Two-dimensional silicon carbide sheet and ultrasonic ball milling preparation method thereof

Abstract

The invention belongs to the technical field of two-dimensional material preparation, and particularly discloses a two-dimensional silicon carbide sheet and an ultrasonic ball milling preparation method thereof.The method comprises the following steps that S1, silicon carbide powder, a grinding medium and an organic solvent are taken and mixed, and a mixture is obtained; synchronously carrying out ultrasonic ball milling in a vacuum or inert gas environment to obtain a supernatant liquid; s2, centrifuging the supernatant liquid to obtain supernatant liquid containing two-dimensional silicon carbide; and S3, putting the supernatant containing the two-dimensional silicon carbide into a vacuum box, and drying to obtain the two-dimensional silicon carbide sheet. According to the two-dimensional silicon carbide sheet and the ultrasonic ball-milling preparation method thereof, the energy of a grinding medium is effectively transferred to a material through collaborative ultrasonic and ball-milling, so that the controllability and repeatability in the preparation process of the two-dimensional silicon carbide sheet are improved, and the quality and grinding efficiency of a product are improved; and a feasible path is provided for large-scale preparation of the two-dimensional silicon carbide sheet.

Description

Technical Field

[0001] This invention belongs to the field of two-dimensional material preparation technology, specifically relating to a two-dimensional silicon carbide sheet and its ultrasonic ball milling preparation method. Background Technology

[0002] As semiconductor material technology advances, silicon-based devices are nearing the limits of Moore's Law, requiring even thinner materials for smaller devices. Reducing the channel width of field-effect transistors to sub-1 nm would drastically increase charge carrier scattering at the channel-dielectric interface, leading to a significant decrease in the mobility of three-dimensional semiconductor crystals. Two-dimensional semiconductors possess ultra-thin thickness, atomic-level flatness, and excellent electronic properties, giving them a natural advantage in minimizing short-channel effects (SCEs) and addressing the scaling problem of three-dimensional semiconductors. The discovery of graphene sparked a research boom in a class of materials known as "two-dimensional materials." Graphene, composed of hexagonal carbon atoms, does not bond with external atoms in directions perpendicular to the two-dimensional plane, a key advantage distinguishing it from three-dimensional materials. The discovery of two-dimensional materials has broken through the limits of three-dimensional materials, bringing significant opportunities for semiconductor development. However, due to its "zero bandgap" characteristic, graphene is currently unable to be used in the manufacture of large-scale digital circuit devices.

[0003] Silicon carbide, a typical representative of third-generation wide-bandgap semiconductor materials, has demonstrated enormous application potential in semiconductor devices, high-temperature electronics, and power devices since its discovery in the 19th century, thanks to its excellent physicochemical properties. Silicon carbide possesses characteristics such as a high critical breakdown electric field, high electron saturation drift velocity, and high thermal conductivity. Compared to traditional silicon-based materials, it can withstand higher voltage, current density, and operating temperature, effectively improving the performance and efficiency of power devices while reducing energy consumption. With continuous technological advancements, research on silicon carbide materials has gradually expanded from bulk materials to low-dimensional structures, giving rise to two-dimensional silicon carbide, which has become a research hotspot in materials science. Despite the numerous superior properties and broad application prospects of two-dimensional silicon carbide, some challenges remain in its research and application. The preparation technology for high-quality, large-area two-dimensional silicon carbide still needs further optimization and improvement to reduce costs, increase production efficiency, and ensure product quality consistency.

[0004] Currently, the main methods for preparing two-dimensional materials are divided into top-down and bottom-up methods. Bottom-up methods primarily include chemical vapor deposition (CVD) and solvothermal methods. While CVD can produce high-quality two-dimensional materials, the expensive equipment and demanding preparation conditions result in relatively high production costs, hindering large-scale production and subsequent applications. Solvothermal methods, although lower in cost and higher in yield, occur in an autoclave, leaving the growth mechanism of two-dimensional silicon carbide unknown. Top-down methods mainly include micromechanical exfoliation and liquid-phase exfoliation. These techniques overcome interlayer forces, making it easier to prepare high-quality two-dimensional materials suitable for large-scale production. Since three-dimensional silicon carbide is not a van der Waals layered material, adjacent atoms in silicon carbide are connected by covalent sp... 3 The hybrid structure makes it impossible to obtain two-dimensional sheet-like silicon carbide through simple mechanical exfoliation alone. Furthermore, three-dimensional silicon carbide exists in over 250 polymorphs, further complicating the preparation of two-dimensional silicon carbide. Finding a suitable exfoliation method to transform three-dimensional silicon carbide from a wurtzite structure to a graphite-like structure has become a key preparation challenge.

[0005] Liquid-phase ultrasonic exfoliation, unlike micromechanical exfoliation, involves exfoliation through a relatively gentle ultrasonic process within a solvent system. This method is simple, but the yield of the produced two-dimensional materials is low, and there are many defects. For example, Chinese invention patent CN118324138A, a method for preparing two-dimensional layered silicon carbide semiconductor material, involves placing a silicon source and a metal carbide in an organic solvent and subjecting them to ultrasonic treatment in a water bath for 1-36 hours, resulting in a two-dimensional layered silicon carbide structure. Chinese invention patent CN116692866A, a method for preparing two-dimensional layered silicon carbide, involves dispersing expanded silicon carbide in an organic medium and subjecting it to ultrasonic treatment for 0.5-24 hours to obtain two-dimensional layered silicon carbide. Although the liquid-phase ultrasonic exfoliation method disclosed in the above patents is simple, the yield of the prepared two-dimensional materials is low, and there are many defects.

[0006] Ball milling is one method for preparing two-dimensional materials. In conventional ultrasonic ball milling, the friction and impact forces of the grinding media break down particles into smaller particles during the exfoliation process, resulting in large-area exfoliation of the two-dimensional material. However, the impact force can further damage the two-dimensional sheets, leading to reduced yield and defects. Chinese invention patent CN110203896A describes a method for preparing two-dimensional material nanosheets using ball milling-enhanced exfoliation. The sample (black phosphorus, graphene, molybdenum disulfide) is pre-ground in a solvent, then further ground in a ball mill for 2-72 hours, and finally ultrasonically treated to obtain two-dimensional material nanosheets. Chinese invention patent CN107200318A describes a method for preparing two-dimensional material quantum sheets, where raw materials (graphite, MoS2, hexagonal boron nitride, graphitic carbon nitride, black phosphorus) are first dry-milled in a ball mill for 0.5-120 hours, then the resulting product is ultrasonically treated in a solvent, and finally filtered to obtain two-dimensional material quantum sheets. While the ball milling followed by ultrasonication methods disclosed in the above patents have high yields and fewer defects, the preparation time is relatively long. Chinese invention patent CN107879332A describes a method for preparing graphene by exfoliating graphite using a spatiotemporal synchronous ultrasonic ball milling method. The method involves adding graphite raw materials and exfoliation reagents into an ultrasonic ball milling device and milling them under ultrasonic conditions for 2-96 hours. The mixture is then separated, washed, and dried to obtain graphene powder. It is evident that the preparation time is relatively long.

[0007] In summary, the preparation of two-dimensional silicon carbide still faces significant challenges. While liquid-phase ultrasonic exfoliation can successfully produce two-dimensional silicon carbide sheets, the yield and quality are low. Although ball milling offers high yields, its preparation time is too long. Therefore, there is a need in this field to develop a method for preparing two-dimensional silicon carbide sheets using ultrasonic ball milling, which can effectively solve the aforementioned problems. Summary of the Invention

[0008] The purpose of this invention is to provide a two-dimensional silicon carbide sheet and its ultrasonic ball milling preparation method. This method effectively transfers the energy of the grinding media to the material by combining ultrasound and ball milling, thereby improving the controllability and repeatability of the two-dimensional silicon carbide sheet preparation process, greatly improving the quality of the product and the grinding efficiency, and providing a feasible path for the large-scale preparation of two-dimensional silicon carbide sheets.

[0009] To achieve the above objectives, the present invention provides a method for preparing two-dimensional silicon carbide sheets by ultrasonic ball milling, comprising the following steps: Step S1: Take silicon carbide powder, grinding media and organic solvent, mix silicon carbide powder, grinding media and organic solvent, and simultaneously perform ultrasonic ball milling in a vacuum or inert gas environment to obtain the upper liquid. Step S2: Centrifuge the upper liquid to obtain a clear upper liquid containing two-dimensional silicon carbide; Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber for drying to obtain two-dimensional silicon carbide sheets.

[0010] Preferably, in step S1, the mass ratio of silicon carbide powder, grinding media, and organic solvent is 1:(600-700):(85-120).

[0011] Preferably, in step S1, the silicon carbide powder is one or more combinations of the crystal forms 2R, 2H, 3C, 4H, 6H, and 15R; The organic solvent is one or more combinations of methanol, isopropanol, N-methylpyrrolidone, ethanol, acetone, dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, sulfolane, tetrahydrofuran, acetonitrile, chloroform, ethylenediamine, deoxycyclohexane, anisole, carbon disulfide, and ethyl acetate.

[0012] Preferably, in step S1, the grinding media is one or more combinations of steel balls, ceramic balls, glass balls, agate balls, tungsten carbide balls, silicon nitride balls, alumina balls, and zirconium oxide balls; The size of the grinding media is a combination of 1mm, 3mm, 5mm and 10mm; when the grinding media is a combination of 1mm, 3mm and 5mm mixed and 10mm, the mass ratio between 1mm, 3mm and 5mm mixed and 10mm is 1:(4-5):(3-4), and the mass ratio between 3mm and 5mm in the 3mm and 5mm mixed is 1:2.

[0013] Preferably, in step S1, the ultrasonic ball milling speed is 200-300 rpm, the ultrasonic ball milling power is 750 W, the ultrasonic ball milling current is 0-0.8 A, the ultrasonic ball milling frequency is 40 kHz, and the ultrasonic ball milling time is 1-8 h.

[0014] Preferably, in step S1, the preparation of the vacuum or inert gas environment specifically involves evacuating the vacuum for 30 minutes with a pressure of 0.1-0.2 MPa; or evacuating the vacuum for 30 minutes and then filling it with inert gas with a pressure of 0.1-0.2 MPa. The inert gas is one or more combinations of helium, neon, argon, krypton, and xenon.

[0015] Preferably, in step S2, the centrifugation speed is 1000-10000 rpm, and high-speed centrifugation is used to remove unpeeled silicon carbide particles. The centrifugation time is 10-60 min.

[0016] Preferably, in step S3, the drying temperature is 0-300℃ and the drying time is 1-12h.

[0017] The present invention also provides a method for preparing two-dimensional silicon carbide sheets by ultrasonic ball milling.

[0018] The present invention employs the above-mentioned two-dimensional silicon carbide sheet and its ultrasonic ball milling preparation method, and the beneficial effects are as follows: (1) This invention employs real-time synergistic ultrasonic ball milling to prepare two-dimensional sheet-like silicon carbide from silicon carbide powder using organic solvents and ball milling media through liquid-phase exfoliation. Compared to ordinary ball milling, this invention adds an ultrasonic device, utilizing the synergistic effect of shear force and friction to achieve material planarization. In existing real-time synergistic ultrasonic ball milling technology, a step of evacuating the material tank and selectively filling it with inert gas is added, placing the material tank in a vacuum or inert gas state. This operation not only removes oxygen and forms a protective atmosphere, preventing material oxidation, but also ensures the purity and chemical properties of the material, greatly improving product quality. Simultaneously, it reduces energy loss, allowing the energy of the grinding media to be transferred to the material more effectively, improving ball milling efficiency and facilitating faster grinding of the material to the desired particle size.

[0019] (2) The entire preparation process in this invention is simple, which improves the controllability and repeatability of the two-dimensional silicon carbide sheet preparation process. This method successfully realizes the phase transition of silicon carbide from a wurtzite structure to a graphite-like structure, and can effectively obtain high-quality, large-size ultrathin two-dimensional silicon carbide nanosheet materials with a complete lattice structure.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a SEM image of 2R silicon carbide powder in Example 1 of the present invention, which describes a two-dimensional silicon carbide sheet and its ultrasonic ball milling preparation method. Figure 2 This is a SEM image of the two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 4.5 hours in Example 1 of the present invention, which is a two-dimensional silicon carbide sheet and its preparation method by ultrasonic ball milling. Figure 3 This is a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 8 hours in Example 1 of the present invention. Figure 4 This is a STEM image of the two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 4.5 hours in Example 1 of the present invention, which is a two-dimensional silicon carbide sheet and its preparation method by ultrasonic ball milling. Figure 5 The image shows the HRTEM image of the two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 4.5 h in Example 1 of the present invention, which is a two-dimensional silicon carbide sheet and its ultrasonic ball milling preparation method. In the image, A is the selected region, B is the magnified view of the selected region, C is the Fourier transform image of the selected region, and D is the inverse Fourier transform image of the selected region. Figure 6 This is an optical microscope image of the two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 4.5 hours in Example 1 of the present invention, which is a two-dimensional silicon carbide sheet and its preparation method by ultrasonic ball milling. Figure 7 The ultraviolet absorption spectra of the two-dimensional silicon carbide sheets prepared by ultrasonic ball milling for 1.5h-9h in Example 1 and Comparative Example 1 of the present invention are shown. Figure 8 This is a SEM image of the two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 4.5 hours in Example 2 of the present invention, which describes a two-dimensional silicon carbide sheet and its preparation method. Figure 9 This is a SEM image of the two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 4.5 hours in Example 2 of the present invention, which describes a two-dimensional silicon carbide sheet and its preparation method. Figure 10 This is a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling at a rotation speed of 200 rpm in Example 3 of the present invention. Figure 11 This is an SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling at a speed of 200 rpm in Example 3 of the present invention; wherein, A is the selected region, B is an enlarged view of the selected region, and C is the inverse Fourier transform image of the selected region. Figure 12 This is a confocal microscope image of a two-dimensional silicon carbide sheet prepared in Example 4 of the ultrasonic ball milling method of the present invention, where the mass ratio of 2R silicon carbide powder, grinding media, and isopropanol is 1:700:120. Figure 13 This is an atomic force microscope image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Example 4 of the present invention, where the mass ratio of 2R silicon carbide powder, grinding media, and isopropanol is 1:700:120. Figure 14 This is an SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Example 4 of the present invention, where the mass ratio of 2R silicon carbide powder, grinding media, and isopropanol is 1:700:120. Figure 15 This is a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Example 5 of the present invention, using zirconium oxide as the grinding ball medium. Figure 16The image shows a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 9 hours in Comparative Example 1, which is a method for preparing a two-dimensional silicon carbide sheet according to the present invention. Figure 17 The image shows a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling for 9 hours in Comparative Example 2, which is a method for preparing a two-dimensional silicon carbide sheet according to the present invention. Figure 18 This is a confocal Raman micrograph of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Comparative Example 3 at a rotation speed of 500 rpm. Figure 19 The image shows a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Comparative Example 3 at a rotation speed of 150 rpm. Figure 20 The TEM image shows the two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Comparative Example 4 using pure 3mm alumina balls, according to the present invention. Figure 21 The image shows a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Comparative Example 5 of the present invention, where the mass ratio of 2R silicon carbide powder, grinding media, and isopropanol is 1:150:40. Figure 22 An atomic force microscope image of the two-dimensional silicon carbide sheet prepared by the ultrasonic ball milling method of the present invention in Comparative Example 5 at a mass ratio of 1:300:90 between 2R silicon carbide powder, grinding media, and isopropanol. Figure 23 Comparative Example 5 illustrates a two-dimensional silicon carbide sheet and its ultrasonic ball milling preparation method according to the present invention. Figure 18 Thickness distribution diagram at the marked line; Figure 24 The image shows a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Comparative Example 5 of the present invention, where the mass ratio of 2R silicon carbide powder, grinding media, and isopropanol is 1:300:90. Figure 25 The image shows a SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Comparative Example 6, where the two-dimensional silicon carbide sheet was prepared by mixing three sizes (10 mm, 3 mm, and 5 mm) and 1 mm in a mass ratio of 6:3:1. Figure 26 This is an SEM image of a two-dimensional silicon carbide sheet prepared by ultrasonic ball milling in Comparative Example 7 using iron balls as the grinding media, according to the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0024] Example 1 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:650:85.

[0025] The grinding media consist of a mixture of alumina balls in four sizes: 1mm, 3mm, 5mm, and 10mm. The mass ratio of the 10mm, 3mm, and 5mm balls and the 1mm balls is 4:5:1, while the mass ratio of the 3mm and 5mm balls is 1:2.

[0026] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes to ensure that the material tank was always under vacuum, preventing the material from being oxidized and the isopropanol from evaporating during the ball milling process. The ultrasonic ball milling was carried out at a frequency of 40 kHz and a power of 750 W for 1-8 hours at a speed of 250 rpm. The supernatant was collected at 1.5 h, 3 h, 4.5 h, 6 h, and 8 h.

[0027] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0028] like Figure 1 As shown, silicon carbide appears as an irregular blocky solid.

[0029] like Figures 2-3 As shown, it can be clearly seen that silicon carbide changes from a block shape to a sheet shape and has a tendency to become transparent, and the size of silicon carbide is 10-15μm.

[0030] like Figures 4-5 As shown, the highly ordered crystal structure of the exfoliated silicon carbide nanosheets clearly exhibits a hexagonal graphene-like honeycomb structure, which also confirms that silicon carbide materials can be transformed from sp... 3 to sp 2 The transformation.

[0031] like Figure 6 As shown in the figure, the sheets are light blue and transparent, with a size of approximately 10-15 μm, which is consistent with the SEM results.

[0032] like Figure 7 As shown, the structure is rapidly destroyed in the initial stage of ball milling (1.5-3h), and the absorbance changes significantly; in the later stage (6-8h), the structure tends to stabilize, and the absorbance change gradually slows down. The absorbance change is relatively small after ball milling for 4.5h; therefore, 4.5h is selected as the optimal ball milling time for this material.

[0033] Example 2 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:650:85.

[0034] The grinding media consist of a mixture of alumina balls in four sizes: 1mm, 3mm, 5mm, and 10mm. The mass ratio of the 10mm, 3mm, and 5mm balls and the 1mm balls is 4:5:1, while the mass ratio of the 3mm and 5mm balls is 1:2.

[0035] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes and filled with argon gas to keep the material tank under argon gas conditions during the ball milling process, preventing the material from being oxidized and the isopropanol from volatilizing. The ultrasonic ball milling was carried out at a frequency of 40 kHz and a power of 750 W for 4.5 hours at a speed of 250 rpm, and the upper liquid was collected.

[0036] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0037] like Figures 8-9 As shown, the silicon carbide clearly changes from a block shape to a sheet shape and shows a tendency to become transparent, with the silicon carbide size ranging from 10 to 15 μm. Furthermore, compared to Example 1, the material container being in a vacuum or argon atmosphere produces the same effect, both yielding effective two-dimensional silicon carbide sheets.

[0038] Example 3 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:650:85.

[0039] The grinding media consist of a mixture of alumina balls in four sizes: 1mm, 3mm, 5mm, and 10mm. The mass ratio of the 10mm, 3mm, and 5mm balls and the 1mm balls is 4:5:1, while the mass ratio of the 3mm and 5mm balls is 1:2.

[0040] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes and filled with argon gas to keep the material tank under argon gas conditions during the ball milling process, preventing the material from being oxidized and the isopropanol from volatilizing. The ultrasonic ball milling was performed at a frequency of 40 kHz, a power of 750 W, and a speed of 200 rpm. The upper liquid was collected after 4.5 hours of ultrasonic ball milling.

[0041] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0042] like Figure 10 As shown, a large number of sheet-like products were found. Therefore, a reasonable ultrasonic ball milling speed of 200 rpm was used to prepare high-quality two-dimensional silicon carbide, which is consistent with the results of Examples 1 and 2.

[0043] like Figure 11 As shown, the inset in the figure is an enlarged view of the selected area and a diagram of the selected area after inverse Fourier transform. The figure directly reflects the periodicity of the hexagonal lattice, which is a typical feature of two-dimensional silicon carbide sheets.

[0044] Example 4 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:700:120.

[0045] The grinding media consist of a mixture of alumina balls in four sizes: 1mm, 3mm, 5mm, and 10mm. The mass ratio of the 10mm, 3mm, and 5mm balls and the 1mm balls is 4:5:1, while the mass ratio of the 3mm and 5mm balls is 1:2.

[0046] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes and filled with argon gas to keep the material tank under argon gas conditions during the ball milling process, preventing the material from being oxidized and the isopropanol from evaporating. The ultrasonic ball milling was performed at a frequency of 40 kHz, a power of 750 W, and a speed of 250 rpm. The upper liquid was collected after 4.5 hours of ultrasonic ball milling.

[0047] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0048] like Figure 12 As shown, the confocal microscope image of the two-dimensional silicon carbide prepared in Example 4 with a mass ratio of 2R silicon carbide powder, grinding media, and isopropanol of 1:700:120 (at which point the material fills two-thirds of the mill jar) is displayed. The values ​​in the image represent the height of the point, i.e., the thickness of the wafer at that point. It is clear that the minimum thickness of the obtained two-dimensional silicon carbide wafer is 2 nm. This demonstrates that with a mass ratio of 2R silicon carbide powder, grinding media, and isopropanol of 1:700:120, the material being fully covered by the grinding balls can yield a relatively thin two-dimensional silicon carbide wafer. This result is consistent with that of Example 1, proving that a satisfactory two-dimensional silicon carbide wafer can only be obtained when the material fills two-thirds of the mill jar.

[0049] like Figure 13 As shown, the atomic force microscopy image of the two-dimensional silicon carbide prepared in Example 4 with a mass ratio of 2R silicon carbide powder, grinding media, and isopropanol of 1:700:120 (at which point the material fills two-thirds of the ball mill jar) shows that the thickness of the resulting sheet is within 3.5 nm, which is consistent with the results of confocal microscopy.

[0050] like Figure 14 As shown, the SEM image of the two-dimensional silicon carbide prepared in Example 4 with a mass ratio of 2R silicon carbide powder, grinding media, and isopropanol of 1:700:120 (at which point the ball mill jar is filled to two-thirds capacity) is clearly shown. The red circles in the image are significantly different from those in the previous example. Figure 24 Thinner and nearly transparent, this indicates that the two-dimensional silicon carbide sheet becomes more transparent as its thickness decreases.

[0051] Example 5 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:700:120.

[0052] The grinding media consist of a mixture of zirconia balls and agate balls in four sizes: 1mm, 3mm, 5mm, and 10mm. The mass ratio of the 10mm, 3mm, and 5mm balls and the 1mm balls is 4:5:1, and the mass ratio of the 3mm and 5mm balls is 1:2.

[0053] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes and filled with argon gas to keep the material tank under argon gas conditions during the ball milling process, preventing the material from being oxidized and the isopropanol from evaporating. The ultrasonic ball milling was performed at a frequency of 40 kHz, a power of 750 W, and a speed of 250 rpm. The upper liquid was collected after 4.5 hours of ultrasonic ball milling.

[0054] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0055] like Figure 15 As shown, the SEM image of the two-dimensional silicon carbide sheet prepared by using zirconium oxide as the grinding ball medium in Example 5 shows that the effect is consistent with that of alumina balls (the effect of agate balls is also consistent with that of Example 1).

[0056] Comparative Example 1 A method for preparing two-dimensional silicon carbide sheets by ultrasonic ball milling. The difference between this comparative example and Example 1 is that in step S1, ultrasonic ball milling is performed for 9 hours, and the supernatant is taken after 9 hours. The remaining steps are the same as in Example 1.

[0057] like Figure 7 , Figure 16 As shown, it is evident from the SEM image of the two-dimensional silicon carbide prepared by ultrasonic ball milling for 9 hours that agglomeration occurs significantly. Furthermore, the curve in the UV absorption spectrum at 9 hours is almost identical to that at 6 hours, indicating that further extending the ball milling time has little effect on the particle size of the material. Therefore, an ultrasonic ball milling time of 1-8 hours is appropriate.

[0058] Comparative Example 2 A method for preparing two-dimensional silicon carbide sheets by ultrasonic ball milling. The difference between this comparative example and Example 2 is that in step S1, ultrasonic ball milling is performed for 9 hours, while the remaining steps are the same as in Example 2.

[0059] likeFigure 17 As shown in the figure, it is clear that the two-dimensional silicon carbide SEM image obtained by ultrasonic ball milling for 9 hours shows obvious agglomeration. Therefore, the ultrasonic ball milling time is appropriate between 1 and 8 hours.

[0060] Comparative Example 3 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets is disclosed. The difference between this comparative example and Example 3 is that in step S1, ball milling is performed at ball milling speeds of 150 rpm and 500 rpm, respectively. The remaining steps are the same as in Example 3.

[0061] like Figure 18 As shown, the confocal microscopy Raman image of the two-dimensional silicon carbide sheet prepared by ball milling at 500 rpm in Comparative Example 3 clearly shows the inherent Raman peak of silicon carbide at 790 cm⁻¹. -1 The disappearance of the peak and the appearance of a new one indicate that oxidation or interlayer disruption of the material at this point may have introduced new vibrational modes. Furthermore, at a rotation speed of 500 rpm, the product exhibits agglomeration, and excessively high rotation speeds can severely damage the crystal structure of two-dimensional silicon carbide.

[0062] like Figure 19 As shown in the figure, the SEM image of the two-dimensional silicon carbide sheet prepared by Comparative Example 3 at a ball milling speed of 150 rpm shows a large number of blocky objects, indicating that the collision energy between the grinding ball and the raw material is insufficient when the speed is too low, and the silicon carbide cannot be effectively peeled off.

[0063] Comparative Example 4 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:650:85.

[0064] The grinding media are pure 3mm alumina balls.

[0065] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes to ensure that the material tank was always under vacuum, preventing the material from being oxidized and the isopropanol from evaporating during the ball milling process. The ultrasonic ball milling was performed at a frequency of 40 kHz, a power of 750 W, and a speed of 250 rpm. The upper liquid was collected after 4.5 hours of ultrasonic ball milling.

[0066] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0067] like Figure 20 As shown, the inset in the figure is the electron diffraction pattern of the selected region, and... Figure 5 Compared to the hexagonal ring electron diffraction pattern, the electron diffraction pattern shows concentric rings as well as discrete diffraction spots, indicating that the obtained material has both polycrystalline and single-crystal regions coexisting, or that the material has impurities, which may lead to defects in the crystal structure and thus affect the performance of the two-dimensional material.

[0068] It is evident that materials obtained using a single-size grinding ball are smaller in size and have uneven thickness, indicating that smaller grinding balls have lower energy and are difficult to achieve high-quality peeling. Conversely, the use of larger grinding balls results in noticeable damage to the resulting flakes, suggesting that the ball milling collision energy is too high, causing damage to the two-dimensional material. Therefore, a comparison shows that using a mixture of 1mm, 3mm, 5mm, and 10mm alumina balls is the optimal grinding media size.

[0069] Comparative Example 5 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:150:40 and 1:300:90 respectively.

[0070] The grinding media consist of a mixture of alumina balls in four sizes: 1mm, 3mm, 5mm, and 10mm. The mass ratio of the 10mm, 3mm, and 5mm balls and the 1mm balls is 4:5:1, while the mass ratio of the 3mm and 5mm balls is 1:2.

[0071] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes and filled with argon gas to keep the material tank under argon gas conditions during the ball milling process, preventing the material from being oxidized and the isopropanol from evaporating. The ultrasonic ball milling was performed at a frequency of 40 kHz, a power of 750 W, and a speed of 250 rpm. The upper liquid was collected after 4.5 hours of ultrasonic ball milling.

[0072] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0073] like Figure 21As shown, when the mass ratio of 2R silicon carbide powder, grinding media, and isopropanol is 1:150:40, the material fills less than one-third of the ball mill jar, and most of the silicon carbide is not fully ground, with SEM showing that it is mostly in blocky form.

[0074] like Figures 22-23 As shown in the figure, the thickness of the sheet-like material obtained is within 40-60 nm, indicating that the material tank filling rate is small, resulting in low grinding efficiency.

[0075] like Figure 24 As shown, the SEM image of the two-dimensional silicon carbide obtained in Comparative Example 5 with a mass ratio of 1:300:90 between 2R silicon carbide powder, grinding media, and isopropanol (at which point the material fills less than two-thirds of the ball mill jar) shows a small number of flakes, but the thickness is relatively thick, about 20-30 nm.

[0076] Comparative Example 6 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:700:120.

[0077] The grinding media consist of a mixture of alumina balls in four sizes: 1mm, 3mm, 5mm, and 10mm. The mass ratio of the 10mm, 3mm, and 5mm balls and the 1mm balls is 6:3:1, and the mass ratio of the 3mm and 5mm balls is 1:2.

[0078] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes and filled with argon gas to keep the material tank under argon gas conditions during the ball milling process, preventing the material from being oxidized and the isopropanol from evaporating. The ultrasonic ball milling was performed at a frequency of 40 kHz, a power of 750 W, and a speed of 250 rpm. The upper liquid was collected after 4.5 hours of ultrasonic ball milling.

[0079] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0080] like Figure 25As shown in the figure, the silicon carbide material is clearly not sufficiently ground. Although the resulting product has a tendency to form flakes, its thickness is too great. This proves that the proportion of large spheres should not be too high, as this will cause the gaps to be too large for the spheres to fill effectively, resulting in insufficient grinding. The experiment revealed that an excessive proportion of small spheres causes the material to clump together due to poor tumbling, leading to insufficient grinding.

[0081] Comparative Example 7 An ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets includes the following steps: Step S1: Weigh out 2R silicon carbide powder, grinding media and isopropanol according to the mass ratio of 2R silicon carbide powder, grinding media and isopropanol of 1:650:85.

[0082] The grinding media consist of a mixture of iron balls and glass balls of four sizes: 1mm, 3mm, 5mm, and 10mm. The mass ratio of the 10mm, 3mm, and 5mm balls and the 1mm balls is 4:5:1, and the mass ratio of the 3mm and 5mm balls is 1:2.

[0083] 2R silicon carbide powder, grinding media, and isopropanol were added to an ultrasonic planetary ball mill for mixing. The material tank was evacuated for 30 minutes to ensure that the material tank was always under vacuum, preventing the material from being oxidized and the isopropanol from evaporating during the ball milling process. The ultrasonic ball milling was performed at a frequency of 40 kHz, a power of 750 W, and a speed of 250 rpm. The upper liquid was collected after 4.5 hours of ultrasonic ball milling.

[0084] Step S2: Centrifuge the obtained supernatant at 4000 rpm for 20 min to obtain a supernatant containing two-dimensional silicon carbide. Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber and dry it at 60°C for 12 hours to obtain two-dimensional silicon carbide sheets.

[0085] like Figure 26 As shown in the figure, a novel material significantly different from the sheet-like structure of Example 1 was discovered. The iron balls, with a lower hardness than alumina, are prone to shedding iron filings during ball milling, contaminating the sample. At high temperatures, they may also react chemically with the sample to form a new phase and alter the original material structure. Furthermore, the iron balls can scratch the liner during ball milling, reducing its lifespan.

[0086] When using glass balls for grinding, peeling fragments were found. Glass is brittle and has poor impact resistance, making it unsuitable for grinding silicon carbide.

[0087] Therefore, the present invention adopts the above-mentioned two-dimensional silicon carbide sheet and its ultrasonic ball milling preparation method. This method effectively transfers the energy of the grinding media to the material by combining ultrasound and ball milling, which improves the controllability and repeatability of the two-dimensional silicon carbide sheet preparation process, greatly improves the quality of the product and the grinding efficiency, and provides a feasible path for the large-scale preparation of two-dimensional silicon carbide sheets.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing two-dimensional silicon carbide sheets by ultrasonic ball milling, characterized in that, Includes the following steps: Step S1: Take silicon carbide powder, grinding media and organic solvent, mix silicon carbide powder, grinding media and organic solvent, and simultaneously perform ultrasonic ball milling in a vacuum or inert gas environment to obtain the upper liquid. Step S2: Centrifuge the upper liquid to obtain a clear upper liquid containing two-dimensional silicon carbide; Step S3: Place the upper clear liquid containing two-dimensional silicon carbide into a vacuum chamber for drying to obtain two-dimensional silicon carbide sheets.

2. The ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets according to claim 1, characterized in that: In step S1, the mass ratio of silicon carbide powder, grinding media, and organic solvent is 1:(600-700):(85-120).

3. The ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets according to claim 1, characterized in that: In step S1, the silicon carbide powder is one or more combinations of the crystal forms 2R, 2H, 3C, 4H, 6H, and 15R; The organic solvent is one or more combinations of methanol, isopropanol, N-methylpyrrolidone, ethanol, acetone, dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, sulfolane, tetrahydrofuran, acetonitrile, chloroform, ethylenediamine, deoxycyclohexane, anisole, carbon disulfide, and ethyl acetate.

4. The method for preparing two-dimensional silicon carbide sheets by ultrasonic ball milling according to claim 1, characterized in that: In step S1, the grinding media is one or more combinations of steel balls, ceramic balls, glass balls, agate balls, tungsten carbide balls, silicon nitride balls, alumina balls, and zirconium oxide balls; The size of the grinding media is a combination of 1mm, 3mm, 5mm and 10mm; when the grinding media is a combination of 1mm, 3mm and 5mm mixed and 10mm, the mass ratio between 1mm, 3mm and 5mm mixed and 10mm is 1:(4-5):(3-4), and the mass ratio between 3mm and 5mm in the 3mm and 5mm mixed is 1:

2.

5. The ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets according to claim 1, characterized in that: In step S1, the ultrasonic ball milling speed is 200-300 rpm, the ultrasonic ball milling power is 750W, the ultrasonic ball milling current is 0-0.8A, the ultrasonic ball milling frequency is 40KHz, and the ultrasonic ball milling time is 1-8h.

6. The ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets according to claim 1, characterized in that: In step S1, the preparation of the vacuum or inert gas environment specifically involves evacuating the vacuum for 30 minutes with a pressure of 0.1-0.2 MPa; or evacuating the vacuum for 30 minutes and then filling it with inert gas with a pressure of 0.1-0.2 MPa. The inert gas is one or more combinations of helium, neon, argon, krypton, and xenon.

7. The ultrasonic ball milling method for preparing two-dimensional silicon carbide sheets according to claim 1, characterized in that: In step S2, the centrifugation speed is 1000-10000 rpm and the centrifugation time is 10-60 min.

8. The method for preparing two-dimensional silicon carbide sheets by ultrasonic ball milling according to claim 1, characterized in that: In step S3, the drying temperature is 0-300℃ and the drying time is 1-12h.

9. A two-dimensional silicon carbide sheet prepared by an ultrasonic ball milling method according to any one of claims 1-8.

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