention may have defects within a particle. Such defects may be twins and / or stacking faults. Even with the presence of defects, the diamond particles can maintain their clean surface and impurity-free properties.
[0018] FIG. 1 is a flow chart showing the steps for producing diamond particles of the present invention.
[0019] Step S110: A solvent containing a carbon-containing organic solvent is mixed with a salt to obtain a mixed solution. Step S120: The mixed liquid obtained in step S110 is aged. The inventors of the present invention have found that the above-mentioned diamond particles can be synthesized simply by obtaining a mixture of raw materials 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 carbon-containing organic solvent is not particularly limited as long as it contains carbon, but is preferably at least one 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. These solvents are aged to produce diamond particles in step S120, which will be described later.
[0021] The alcoholic solvent is preferably at least one 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, and these alcoholic solvents are readily available.
[0022] The ketone solvent is preferably at least one selected from the group consisting of acetone, acetylacetone, methyl ethyl ketone, isopropyl methyl ketone, isobutyl methyl ketone, 2-pentanone, 3-pentanone, cyclohexanone, and diketones, and these ketone solvents are preferred because they are easily available.
[0023] The ester solvent is preferably at least one selected from the group consisting of ethyl acetate, propylene glycol monomethyl ether acetate, and 2-ethoxyethyl acetate, which are preferred because they are readily available.
[0024] The amide solvent is preferably at least one 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, which are common solvents and therefore preferred.
[0025] The hydrocarbon solvent is preferably at least one 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, which contain a methyl group (—CH3).
[0026] The aromatic solvent is preferably at least one selected from the group consisting of benzene, toluene, xylene, trimethylbenzene, ethylbenzene, methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene, and these aromatic solvents are preferred because they are easily available.
[0027] The cellosolve solvent is preferably at least one 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, and these cellosolve solvents are preferred because they are easily available.
[0028] The halogen-based solvent is preferably at least one selected from the group consisting of dichloromethane, trichloromethane, carbon tetrachloride, and chloroform. These cellosolve-based solvents are preferred because they are readily available.
[0029] Among the above-mentioned organic solvents, those having an alkyl group with an sp3 hybrid orbital, such as a methyl group (-CH3), are preferred. The salts described below replace hydrogen (H) atoms with carbon (C) atoms, forming diamond nuclei and promoting the production of diamond particles.
[0030] The carbon-containing organic solvent may be a combination of the above organic solvents. Furthermore, the solvent may be a carbon-containing organic solvent alone, or may further contain water. If water is contained, it is preferable because the salt is easily dissolved. When water is contained, 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, a salt functions as a catalyst. The salt is an inorganic salt, and is preferably at least one selected from the group consisting of metal halides, metal oxyhalides, metal nitrates, metal phosphates, and metal sulfates. These salts function as catalysts in step S120, which will be described later, to generate diamond particles from the solvent. Among these, halides are preferred because they can easily extract other atoms bonded to carbon atoms in the organic solvent.
[0032] The metal is selected from the group consisting of Group 1 elements, Group 2 elements, Group 13 elements, and transition metal elements. Exemplary Group 1 elements include lithium (Li), sodium (Na), and potassium (K). Exemplary Group 2 elements include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Exemplary Group 13 elements include aluminum (Al), gallium (Ga), and indium (In). Transition metal elements also 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 salt concentration in the mixed solution may preferably be in the range of 0.001 g / L or more and 1000 g / L or less. This range makes it possible to produce diamond particles. The salt concentration in the mixed solution preferably satisfies the range of 0.1 g / L or more and 10 g / L or less. This improves the yield. The salt concentration in the mixed solution more preferably satisfies the range of 0.3 g / L or more and 5 g / L or less. This further improves the yield. The salt concentration in the mixed solution even more preferably satisfies the range of 0.5 g / L or more and 1.5 g / L or less.
[0034] In step S110, it is advisable to use an ultrasonic homogenizer, a high-pressure homogenizer, or the like to ultrasonically disperse the mixture.
[0035] In step S120, aging can be achieved by simply holding the mixed solution, but preferably the mixed solution is held at a temperature between 0°C and 400°C for 0.1 hours to 1000 hours. Diamond particles can be generated within this range. Preferably, the mixed solution is held at a temperature between 10°C and 250°C for 20 hours to 200 hours.
[0036] In step S120, aging may be performed under atmospheric pressure or under the saturated vapor pressure of the selected solvent. Saturated vapor pressure is particularly preferred, as it promotes the generation of diamond particles and allows the retention time to be shortened to a range of 10 to 30 hours. Following step S120, a process may be performed in which the solvent is removed, the product is recovered, and the product is washed. This removes salts.
[0037] Although the inventors of the present invention have not yet elucidated the mechanism by which diamond particles are produced by using a carbon-containing organic solvent and an inorganic salt, they believe that: When the carbon atom in the organic solvent has an sp3 hybrid orbital, or when it is easy to form an sp3 hybrid orbital, the salt as a catalyst pulls out atoms other than carbon bonded to the carbon atom, forming a C-C bond. For example, when the organic solvent has a CH3 group and a chloride is used as the salt, the CH3 in the tetrahedral bond configuration - It is believed that H is replaced by Cl to form CCl4, and Cl is replaced by C to form a diamond structure with a C-C bond.
[0038] The diamond particles of the present invention can be applied to fluorescent semiconductor quantum dots and nanoscale magnetic sensors by utilizing the properties of diamond, but if used for in vivo tracking, it will also enable tracking of stem cell implantation and regenerative ability.
[0039] The present invention will now be described in detail using specific examples, but it should be noted that the present invention is not limited to these examples. [Example]
[0040] [Example 1 to Example 10] In Examples 1 to 10, various carbon-containing solvents and salts shown in Table 1 were used to synthesize diamond particles. FIG. 2 is a diagram showing the procedures of Examples 1 to 10.
[0041] Specifically, a salt shown in Table 1 was added to and mixed with an organic solvent (50 mL) containing the carbon shown in Table 1 to give a predetermined concentration, to obtain a mixed solution (Step S110 in FIG. 1). The mixed solution was aged under the conditions shown in Table 1 (Step S120 in FIG. 1).
[0042] [Table 1]
[0043] The resulting sample was washed multiple times with ethanol and then evaluated using a transmission electron microscope (TEM, JEM-2100F, manufactured by JEOL Ltd.). The results are shown in Figures 3 to 8 and Table 2.
[0044] FIG. 3 shows a TEM image of the diamond particles according to Example 1. FIG. 4 shows a TEM image of the diamond particles according to Example 2.
[0045] As shown in Figures 3 and 4, particles with a black contrast were produced. Figure 3 shows particles with a minimum diameter of 1 nm and a maximum diameter of 60 nm, and Figure 4 shows particles with a diameter of 1 nm to 30 nm. When the average diameters were measured using ImageJ (ver. 1.51n; open source, public domain image processing software), the average diameter of the particles in Example 1 was 8 nm, and the average diameter of the particles in Example 2 was 12 nm. Although not shown, the particles in Examples 3 to 10 also exhibited similar behavior.
[0046] Figure 4 shows the selected area electron diffraction (SAED) pattern of the particles, which showed clear Bragg reflections. Indexing with Miller indices confirmed the {111}, {220}, {311}, {400}, and {331} reflections due to the cubic diamond structure, as well as the {200} reflection. This confirmed that the obtained particles were diamond particles and had a cubic crystal structure. It is presumed that the {200} reflection was an extinction reflection due to the cubic diamond structure of the Fd3-m space group, which appeared due to the multiple scattering effect. It was also confirmed that the diamond particles of Examples 1, 3, and 10 also had a cubic crystal structure.
[0047] FIG. 5 shows HR-TEM images of the diamond particles of Example 1 observed from various crystal orientations. FIG. 6 shows HR-TEM images of diamond particles from Example 2 observed from various crystal orientations.
[0048] Figures 5 and 6A to 6D show HR-TEM images and FFT diffraction patterns of diamond particles along the directions of
[0100] ,
[0110] ,
[0111] and
[0112] , respectively. Figures 5 and 6 show that the diamond particles are single crystals. Although not shown, the diamond particles of Examples 3 to 10 were also single crystals.
[0049] FIG. 7 shows an HR-TEM image of another diamond particle according to Example 2.
[0050] Figures 7A and 7B show the HR-TEM image and FFT diffraction pattern of diamond particles along the
[0100] and
[0001] directions, respectively. Figure 7 shows that hexagonal diamond particles are observed, and that they are single crystal particles with a hexagonal crystal structure. Although not shown, it was also found that some diamond particles in Examples 1 and 3 to 10 also have a hexagonal crystal structure.
[0051] FIG. 8 shows an HR-TEM image of another diamond particle of Example 2.
[0052] Diamond particles having twins and stacking faults were observed, as shown in Figure 8. Although not shown, particles having crystallographic defects were also observed among 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 solvents. The diamond particles thus obtained have clean surfaces and are free of impurities, and can be used in applications such as fluorescent semiconductor quantum dots, nanoscale magnetic sensors, in vivo tracking, and drug delivery.
Claims
1. mixing a solvent containing a carbon-containing organic solvent with a salt to obtain a mixed solution; Aging the mixture. The method of claim 1, further comprising:
2. 2. The method according to claim 1, wherein the organic solvent is at least one 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.
3. The method according to claim 2, wherein the alcohol-based solvent is at least one 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.
4. The method according to claim 2, wherein the ketone solvent is at least one selected from the group consisting of acetone, methyl ethyl ketone, acetylacetone, isopropyl methyl ketone, isobutyl methyl ketone, 2-pentanone, 3-pentanone, cyclohexanone, and diketones.
5. The method according to claim 2, wherein the ester solvent is at least one selected from the group consisting of ethyl acetate, propylene glycol monomethyl ether acetate, and 2-ethoxyethyl acetate.
6. 3. The method according to claim 2, wherein the amide solvent is at least one 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. 3. The method according to claim 2, wherein the hydrocarbon solvent is at least one 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. 3. The method according to claim 2, wherein the aromatic solvent is at least one selected from the group consisting of benzene, toluene, xylene, trimethylbenzene, ethylbenzene, methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene.
9. 3. The method of claim 2, wherein the cellosolve-based solvent is at least one 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. 3. The method of claim 2, wherein the halogen-based solvent is at least one selected from the group consisting of dichloromethane, trichloromethane, carbon tetrachloride, and chloroform.
11. The method according to any one of claims 1 to 10, wherein the salt is at least one selected from the group consisting of metal halides, metal oxyhalides, metal nitrates, metal phosphates, and metal sulfates.
12. 12. The method of claim 11, 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.
13. The method according to any one of claims 1 to 12, 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.
14. The method according to claim 13, wherein the concentration of the salt in the mixture is in the range of 0.3 g / L to 5 g / L.
15. The method according to any one of claims 1 to 14, wherein the aging step comprises holding the mixed solution at a temperature in the range of 0°C to 400°C for a period of 0.1 hours to 1000 hours.
16. The method of claim 15, wherein the aging comprises maintaining the mixture at a temperature in the range of 10° C. to 250° C. for a period of 20 hours to 200 hours.
17. The method according to any one of claims 1 to 16, wherein the aging step comprises holding the mixture under atmospheric pressure or under the saturated vapor pressure of the solvent.
18. having a cubic and / or hexagonal crystal structure; Diamond particles having a particle size in the range of 0.5 nm to 1 mm.
19. 20. Diamond particles according to claim 18, having a particle size in the range of 1 nm to 100 nm.