Method for preparing black phosphorus crystal through low-temperature melting transportation

Abstract

The invention relates to the technical field of semiconductor materials, in particular to a method for preparing black phosphorus crystals through low-temperature melting transportation, which comprises the following steps: firstly, mixing metal bismuth and iodine in proportion, putting the mixture into a reactor, and carrying out corresponding reaction through heat treatment to obtain a bismuth-iodine melting mixture with corresponding components; then, sealing red phosphorus and the molten mixture in a reactor in proportion, and carrying out corresponding reaction through heat treatment to obtain black phosphorus crystals. According to the method provided by the invention, the black phosphorus can be prepared at the lowest temperature of 270 DEG C through reasonable component proportion and heating, heat preservation and cooling procedures. The black phosphorus crystal prepared by the invention is high in purity and good in crystallinity, and the preparation process is mild in condition, simple in process, relatively low in equipment requirement and easy to implement, and has great market potential.

Description

Technical Field

[0001] The present application relates to the field of semiconductor material technology, and in particular to a method for preparing black phosphorus crystals by low-temperature melt transport. Background Art

[0002] As the most stable of the many allotropes of phosphorus, black phosphorus has shown a broad application space in related fields. Black phosphorus is a pure two-dimensional semiconductor material with a direct band gap. The band gap of black phosphorus can be changed according to its number of layers and thickness. The band gap of bulk black phosphorus is 0.3eV, while the band gap of monolayer black phosphorus is 2.0eV, so the band gap of black phosphorus has a very large variation space. The wide adjustable band gap enables black phosphorus to achieve wide-area light absorption, and its absorption range can range from the visible band to the infrared band. At the same time, its excellent carrier mobility and anisotropic characteristics make it begin to show its prowess in the current field of photoelectric detection.

[0003] Traditional methods for preparing black phosphorus include high temperature and high pressure method, chemical vapor transport method, ball milling method, chemical vapor deposition method, molten salt method, etc. Among them, the high temperature and high pressure method needs to be carried out at high temperature (1000℃) and high pressure (12000atm), which has high requirements for equipment, high energy consumption, and high cost of preparing black phosphorus; the chemical vapor transport method often also requires a higher temperature (above 600℃), and the energy consumption required for the reaction is high. In addition, the addition of a large amount of catalysts also greatly increases the preparation cost of black phosphorus; the black phosphorus prepared by the ball milling method has no requirements for temperature and pressure, but the preparation cycle is long and the synthesis rate is low; the chemical vapor deposition method is slow to synthesize and has high requirements for equipment. The traditional molten salt method requires white phosphorus to be dissolved in liquid bismuth metal. The entire preparation process is complicated. The participation of white phosphorus also greatly increases the risk factor of the reaction. In addition, the participation of a large amount of metal bismuth also leads to an increase in preparation costs. Waste liquid will also be generated during the preparation process, causing environmental pollution.

[0004] It can be seen that developing a method with simple preparation conditions, smooth process, low cost and efficient preparation of black phosphorus crystals is of great significance for promoting black phosphorus research and future industrial production. Summary of the invention

[0005] The embodiment of the present application provides a method for preparing black phosphorus crystals by low-temperature melt transport, which can achieve the preparation of black phosphorus at a minimum temperature of 270° C. through reasonable component ratios and heating, insulation and cooling procedures. The black phosphorus crystals prepared by the present invention have high purity and good crystallinity, and the conditions in the preparation process are mild, the process is simple, the equipment requirements are relatively low, and it is easy to implement, which has a very large market potential.

[0006] In order to solve the above technical problems, an embodiment of the present application provides a method for preparing black phosphorus crystals by low-temperature melt transport, comprising the following steps: step 1, mixing metallic bismuth and iodine in proportion and placing them in a reactor, and performing corresponding reactions through heat treatment to obtain a bismuth-iodine molten mixture of corresponding components; step 2, sealing red phosphorus and the molten mixture in a reactor in proportion, and performing corresponding reactions through heat treatment to obtain black phosphorus crystals.

[0007] In some exemplary embodiments, in step 1, when metallic bismuth and iodine are mixed in proportion, the molar ratio of metallic bismuth to iodine is (5-15):(5-30).

[0008] In some exemplary embodiments, in step 1, a reactor containing a mixture of metallic bismuth and iodine is placed in a muffle furnace and heated to perform a corresponding reaction.

[0009] In some exemplary embodiments, in step one, when the reactor is placed in a muffle furnace for heat treatment, it is heated from room temperature to 270°C to 350°C, the heating time is 60min to 240min, the insulation time is 120min to 1440min, and then cooled to room temperature, and the cooling time is 100min to 500min.

[0010] In some exemplary embodiments, the heating time is 90 min to 180 min, and the cooling time is 180 min to 300 min.

[0011] In some exemplary embodiments, in step 2, when the reactor is placed in a muffle furnace for heat treatment, it is heated from room temperature to 240°C to 350°C, the heating time is 30min to 240min, the insulation time is 120min to 6000min, and then cooled to room temperature, and the cooling time is 50min to 300min.

[0012] In some exemplary embodiments, the heating time is 60 min to 120 min, and the cooling time is 90 min to 240 min.

[0013] In some exemplary embodiments, the reactor is a vacuum sealed reactor.

[0014] In some exemplary embodiments, the material of the reactor includes one of stainless steel, boron nitride, aluminum oxide, silicon carbide, silicon nitride, or quartz.

[0015] In some exemplary embodiments, the material state of the metal bismuth includes powder or granules; the material state of the iodine includes granules, blocks or powder; and the material state of the red phosphorus includes powder or granules.

[0016] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0017] The embodiment of the present application provides a method for preparing black phosphorus crystals by low-temperature melt transport, comprising the following steps: step 1, mixing metallic bismuth and iodine in proportion and placing them in a reactor, performing corresponding reactions through heat treatment, and obtaining a bismuth-iodine molten mixture of corresponding components; step 2, sealing red phosphorus and the molten mixture in a reactor in proportion, performing corresponding reactions through heat treatment, and obtaining black phosphorus crystals.

[0018] The method for preparing black phosphorus crystals by low-temperature melt transport provided in the embodiment of the present application first uses bismuth and iodine as raw materials to prepare a Bi-BiI3 molten mixture of a specific ratio under vacuum conditions by setting a specific heat treatment program, and then mixes it with red phosphorus, and finally obtains black phosphorus crystals by setting a specific heat treatment program under vacuum conditions. The reaction temperature of the method is low, which can effectively reduce energy consumption. At the same time, compared with other preparation schemes, this method has low requirements for related equipment, thereby reducing the overall preparation difficulty and preparation cost.

[0019] In the method of the present application, by using Bi-I system molten salt, mineralizers and transport agents are no longer used, saving a large amount of non-phosphorus raw materials. In addition, in the method of the present invention, the Bi-I molten salt can be recycled after preparation. In addition, only the addition of red phosphorus is required in the subsequent preparation process, and the preparation of black phosphorus crystals at a minimum of 270°C can be achieved, so that the preparation cost of black phosphorus is further reduced. The method of the present invention uses a molten salt method to eliminate the safety hazards caused by the volatilization of phosphorus into steam, and the process route is simple and clear, with the potential for large-scale industrial preparation, thereby promoting the application and development of black phosphorus. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplifications do not constitute limitations on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute proportional limitations.

[0021] Figure 1 A schematic diagram of the preparation process of a method for preparing black phosphorus crystals by low-temperature melt transport provided in an embodiment of the present application.

[0022] Figure 2 This is a physical picture of the black phosphorus crystals prepared in Example 1 of the present application.

[0023] Figure 3 This is the X-ray diffraction pattern of the black phosphorus crystals prepared in Example 1 of the present application.

[0024] Figure 4 This is a Raman spectrum of the black phosphorus crystal prepared in Example 1 of the present application.

[0025] Figure 5 This is a high-resolution transmission electron microscopy image of the black phosphorus crystals prepared in Example 1 of the present application.

[0026] Figure 6 This is the X-ray photoelectron spectrum of the black phosphorus crystal prepared in Example 1 of the present application.

[0027] Figure 7 This is a physical picture of the black phosphorus crystals prepared in Example 2 of the present application.

[0028] Figure 8 This is a physical picture of the black phosphorus crystals prepared in Example 3 of the present application.

[0029] Fig. 9 This is a physical picture of the black phosphorus crystals prepared in Example 4 of the present application. DETAILED DESCRIPTION

[0030] From the background technology, it can be seen that the current traditional black phosphorus preparation method has high requirements for equipment, high energy consumption, high preparation cost of black phosphorus, long preparation cycle, low synthesis rate and other problems. In addition, the participation of a large amount of metallic bismuth also leads to an increase in preparation cost, and waste liquid is also generated during the preparation process, causing environmental pollution.

[0031] In order to solve the above technical problems, the embodiment of the present application provides a method for preparing black phosphorus crystals by low-temperature melt transport, comprising the following steps: first, metallic bismuth and iodine are mixed in proportion and placed in a reactor, and a corresponding reaction is carried out by heat treatment to obtain a bismuth-iodine molten mixture of corresponding components. Then, red phosphorus and the molten mixture are sealed in a reactor in proportion, and a corresponding reaction is carried out by heat treatment to obtain black phosphorus crystals. The embodiment of the present application provides a method for preparing black phosphorus crystals by low-temperature melt transport, which utilizes a molten salt method to achieve low-temperature preparation of black phosphorus crystals, with a mild overall reaction, low reaction conditions, and low cost.

[0032] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.

[0033] See also Figure 1 The present invention provides a method for preparing black phosphorus crystals by low-temperature melt transport, comprising the following steps:

[0034] Step S1, mixing metallic bismuth and iodine in proportion and placing them in a reactor, and performing corresponding reactions through heat treatment to obtain a bismuth-iodine molten mixture of corresponding components.

[0035] Step S2: sealing the red phosphorus and the molten mixture in a reactor in proportion, and performing corresponding reactions through heat treatment to obtain black phosphorus crystals.

[0036] The present application can realize the preparation of black phosphorus at a minimum temperature of 270° C. through reasonable component ratios and heating, heat preservation and cooling procedures. The black phosphorus crystals prepared by the present invention have high purity and good crystallinity, and the preparation process has mild conditions, simple process, relatively low requirements on equipment, easy to implement, and has very large market potential.

[0037] In some embodiments, in step S1, when metallic bismuth and iodine are mixed in proportion, the molar ratio of metallic bismuth to iodine is (5-15):(5-30). Preferably, the molar ratio of metallic bismuth to iodine is 5:6 or 10:12.

[0038] In some embodiments, in step S1, a reactor containing a mixture of metallic bismuth and iodine is placed in a muffle furnace and heated to perform a corresponding reaction.

[0039] In some embodiments, in step S1, when the reactor is placed in a muffle furnace for heat treatment, it is heated from room temperature to 270°C to 350°C, the heating time is 60min to 240min, the holding time is 120min to 1440min, and then cooled to room temperature, the cooling time is 100min to 500min. Preferably, the heating time is 90min to 180min, and the cooling time is 180min to 300min.

[0040] In some embodiments, in step S2, when the reactor is placed in a muffle furnace for heat treatment, it is heated from room temperature to 240°C to 350°C, the heating time is 30min to 240min, the heat preservation time is 120min to 6000min, and then cooled to room temperature, the cooling time is 50min to 300min. Preferably, the heating time is 60min to 120min, and the cooling time is 90min to 240min.

[0041] In some embodiments, the reactor is a vacuum sealed reactor; the material of the reactor includes one of stainless steel, boron nitride, aluminum oxide, silicon carbide, silicon nitride or quartz.

[0042] In some embodiments, the physical state of the metallic bismuth includes powder or granules; the physical state of the iodine includes granules, blocks or powder; and the physical state of the red phosphorus includes powder or granules.

[0043] The method for preparing black phosphorus crystals by low-temperature melt transport provided in the present application is described in detail below through specific examples.

[0044] Example 1

[0045] The method for preparing high-purity black phosphorus crystals in this embodiment comprises the following steps:

[0046] Bismuth particles and iodine particles are mixed in a molar ratio of 5:9, loaded into a new quartz tube with an inner diameter of 18 mm, and vacuum sealed. It is placed in a muffle furnace, heated to 300°C at 5°C / min, kept warm for 1080 minutes, and naturally cooled to room temperature to obtain a molten mixture of a specific component Bi-BiI3. The molten mixture is then mixed with red phosphorus powder in a mass ratio of 5:1, loaded into a new quartz tube with an inner diameter of 18 mm, and vacuum sealed. It is placed in a muffle furnace, heated to 350°C at 5°C / min, kept warm for 1080 minutes, and naturally cooled to room temperature. Obvious black phosphorus crystal clusters can be seen on the wall of the quartz tube, as shown in the figure. Figure 1 shown.

[0047] Figure 2 The black phosphorus X-ray diffraction pattern obtained in Example 1 of the present application has no extra impurity peaks compared with the standard PDF card, and the characteristic peaks at the orientations (020), (021), (040), and (060) are very strong and sharp, indicating that the material is an orthogonal black phosphorus crystal material with very high cleanliness.

[0048] Figure 3 The Raman spectrum of black phosphorus obtained in Example 1 of the present application highlights that the black phosphorus crystals prepared in this example have obvious and sharp characteristic peaks and no other impurity peaks, proving that they have high crystal quality.

[0049] Figure 4 The transmission electron microscope image of black phosphorus prepared in Example 1 of the present application shows clear lattice fringes, demonstrating that the black phosphorus crystals prepared in this example have high crystallinity and excellent crystal quality.

[0050] Figure 5 This is the black phosphorus X-ray photoelectron spectrum obtained in Example 1 of the present application. The spectrum can reflect that the black phosphorus crystals prepared in this example are of high purity and good quality.

[0051] Example 2

[0052] The method for preparing high-purity black phosphorus crystals in this embodiment comprises the following steps:

[0053] Bismuth particles and iodine particles are mixed in a molar ratio of 2:3, loaded into a new quartz tube with an inner diameter of 18 mm, and vacuum sealed. It is placed in a muffle furnace, heated to 280°C at 5°C / min, kept warm for 1080 minutes, and naturally cooled to room temperature to obtain a molten mixture of a specific component Bi-BiI3. The molten mixture is then mixed with red phosphorus powder in a mass ratio of 5:1, loaded into a new quartz tube with an inner diameter of 18 mm, and vacuum sealed. It is placed in a muffle furnace, heated to 270°C at 5°C / min, kept warm for 1800 minutes, and naturally cooled to room temperature. Obvious black phosphorus crystal clusters can be seen on the wall of the quartz tube, as shown in the figure. Figure 6 shown.

[0054] Example 3

[0055] The method for preparing high-purity black phosphorus crystals in this embodiment comprises the following steps:

[0056] Bismuth particles and iodine particles are mixed in a molar ratio of 5:6, loaded into a new quartz tube with an inner diameter of 18 mm, and vacuum sealed. It is placed in a muffle furnace, heated to 290°C at 5°C / min, kept warm for 1080 minutes, and naturally cooled to room temperature to obtain a molten mixture of a specific component Bi-BiI3. The molten mixture is then mixed with red phosphorus powder in a mass ratio of 5:1, loaded into a new quartz tube with an inner diameter of 18 mm, and vacuum sealed. It is placed in a muffle furnace, heated to 300°C at 5°C / min, kept warm for 1500 minutes, and naturally cooled to room temperature. Obvious black phosphorus crystal clusters can be seen on the wall of the quartz tube, as shown in the figure. Figure 7 shown.

[0057] Example 4

[0058] The method for preparing high-purity black phosphorus crystals in this embodiment comprises the following steps:

[0059] Bismuth particles and iodine particles are mixed in a molar ratio of 1:1, loaded into a new quartz tube with an inner diameter of 18 mm, and vacuum sealed. It is placed in a muffle furnace, heated to 320°C at 5°C / min, kept warm for 1080 minutes, and naturally cooled to room temperature to obtain a molten mixture of a specific component Bi-BiI3. The molten mixture is then mixed with red phosphorus powder in a mass ratio of 5:1, loaded into a new quartz tube with an inner diameter of 18 mm, and vacuum sealed. It is placed in a muffle furnace, heated to 330°C at 5°C / min, kept warm for 1200 minutes, and naturally cooled to room temperature. Obvious black phosphorus crystal clusters can be seen on the wall of the quartz tube, as shown in the figure. Figure 8 shown.

[0060] Comparative Example 1

[0061] Bismuth powder and red phosphorus powder were mixed in a mass ratio of 5:4, loaded into a new quartz tube with an inner diameter of 18 mm, and sealed by vacuum. The tube was placed in a muffle furnace, heated to 300°C at 5°C / min, kept warm for 1500 minutes, and cooled naturally to room temperature. No obvious black phosphorus crystal clusters were generated on the wall of the quartz tube.

[0062] Comparative Example 2

[0063] The method for preparing high-purity black phosphorus crystals in this embodiment comprises the following steps:

[0064] Bismuth particles and iodine particles are mixed in a molar ratio of 1:3, loaded into a new quartz tube with an inner diameter of 18mm, and vacuum sealed. It is placed in a muffle furnace, heated to 300℃ at 5℃ / min, kept warm for 1080min, and naturally cooled to room temperature to obtain a specific component product. The product is then mixed with red phosphorus powder in a mass ratio of 5:1, loaded into a new quartz tube with an inner diameter of 18mm, and vacuum sealed. It is placed in a muffle furnace, heated to 300℃ at 5℃ / min, kept warm for 1500min, and naturally cooled to room temperature. There are no obvious black phosphorus crystal clusters on the quartz tube wall.

[0065] In summary, the strategy of preparing black phosphorus crystals by the molten salt method adopted in the present invention can prepare black phosphorus crystals, and the preparation temperature is greatly reduced, which can relatively reduce energy consumption. The prepared black phosphorus crystals are of superior quality and high cleanliness. The conditions in the preparation process are mild, the process is simple, the equipment requirements are relatively low, and it is easy to implement.

[0066] The embodiment of the present application provides a method for preparing black phosphorus crystals by low-temperature melt transport, comprising the following steps: step 1, mixing metallic bismuth and iodine in proportion and placing them in a reactor, performing corresponding reactions through heat treatment, and obtaining a bismuth-iodine molten mixture of corresponding components; step 2, sealing red phosphorus and the molten mixture in a reactor in proportion, performing corresponding reactions through heat treatment, and obtaining black phosphorus crystals.

[0067] The method for preparing black phosphorus crystals by low-temperature melt transport provided in the embodiment of the present application first uses bismuth and iodine as raw materials to prepare a Bi-BiI3 molten mixture of a specific ratio under vacuum conditions by setting a specific heat treatment program, and then mixes it with red phosphorus, and finally obtains black phosphorus crystals by setting a specific heat treatment program under vacuum conditions. The reaction temperature of the method is low, which can effectively reduce energy consumption. At the same time, compared with other preparation schemes, this method has low requirements for related equipment, thereby reducing the overall preparation difficulty and preparation cost.

[0068] In the method of the present application, by using Bi-I system molten salt, mineralizers and transport agents are no longer used, saving a large amount of non-phosphorus raw materials. In addition, in the method of the present invention, the Bi-I molten salt can be recycled after preparation. In addition, only the addition of red phosphorus is required in the subsequent preparation process, and the preparation of black phosphorus crystals at a minimum of 270°C can be achieved, so that the preparation cost of black phosphorus is further reduced. The method of the present invention uses a molten salt method to eliminate the safety hazards caused by the volatilization of phosphorus into steam, and the process route is simple and clear, with the potential for large-scale industrial preparation, thereby promoting the application and development of black phosphorus.

[0069] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art can make their own changes and modifications without departing from the spirit and scope of the present application, so the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A method for preparing black phosphorus crystals by low-temperature melt transport, characterized in that: The following steps are involved: Step 1: Mixing metallic bismuth and iodine in proportion and placing them in a reactor, and performing corresponding reactions through heat treatment to obtain a bismuth-iodine molten mixture of corresponding components; Step 2: seal the red phosphorus and the molten mixture in a reactor in proportion, perform corresponding reactions through heat treatment, and obtain black phosphorus crystals.

2. The method for preparing black phosphorus crystals by low-temperature melt transport according to claim 1, characterized in that: In step 1, when metallic bismuth and iodine are mixed in proportion, the molar ratio of metallic bismuth to iodine is (5-15):(5-30).

3. The method for preparing black phosphorus crystals by low temperature melt transport according to claim 1, characterized in that: In step 1, a reactor containing a mixture of metallic bismuth and iodine is placed in a muffle furnace and heated to perform a corresponding reaction.

4. The method for preparing black phosphorus crystals by low temperature melting and transportation according to claim 3, characterized in that: In step one, the reactor is placed in a muffle furnace for heat treatment, heated from room temperature to 270°C to 350°C, the heating time is 60min to 240min, the insulation time is 120min to 1440min, and then cooled to room temperature, the cooling time is 100min to 500min.

5. The method for preparing black phosphorus crystals by low temperature melt transport according to claim 4, characterized in that: The heating time is 90min to 180min, and the cooling time is 180min to 300min.

6. The method for preparing black phosphorus crystals by low temperature melt transport according to claim 1, characterized in that: In step 2, the reactor is placed in a muffle furnace for heat treatment, heated from room temperature to 240°C to 350°C, the heating time is 30min to 240min, the insulation time is 120min to 6000min, and then cooled to room temperature, the cooling time is 50min to 300min.

7. The method for preparing black phosphorus crystals by low temperature melting and transportation according to claim 6, characterized in that: The heating time is 60min to 120min, and the cooling time is 90min to 240min.

8. The method for preparing black phosphorus crystals by low temperature melt transport according to claim 1, characterized in that: The reactor is a vacuum sealed reactor.

9. The method for preparing black phosphorus crystals by low temperature melt transport according to claim 1, characterized in that: The material of the reactor includes one of stainless steel, boron nitride, aluminum oxide, silicon carbide, silicon nitride or quartz.

10. The method for preparing black phosphorus crystals by low temperature melt transport according to claim 1, characterized in that: The material state of the metal bismuth includes powder or granular; the material state of the iodine includes granular, block or powder; the material state of the red phosphorus includes powder or granular.

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