A method for large-scale regulation of the shape of diamond micro-nanoparticles

Abstract

The application provides a method for large-scale regulation of the shape of diamond micro-nanoparticles, which comprises: air oxidation treatment of chemical vapor deposition grown diamond micro-nanoparticles and / or high-pressure high-temperature grown diamond micro-nanoparticles. The application realizes controllable morphological transformation of diamond micro-nanoparticles through air oxidation, and it has been proved that by adjusting the air oxidation parameters, i.e. temperature and duration, a series of unique shapes can be realized, including flower shape, hollow structure, surface patterned pyramid and boomerang shape. Large-scale production of these different shaped diamond micro-nanoparticles represents a major scientific breakthrough and has high commercial value. The ability to simply and low-cost prepare diamond particles with desired shapes will remove many obstacles for the practical application of diamond in nanophotonics, quantum computing, quantum optics and the like.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a method for large-scale control of the shape of diamond micro- and nano-particles. Background Technology

[0002] The geometry of micron- and nanoparticles (micro- and nanoparticles) is one of the most important parameters for endowing them with functionality; therefore, efforts are focused on achieving shape control. Fabricating shape-variable micron- and nanoparticles is an interesting challenge, requiring the integration of various concepts from multiple disciplines. Furthermore, materials with unique and complex nanostructures possess many functional properties, including targeting capabilities and optical tunability, and the expansion (scaling up) of the designed structures will create even more functional materials with special properties. Therefore, effectively processing micron- and nanoparticles into desired shapes is key to achieving their specific properties.

[0003] Diamond materials possess excellent optical and spectral properties, high thermal conductivity, high mechanical strength, excellent biocompatibility, and flexible surface properties, making them promising for applications in basic science and industry. With the rapid development of synthesis and engineering methods, diamond materials can be processed into different structures according to specific applications. For example, using mature nanofabrication techniques, bulk diamond has been processed into various photonic structures, such as nanowires and nanopillars. Meanwhile, diamond micron and nanoparticles have attracted worldwide attention due to their tunable size (stable color centers can still be accommodated even when reduced to a few nanometers), excellent biocompatibility, and rich surface chemical properties.

[0004] Advanced nanofabrication techniques have the potential to manipulate the shape of individual diamond micro / nanoparticles. However, due to their high hardness, small particle size, irregular shape, chemical inertness, and high cost, there are currently no feasible techniques for large-scale engineering of their shapes (e.g., from typical "polyhedra" to shapes with complex nanostructures). Researchers have recognized the importance of shape control for diamond micro / nanoparticles, for example, through proposed shape-related optical measurements. Unfortunately, due to a lack of technical methods, exploration of shape engineering-based applications is quite limited. Therefore, developing new technologies and processes for the shape engineering of diamond materials, particularly diamond micro / nanoparticles, is crucial for successfully realizing their potential applications in nanomechanics, optomechanics, nanophotonics, quantum computing, and quantum optics. Summary of the Invention

[0005] Therefore, the purpose of this invention is to develop a method for large-scale control of the shape of diamond micro / nanoparticles.

[0006] The term "scalability" as used in this article refers to the ability of this method to simultaneously fabricate multiple (or large quantities) diamond micro / nanoparticles with desired shapes. In contrast, existing nanofabrication techniques can only be used to control or adjust the shape of individual diamond micro / nanoparticles.

[0007] The term "micro-nanoparticles" as used in this document refers to particles with a diameter in the micrometer or nanometer range. For example, the diameter of the micro-nanoparticles can be 10 nm to 10 μm, preferably 100 nm to 2 μm.

[0008] In a first aspect, the present invention provides a method for large-scale control of the shape of diamond micro / nanoparticles, the method comprising: subjecting chemical vapor deposition-grown diamond micro / nanoparticles and / or high-pressure, high-temperature-grown diamond micro / nanoparticles to air oxidation treatment, wherein...

[0009] When the average particle size of the diamond micro / nanoparticles is between 10 nm and 500 nm, air oxidation treatment is performed under one of the following conditions:

[0010] -Oxidize in air at 530-570℃ for 5-25 hours;

[0011] -Oxidize in air at 580~620℃ for 10min~10h;

[0012] When the average particle size of the diamond micro / nano particles is greater than 500 nm to 10 μm, air oxidation treatment is performed under one of the following conditions:

[0013] -Oxidize in air at 580-620℃ for 10-35 hours;

[0014] - Oxidize in air at 630-670℃ for 5-25 hours.

[0015] According to the method provided by the present invention, the diamond micro / nanoparticles grown by high pressure and high temperature (HPHT) can be commercially available diamond micro / nanoparticles with an average particle size ranging from 10 nm to 10 μm, preferably from 100 nm to 2 μm. The diamond micro / nanoparticles grown by chemical vapor deposition can be diamond micro / nanoparticles prepared by chemical vapor deposition (CVD) using commercially available high pressure and high temperature grown diamond micro / nanoparticles as raw materials, with an average particle size typically from 500 nm to 10 μm, preferably 1 to 2 μm.

[0016] In some embodiments of the present invention, the method for preparing the diamond micro / nanoparticles grown by chemical vapor deposition includes the following steps:

[0017] (1) The diamond micro-nano particles grown under high pressure and high temperature are mixed with sodium chloride and heated in air at 400-600℃ for 0.5-2h; the product is dispersed in deionized water, sonicated and purified by centrifugation in deionized water 1-5 times, and then redispersed in deionized water and sonicated for 1-3 hours to obtain a suspension of diamond micro-nano particles.

[0018] (2) The suspension obtained in step (1) is spin-coated onto a standard single-crystal Si substrate treated with hydrogen plasma, and then placed in a microwave plasma-assisted chemical vapor deposition system to grow diamond micro and nanoparticles by introducing a mixed gas of H2 and methane.

[0019] The average particle size of the diamond micro-nanoparticles grown under high pressure and high temperature in step (1) is preferably 50 nm to 200 nm.

[0020] Preferably, the average particle size of the diamond micro / nanoparticles grown in step (2) is 1–2 μm.

[0021] The second aspect of the present invention provides a method for large-scale preparation of diamond microparticles with a flower-like morphology, the method comprising subjecting diamond micro / nanoparticles grown by chemical vapor deposition with an average particle size of 1-2 μm to air oxidation treatment under the following conditions: oxidation in air at 580-620°C for 25-35 h.

[0022] The third aspect of the present invention provides a method for large-scale preparation of diamond microparticles with a pyramidal pattern on the surface, the method comprising subjecting diamond micro / nanoparticles grown by chemical vapor deposition with an average particle size of 1-2 μm to air oxidation treatment under the following conditions: oxidation in air at 580-620°C for 10-20 h.

[0023] The fourth aspect of the present invention provides a method for large-scale preparation of diamond microparticles with hollow structures, the method comprising subjecting diamond micro / nanoparticles grown by chemical vapor deposition with an average particle size of 1-2 μm to air oxidation treatment under the following conditions: oxidation in air at 630-670°C for 15-25 h.

[0024] The fifth aspect of this invention provides a method for the large-scale preparation of diamond nanoparticles with a pyramidal pattern on their surface, the method comprising subjecting diamond micro / nanoparticles grown under high pressure and high temperature with an average particle size of 100–500 nm to air oxidation treatment under one of the following conditions:

[0025] -Oxidize in air at 530-570℃ for 5-25 hours;

[0026] - Oxidize in air at 580~620℃ for 30min~5h.

[0027] The sixth aspect of the present invention provides a method for the large-scale preparation of diamond microparticles with a boomerang-shaped morphology, the method comprising subjecting diamond micro / nanoparticles grown under high pressure and high temperature with an average particle size of 500 nm to 2 μm to air oxidation treatment under the following conditions: oxidation in air at 580 to 620 °C for 10 to 30 h.

[0028] This invention achieves controllable morphological transformation of diamond micro / nanoparticles through air oxidation, and it has been demonstrated that a series of unique shapes, including flower-shaped, hollow structures, surface-patterned pyramids, and boomerang shapes, can be achieved by adjusting the air oxidation parameters, namely temperature and duration. The large-scale production of these diverse diamond micro / nanoparticle shapes represents a significant scientific breakthrough with high commercial value. The ability to easily and cost-effectively prepare diamond particles of desired shapes will remove many obstacles to the practical applications of diamond in nanophotonics, quantum computing, and quantum optics. Attached Figure Description

[0029] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0030] Figure 1 The images shown are scanning electron microscope (SEM) images (a), Raman spectra (b), and X-ray diffraction (XRD) results (c) of the CVD diamond microparticles prepared in Example 1 of this invention.

[0031] Figure 2 The images shown are SEM images (a), Raman spectra (b), and XRD results (c) of the flower-shaped CVD diamond microparticles obtained in Example 2 of this invention.

[0032] Figure 3 This is a SEM image of CVD diamond microparticles with a "pyramid" pattern on their surface, obtained in Example 3 of the present invention.

[0033] Figure 4 This is a SEM image of CVD diamond microparticles with a "hollow" structure obtained in Example 4 of the present invention.

[0034] Figure 5 Figure 5 shows SEM images of CVD-grown diamond microparticles obtained in Example 5 (Figure 5a) and SEM images of CVD diamond microparticles with a densely packed "hollow" structure after air oxidation (Figure 5b).

[0035] Figure 6 The images show SEM and transmission electron microscopy (TEM) images of the raw material HPHT diamond nanoparticles in Example 6 and the HPHT diamond nanoparticles after being treated in four different ways.

[0036] Figure 7The images show TEM images of the raw material HPHT diamond nanoparticles in Example 7 and the HPHT diamond nanoparticles after being treated in three different ways.

[0037] Figure 8 Selected region electron diffraction (SAED) patterns and corresponding TEM images of HPHT diamond nanoparticles (a) oxidized in air at 600°C for 2 hours in Example 6 and HPHT diamond nanoparticles (b) oxidized in air at 600°C for 15 hours in Example 7. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0039] Example 1

[0040] Preparation of CVD diamond microparticles

[0041] (1) 0.1 g of diamond nanoparticles (50 nm NDs, HPHT, PolyQolor, China) were mixed with 0.5 g of sodium chloride (NaCl, 99.5%, Sigma-Aldrich) and heated in air at 500 °C for 1 h. The sample was dispersed in 100 mL of deionized water and sonicated for 1 h, then purified three times by centrifugation with deionized water. The purified NDs were redispersed in deionized water and sonicated for 2 h to obtain a well-dispersed NDs suspension (~1 mg / mL), which was used for CVD diamond growth.

[0042] (2) Before CVD growth, the silicon (Si) substrate was subjected to hydrogen plasma treatment for 10 minutes in a microwave plasma-assisted chemical vapor deposition (MPCVD) system (Seki 6350, power 1300W, chamber pressure 35 torr, hydrogen H2 flow rate: 300 sccm). Then, 3 drops (50 μL) of NDs suspension were spin-coated onto a standard single-crystal Si (100) wafer (2 inches) treated with hydrogen plasma. The above spin-coating process was repeated 5 times.

[0043] (3) Place the spin-coated Si substrate with NDs into the MPCVD system and grow diamond for 80 minutes under fixed power (3400W), pressure (85 torr) and temperature (920℃) conditions by introducing a mixed gas of H2 (gas flow rate 485sccm) and methane (CH4, gas flow rate 15sccm).

[0044] Figure 1The images show scanning electron microscopy (SEM) images (a), Raman spectra (b), and X-ray diffraction (XRD) results (c) of the prepared diamond microparticles. The SEM images show that the CVD-grown diamond microparticles have clear crystal faces and a particle size range of 1–2 μm; the Raman spectra show a particle size at 1333 cm⁻¹. -1 A clear diamond Raman peak was observed, with no significant contribution from graphite or amorphous carbon. X-ray diffraction results also indicated the pure crystalline nature of the diamond microparticles, with only characteristic peaks from the diamond (111) plane (43.9°) and the silicon substrate detected in the XRD spectrum. These results demonstrate the high crystalline quality of the prepared CVD diamond microparticles.

[0045] Example 2

[0046] Preparation of CVD diamond microparticles with flower-like morphology

[0047] The CVD diamond microparticles grown in Example 1 were oxidized in air at 600°C for 30 hours to obtain diamond microparticles with a flower-like morphology.

[0048] Figure 2 SEM image (Figure a), Raman spectrum (Figure b), and XRD results (Figure c) of flower-shaped CVD diamond microparticles obtained by air oxidation are shown. The SEM image reveals a clear "flower" shape within the CVD diamond microparticles; that is, the previously flat surface is etched with numerous concave surfaces to form a "flower" shape. The Raman and XRD spectra clearly demonstrate the high crystallinity of the "flower"-shaped CVD diamond microparticles, with no significant impurity contribution.

[0049] Example 3

[0050] Preparation of CVD diamond microparticles with a "pyramid" pattern on the surface

[0051] The CVD diamond microparticles grown in Example 1 were oxidized in air at 600°C for 15 hours to obtain diamond microparticles with a "pyramid" pattern on the surface.

[0052] Figure 3 SEM image of CVD diamond microparticles with a "pyramid" pattern on the surface, obtained by air oxidation. Figure 3 The diamond microparticles show that their surface has multiple protrusions in the shape of "nanopyramids" (50-100 nm in diameter).

[0053] Example 4

[0054] Preparation of CVD diamond microparticles with a "hollow" structure

[0055] The CVD diamond microparticles grown in Example 1 were oxidized in air at 650°C for 20 hours to obtain diamond microparticles with a "hollow" structure.

[0056] Figure 4 SEM image of CVD diamond microparticles with a "hollow" structure obtained by air oxidation. Figure 4 The diamond microparticles show a clear "hollow" structure, meaning that some of the internal structure has been oxidized.

[0057] Example 5

[0058] Preparation of densely packed "hollow" structured CVD diamond microparticles

[0059] The CVD diamond microparticles grown according to the method of Example 1 differed in that the spin coating process in step (2) was repeated 15 times.

[0060] The prepared CVD diamond microparticles were oxidized in air at 650°C for 20 hours to obtain densely packed "hollow" structured diamond microparticles.

[0061] Figure 5 Figure 1 shows an SEM image of the CVD-grown diamond microparticles obtained in this embodiment (Figure 1a) and an SEM image of the CVD diamond microparticles with a densely packed "hollow" structure after air oxidation (Figure 2b).

[0062] SEM image of densely packed, hollow CVD diamond microparticles. Figure 5 The densely packed diamond microparticles exhibit a distinct "hollow" structure, meaning that some of the internal structure has been oxidized.

[0063] Example 6

[0064] Preparation of HPHT diamond nanoparticles with a "pyramid" pattern on the surface

[0065] Diamond nanoparticles with an average particle size of 200 nm (HPHT, PolyQolor, China) were used as raw materials and subjected to air oxidation treatment in the following ways:

[0066] (i) Heat in air at 550°C for 10 hours;

[0067] (ii) Heat in air at 550°C for 20 hours;

[0068] (iii) Heat in air at 600°C for 1 hour;

[0069] (iv) Heat in air at 600°C for 2 hours.

[0070] Figure 6The images shown are SEM and TEM images of the raw HPHT diamond nanoparticles and the HPHT diamond nanoparticles treated by four different methods in this embodiment. Image (a) shows the raw HPHT diamond nanoparticles, and images (b)-(e) show the HPHT diamond nanoparticles obtained by the above treatment methods (i)-(iv), respectively. Figure 6 As shown, all four different treatments can transform the originally fragmented diamond nanoparticles into diamond nanoparticles with a pyramid-shaped (5-20 nm in diameter) pattern on the surface.

[0071] Example 7

[0072] Preparation of HPHT diamond nanoparticles with a boomerang-shaped morphology

[0073] Diamond nanoparticles with an average particle size of 1 μm (HPHT, PolyQolor, China) were used as raw materials and subjected to air oxidation treatment in the following manner:

[0074] (i) Heat in air at 600°C for 15 hours.

[0075] (ii) Heat in air at 600°C for 20 hours.

[0076] (iii) Heat in air at 600°C for 25 hours.

[0077] Figure 7 These are TEM images of the raw HPHT diamond nanoparticles and the HPHT diamond nanoparticles treated by three different methods in this embodiment. Image (a) shows the raw HPHT diamond nanoparticles, and images (b)-(d) show the HPHT diamond nanoparticles obtained by the above treatment methods (i)-(iii), respectively. Figure 7 As shown, all three different processing methods can change the fragmented shape of the original diamond microparticles into a "boomerang" shape.

[0078] Figure 8 Selected region electron diffraction (SAED) patterns and corresponding TEM images of HPHT diamond nanoparticles (a) oxidized in air at 600°C for 2 hours in Example 6 and HPHT diamond nanoparticles (b) oxidized in air at 600°C for 15 hours in this example. Figure 8 It is clearly shown that, despite the obvious changes in morphology, the (111), (220), and (311) crystal planes of diamond did not change after air oxidation treatment.

[0079] This invention provides a simple and effective method for arbitrary morphology modulation of CVD and HPHT-grown diamond micron and nanoparticles through air oxidation treatment. For example, by fine-tuning the air oxidation parameters (i.e., temperature and duration), CVD and HPHT diamond micron and nanoparticles with "flower-like," "hollow," surface "pyramid" patterns, and "boomerang" shapes have been successfully achieved. These methods represent a significant scientific breakthrough and have high commercial value. They enable the simple and low-cost preparation of diamond particles with desired shapes, removing many obstacles for the practical applications of diamond in nanophotonics, quantum computing, and quantum optics.

[0080] The above embodiments are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall not depart from the technical solutions of the present invention and shall still fall within the protection scope of the present invention.

Claims

1. A method for large-scale preparation of diamond micro / nanoparticles with flower-like morphology or hollow structure, the method comprising: The diamond micro / nanoparticles grown by chemical vapor deposition were subjected to air oxidation treatment, wherein: The method for preparing diamond microparticles with flower-like morphology includes oxidizing diamond micro / nanoparticles grown by chemical vapor deposition with an average particle size of 1-2 μm in air under the following conditions: oxidizing in air at 580-620℃ for 25-35 h. The method for preparing diamond microparticles with hollow structures includes oxidizing diamond micro / nanoparticles grown by chemical vapor deposition with an average particle size of 1-2 μm in air under the following conditions: oxidizing in air at 630-670°C for 15-25 h. The method for preparing the diamond micro / nanoparticles grown by chemical vapor deposition includes: (1) The diamond micro-nanoparticles grown under high pressure and high temperature are mixed with sodium chloride and heated in air at 400~600℃ for 0.5~2 h; the product is dispersed in deionized water, sonicated and purified by centrifugation in deionized water 1~5 times, and then redispersed in deionized water and sonicated for 0.5~3 h to obtain a suspension of diamond micro-nanoparticles. (2) The suspension obtained in step (1) is spin-coated onto a standard single-crystal Si substrate treated with hydrogen plasma, and then placed in a microwave plasma-assisted chemical vapor deposition system to grow diamond micro and nanoparticles by introducing a mixed gas of H2 and methane.

2. The method of claim 1, wherein, The average particle size of the diamond micro-nanoparticles grown in step (2) of the method for preparing diamond micro-nanoparticles by chemical vapor deposition is 1~2μm.

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