Nanodiamonds and methods for their production

Abstract

The application provides a kind of nanodiamond and its preparation method, comprising the following steps: solid aromatic hydrocarbon is placed in the sample bin of multi-face anvil press, and is pressurized to 14-16GPa;Then, heat to 1100-1600℃, keep pressure for 0.5-2h;Finally, cool to room temperature, to obtain the nanodiamond.The preparation method of a kind of nanodiamond of the application is simple, the whole synthesis process is only through one pressurization, heating process, time-saving and low energy consumption, reduces the preparation cost.The particle size of the nanodiamond prepared by the application is less than 10nm, and can even reach about 2nm, and the synthesized nanodiamond product does not contain amorphous carbon and metal impurities, and has high purity.

Description

Technical Field

[0001] This application belongs to the field of diamond synthesis technology, and more specifically, relates to a nanodiamond and its preparation method. Background Technology

[0002] Diamond is the hardest known material in nature, possessing excellent mechanical, thermal, electrical, and optical properties. It exhibits high thermal conductivity, an extremely low coefficient of thermal expansion, a low coefficient of friction, and good chemical stability at room temperature. It has wide applications in industries such as wire drawing dies, cutting tools, drill bits, and abrasives. When diamond is processed at the nanoscale, it exhibits physical effects that are not present at the macroscopic level or are negligible therein, such as superelasticity and quantum sensing capabilities. These have important applications in high-tech fields such as nanoelectronics, precision instruments, and biomedicine, including lubrication, drug delivery, energy storage, catalysis, optical devices, and, in recent years, the use of its quantum sensing properties for medical diagnostics. These high-precision applications also place demands on the preparation of high-purity nanodiamonds. Therefore, the synthesis methods of diamond, especially methods for preparing high-purity, small-particle-size diamonds free from amorphous carbon, metals, and other impurities, have always been a hot topic of research.

[0003] Currently, there are two main methods for synthesizing diamond under high temperature and high pressure: detonation under dynamic high pressure and static high temperature and high pressure. These two methods can convert carbon-containing starting materials (such as graphite and CH compounds) into diamond. For example, Chinese patent CN1187263C discloses a method for synthesizing nanodiamonds using explosive detonation. TNT (trinitrotoluene, TNT) and RDX (cyclotrimethylenetrinitramine, RDX) are mixed in a ratio of 0.05:0.95, heated in a water bath at 50-95℃ to melt them, cast into explosive charges, and then assembled with detonators to form a detonating charge. This charge is then placed in a steel explosive container filled with a protective atmosphere (argon, nitrogen, etc.) and detonated. After sieving or settling and drying at 100-200℃, detonation ash is obtained. Secondary purification of the detonation ash yields diamonds with a particle size distribution of 1-50 nm, but with low purity and uneven particle size. Chinese patent CN115318204A discloses a method for artificially synthesizing diamond, which uses graphite, catalyst (Ni, Mn, Co, Ge alloy catalyst), and sintering aid (B, Ti) in a mass ratio of 1-2:1-2:0.01-0.1. After self-propagating high-temperature sintering in a tube furnace at 960-1000℃, it is reduced at 1050-1100℃ for 18-24 hours, and then synthesized under high temperature and high pressure using a six-sided top press. First, pressurize to 1-2 GPa, then heat to 500-600℃ and maintain this temperature and pressure for 30-50 minutes. Next, pressurize again to 4-4.5 GPa, then maintain the pressure and heat to 1250-1280℃, holding this high-temperature, high-pressure state for 18-24 hours. Then, depressurize and cool to 0.5-0.75 GPa and 300-350℃ within 3-5 hours, maintaining this temperature and pressure for 2-4 hours to restore normal pressure, and then allow it to cool naturally to room temperature. The synthetic diamond process is cumbersome, time-consuming, and contains impurities such as metals, resulting in low purity and making it unsuitable for synthesizing nanodiamonds.

[0004] While the above-mentioned methods for synthesizing diamond can yield diamonds, they all have significant drawbacks: the synthesis steps are cumbersome and costly, resulting in nanodiamonds with large and uneven particle sizes; or the purity of the nanodiamonds obtained is low, containing impurities such as amorphous carbon and metals. Furthermore, although the detonation method produces nanodiamonds with small particle sizes, product quality is difficult to control, purity is low, and the product requires post-processing purification, which generates industrial waste gas. The process is complex, and unsuitable temperatures can easily produce impurities such as insoluble chromates, making it difficult to extract a pure product. Therefore, finding a relatively simple process to synthesize small-particle-size nanodiamonds free from metal catalysts and amorphous carbon impurities is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a nanodiamond and its preparation method, so as to solve at least one of the technical problems in the prior art, such as low purity, large and uneven particle size, and cumbersome synthesis steps and high cost of synthesized nanodiamonds.

[0006] To achieve the above objectives, a first aspect of this application provides a method for preparing nanodiamonds, comprising the following steps:

[0007] Solid aromatic hydrocarbons were placed in the sample chamber of a multifaceted anvil press and pressurized to 14-16 GPa; then heated to 1100-1600℃ and held at that temperature and pressure for 0.5-2 hours; finally cooled to room temperature to obtain the nanodiamonds.

[0008] Furthermore, the solid aromatic hydrocarbon is at least one of trans-stilbene and polystyrene.

[0009] Furthermore, the multi-faceted anvil press is a Walker-type 1000-ton multi-faceted anvil press.

[0010] Furthermore, the pressurization speed is 20-30% RPM.

[0011] Furthermore, after cooling to room temperature, the depressurization speed is 2-3% RPM.

[0012] Furthermore, the heating rate is 50-100℃ / min.

[0013] Furthermore, the cooling and quenching rate is 300-500℃ / s.

[0014] Furthermore, the sample chamber is made of gold.

[0015] Furthermore, the sample chamber is cleaned before use.

[0016] Furthermore, the cleaning process is performed using ultrasound.

[0017] In a second aspect, this application provides a nanodiamond obtained by the preparation method described above.

[0018] Compared with the prior art, this application has the following technical effects:

[0019] The present application discloses a method for preparing nanodiamonds. The process is simple, and the entire synthesis process only involves one step of pressurization and heating, which saves time and has low energy consumption, thereby reducing the preparation cost.

[0020] The nanodiamonds prepared in this application have a particle size of <10nm, and can even reach about 2nm. Moreover, the synthesized nanodiamond products do not contain amorphous carbon and metal impurities, and have high purity. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 These are micrographs of the nanodiamond product prepared in Example 1 of this application;

[0023] Figure 2 The Raman spectrum of the nanodiamond product prepared in Example 1 of this application;

[0024] Figure 3 The X-ray diffraction pattern of the nanodiamond product prepared in Example 1 of this application;

[0025] Figure 4 The Raman spectrum of the nanodiamond product prepared in Example 2 of this application;

[0026] Figure 5 The X-ray diffraction pattern of the nanodiamond product prepared in Example 2 of this application;

[0027] Figure 6 The X-ray diffraction pattern of the nanodiamond product prepared in Example 3 of this application is shown. Detailed Implementation

[0028] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0029] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0030] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0031] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0032] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0033] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0034] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0035] A first aspect of this application provides a method for preparing nanodiamonds, comprising the following steps:

[0036] Solid aromatic hydrocarbons are placed in the sample chamber of a multifaceted anvil press and pressurized to 14-16 GPa; then the temperature is raised to 1100-1600℃ and held at the temperature and pressure for 0.5-2 hours; finally, the temperature is lowered to room temperature and the pressure is released to obtain the nanodiamond.

[0037] The room temperature in this application embodiment refers to 20-35℃.

[0038] The method for preparing nanodiamonds according to the embodiments of this application is simple, and the entire synthesis process only requires one step of pressurization and heating, which saves time and has low energy consumption, thereby reducing the preparation cost.

[0039] In the embodiments of this application, the solid aromatic hydrocarbon used is at least one of trans-stilbene and polystyrene.

[0040] The multi-faceted anvil press used in this embodiment is a Walker-type 1000-ton multi-faceted anvil press. To avoid damage to the tungsten carbide pressure transmission cube in the Walker-type 1000-ton multi-faceted anvil press due to excessively rapid pressurization during the pressurization process, the pressurization speed is controlled at 20-30% RPM in this embodiment. After cooling to room temperature, the depressurization speed is 2-3% RPM, and the synthesized diamond product is removed after the pressure is released.

[0041] The heating rate in this embodiment is controlled at 50-100℃ / min to prevent excessively rapid heating, which could damage the heating furnace or anvil.

[0042] The cooling and quenching rate of this application embodiment is 300-500℃ / s, and the synthesized high-pressure phase, i.e. nano-diamond product, is preserved by rapid cooling.

[0043] The sample chamber used in this embodiment is made of gold. Gold has good chemical stability, no catalytic effect, and will not react chemically with the starting sample, thus avoiding the introduction of impurities. The sample chamber in this embodiment is a cylindrical container made of metallic gold, and the size of the gold sample chamber can be 2.0 mm in outer diameter × 1.8 mm in height. The metallic gold tube is cut to the appropriate length, and then a circular gold sheet with a thickness of 0.15 mm is welded to the top and bottom ends of the gold tube using a welding laser to seal the gold tube.

[0044] The sample chamber in this embodiment is cleaned before use to remove debris and prevent the introduction of impurities. Specifically, the cleaning process is performed ultrasonically, by placing the gold sample chamber in water under 60Hz ultrasound for 5-10 minutes to ensure its cleanliness.

[0045] Furthermore, the sample chamber in this embodiment can be filled with either powdered or lumpy raw materials. For powdered raw materials, they should be ground before loading, with the particle size being as small as possible. Compacting smaller particle sizes allows for better filling of the sample chamber, preventing severe deformation of the sample chamber under high pressure due to sample looseness, which could lead to breakage of the Re plate in the heating furnace and experimental failure. For lumpy samples, there are no particle size requirements, and they can be processed into sample columns of the same size as the sample chamber. During grinding and loading, it is crucial to avoid the introduction of particulate impurities, which could result in an impure synthesis product.

[0046] In a second aspect, this application provides a nanodiamond obtained by the preparation method described above.

[0047] The nanodiamonds prepared in the embodiments of this application have a particle size of <10nm, and can even reach about 2nm. Moreover, the synthesized nanodiamond products do not contain amorphous carbon and metal impurities, and have high purity.

[0048] The following examples illustrate a nanodiamond and its preparation method according to embodiments of this application.

[0049] Example 1

[0050] Example 1 of this application provides a nanodiamond and its preparation method, including the following steps:

[0051] Take an appropriate amount of trans-stilbene (C 14 H 12 The sample was cut into 1.5mm long gold tubes. A 0.15mm thick circular gold sheet was laser-welded to one end of the tube to seal it. The diameter of the circular gold sheet should be the same as that of the gold tube. The gold sample chamber was then ultrasonically cleaned in water at 60Hz for 5-10 minutes. The sample was then ground in an agate mortar for 15 minutes to make the powder fine. The sample was then placed into the gold sample chamber, and the other end of the gold tube was sealed with a circular gold sheet of the same size. High-temperature and high-pressure synthesis was performed using a Walker-type 1000-ton multi-faceted anvil press. Assembly was performed using a COMPRES 10 / 5 assembly machine. The pressurization speed was 30% RPM, and the pressure was increased to 15.5 GPa. The temperature was then increased by 100°C every 1.5 minutes until it reached 1600°C, and maintained at 15.5 GPa and 1600°C for 1 hour. Then, the temperature was slowly lowered to room temperature, the pressure was released, the assembly residue was removed, and the sample chamber was polished (the gold sample chamber was ultrasonically cleaned in water at 60 Hz for 5 minutes, then coarsely ground with 100-200 grit silicon carbide sandpaper until the synthesized product was exposed; then finely ground with 600-1200 grit silicon carbide sandpaper to smooth the surface and increase the exposed area) to obtain the nanodiamond product.

[0052] Figure 1 This is a micrograph of the nanodiamond product prepared in the embodiments of this application.

[0053] Figure 2 The image shows the Raman spectrum of the nanodiamond product prepared in the embodiments of this application. Figure 3 X-ray diffraction pattern of the nanodiamond product prepared in the embodiments of this application. Figure 3The nanodiamond product exhibits distinct diamond characteristic peaks (111), (220), and (311). The particle size of the nanodiamond product was calculated to be 6.4 ± 1.4 nm based on the (111) and (220) characteristic peaks. Furthermore, Raman spectroscopy and X-ray diffraction patterns show that the nanodiamond phase prepared in this application is pure, requires no post-processing, and contains no amorphous carbon or metal impurities, indicating high product purity.

[0054] Example 2

[0055] Example 2 of this application provides a nanodiamond and its preparation method, including the following steps:

[0056] Take an appropriate amount of trans-stilbene (C 14 H 12 The sample was cut into 1.5mm long gold tubes. A 0.15mm thick circular gold sheet was laser-welded to one end of the tube to seal it. The diameter of the circular gold sheet should be the same as that of the gold tube. The gold sample chamber was then ultrasonically cleaned in water at 60Hz for 5 minutes. The sample was then ground in an agate mortar for 15 minutes to obtain a fine powder. The sample was then placed into the gold sample chamber, and the other end of the gold tube was sealed with a circular gold sheet of the same size. High-temperature and high-pressure synthesis was performed using a Walker-type 1000-ton multi-faceted anvil press. Assembly was performed using a COMPRES 10 / 5, with a rotation speed of 30% RPM and a pressure of 15.5 GPa. The temperature was then increased by 100°C every 1.5 minutes until it reached 1200°C, and maintained at 15.5 GPa and 1200°C for 1 hour. Then, the temperature was slowly lowered to room temperature, the pressure was released, the assembly residue was removed, and the sample chamber was polished (the gold sample chamber was ultrasonically cleaned in water at 60 Hz for 5 minutes. Then, it was coarsely polished with 100-200 grit silicon carbide sandpaper until the synthesized product was exposed; then, it was finely polished with 600-1200 grit silicon carbide sandpaper to smooth the surface and increase the exposed area) to obtain the nanodiamond product.

[0057] Figure 4 The image shows the Raman spectrum of the nanodiamond product prepared in the embodiments of this application. Figure 5 X-ray diffraction pattern of the nanodiamond product prepared in the embodiments of this application. Figure 5 The nanodiamond product exhibited distinct diamond characteristic peaks (111), (220), and (311). The particle size of the nanodiamond product was calculated to be 2.6 ± 0.1 nm based on the (111) and (220) characteristic peaks. Raman spectroscopy indicated the presence of a small amount of hydrocarbons in the nanodiamond product prepared in the embodiments of this application.

[0058] Example 3

[0059] Example 3 of this application provides a nanodiamond and its preparation method, including the following steps:

[0060] Take an appropriate amount of polystyrene (C8H8). n The sample was prepared by cutting a 1.5 mm long gold tube. A 0.15 mm thick circular gold sheet was laser-welded to one end of the tube to seal it. The diameter of the circular gold sheet should be the same as that of the gold tube. The sample chamber was then ultrasonically cleaned in water at 60 Hz for 5 minutes. The sample was then ground in an agate mortar for 15 minutes to obtain a fine powder. The sample was then placed into the gold sample chamber, and the other end of the gold tube was sealed with a circular gold sheet of the same size. High-temperature and high-pressure synthesis was performed using a Walker-type 1000-ton multi-faceted anvil press. Assembly was performed using a COMPRES 10 / 5, with a rotation speed of 30% RPM and a pressure of 15.5 GPa. The temperature was then increased by 100°C every 1.5 minutes until it reached 1100°C, and maintained at 15.5 GPa and 1100°C for 1 hour. Then, the temperature was slowly lowered to room temperature, the pressure was released, the assembly residue was removed, and the sample chamber was polished (the gold sample chamber was ultrasonically cleaned in water at 60 Hz for 5 minutes. Then, it was coarsely polished with 100-200 grit silicon carbide sandpaper until the synthesized product was exposed; then, it was finely polished with 600-1200 grit silicon carbide sandpaper to smooth the surface and increase the exposed area) to obtain the nanodiamond product.

[0061] The Raman spectra of the nanodiamond products prepared in this embodiment are similar to those in Example 2, indicating that a small amount of hydrocarbons are also present in the nanodiamond products prepared in this embodiment. X-ray diffraction pattern ( Figure 6 It is also similar to Example 2. from Figure 6 The nanodiamond product was observed to have obvious diamond (111), (220), and (311) characteristic peaks. The particle size of the nanodiamond product was calculated to be 2.32 ± 0.6 nm based on the (111) and (220) characteristic peaks.

[0062] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing nanodiamond, characterized in that, Includes the following steps: Solid aromatic hydrocarbons were placed in the sample chamber of a multi-faceted anvil press and pressurized to 14-16 GPa; then heated to 1100-1600 ℃ and held at that temperature and pressure for 0.5-2 h; finally cooled to room temperature to obtain the nanodiamonds. The solid aromatic hydrocarbon is at least one of trans-stilbene and polystyrene; The pressurization speed is 20-30% RPM; After cooling to room temperature, the depressurization speed is 2-3% RPM; The heating rate is 50-100 ℃ / min; The cooling and quenching rate is 300-500 ℃ / s; The sample chamber is made of gold.

2. The method for preparing nanodiamond as described in claim 1, characterized in that, The multi-faceted anvil press is a Walker-type 1000-ton multi-faceted anvil press.

3. The method for preparing nanodiamond as described in claim 1, characterized in that, The sample chamber is cleaned before use.

4. The method for preparing nanodiamond as described in claim 3, characterized in that, The cleaning process is performed using ultrasound.

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