A method for preparing black phosphorus crystal by low-temperature melt transportation

Abstract

The application relates to the technical field of semiconductor materials, in particular to a method for preparing black phosphorus crystals by low-temperature melting and transporting, which comprises the following steps: firstly, mixing metal bismuth and iodine according to a proportion and placing the mixture in a reactor, carrying out corresponding reactions through heat treatment to obtain a bismuth-iodine melting mixture with corresponding components; and then, sealing red phosphorus and the melting mixture in the reactor according to a proportion, carrying out corresponding reactions through heat treatment to obtain black phosphorus crystals. According to the method, black phosphorus can be prepared at a minimum temperature of 270 DEG C through reasonable component proportioning and temperature rising, temperature keeping and temperature lowering procedures. The black phosphorus crystals prepared by the method have high purity and good crystallinity, the preparation process is mild, the process is simple, the relative requirement for equipment is low, the method is easy to realize, and the method has great market potential.

Description

Technical Field

[0001] This application relates to the field of semiconductor materials technology, and in particular to a method for preparing black phosphorus crystals by low-temperature melting and transport. Background Technology

[0002] Black phosphorus, as one of the most stable allotropes of phosphorus, has shown broad application potential 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 varied depending on the number of layers and its thickness. Bulk black phosphorus has a band gap of 0.3 eV, while monolayer black phosphorus has a band gap of 2.0 eV, thus exhibiting a very large variability in its band gap. This wide, tunable band gap allows black phosphorus to achieve broad-area light absorption, ranging from the visible to the infrared band. Simultaneously, its excellent carrier mobility and anisotropic characteristics have made it a promising candidate in the current field of photoelectric detection.

[0003] Traditional methods for preparing black phosphorus include the high-temperature, high-pressure (HTHP) method, chemical vapor transport (CVT) method, ball milling method, chemical vapor deposition (CVD) method, and molten salt method. The HTHP method requires high temperatures (1000℃) and high pressures (12000 atm), placing high demands on equipment, consuming a lot of energy, and resulting in high production costs. The CVT method also often requires high temperatures (above 600℃), consuming a lot of energy, and the addition of large amounts of catalysts significantly increases the production cost. Ball milling does not have strict temperature and pressure requirements, but the preparation cycle is long and the synthesis rate is low. CVD is slow and requires sophisticated equipment. The traditional molten salt method requires dissolving white phosphorus in liquid bismuth metal, making the entire process complex. The presence of white phosphorus greatly increases the risk of the reaction, and the large amount of bismuth metal also increases the production cost. Furthermore, the process generates waste liquid that pollutes the environment.

[0004] Therefore, developing a method for preparing black phosphorus crystals that is simple, stable, low-cost, and efficient is of great significance for advancing black phosphorus research and future industrial production. Summary of the Invention

[0005] This application provides a method for preparing black phosphorus crystals using low-temperature melt transport. Through a reasonable component ratio and specific heating, holding, and cooling procedures, black phosphorus can be prepared at a minimum temperature of 270°C. The black phosphorus crystals prepared by this invention have high purity and good crystallinity. Furthermore, the preparation process is mild, simple, and requires relatively low-level equipment, making it easy to implement and possessing significant market potential.

[0006] To address the aforementioned technical problems, this application provides a method for preparing black phosphorus crystals via low-temperature melt transport, comprising the following steps: Step 1: Mixing metallic bismuth and iodine in a proportion and placing them in a reactor, then performing a corresponding reaction through heat treatment to obtain a bismuth-iodine molten mixture of the corresponding components; Step 2: Sealing red phosphorus and the molten mixture in a proportion within a reactor, then performing a corresponding reaction through heat treatment to obtain black phosphorus crystals.

[0007] In some exemplary embodiments, in step one, when metallic bismuth and iodine are mixed in a proportion of (5-15):(5-30).

[0008] In some exemplary embodiments, in step one, a reactor containing a mixture of metallic bismuth and iodine is placed in a muffle furnace and heated to carry out the 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 for 60 min to 240 min, held for 120 min to 1440 min, and then cooled to room temperature for 100 min to 500 min.

[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 two, when the reactor is placed in a muffle furnace for heat treatment, it is heated from room temperature to 240°C to 350°C for 30 min to 240 min, held for 120 min to 6000 min, and then cooled to room temperature for 50 min to 300 min.

[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 reactor is made of one of stainless steel, boron nitride, alumina, silicon carbide, silicon nitride, or quartz.

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

[0016] The technical solution provided in this application has at least the following advantages:

[0017] This 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 a certain proportion and placing them in a reactor, and carrying out the corresponding reaction through heat treatment to obtain a bismuth-iodine molten mixture of the corresponding components; Step 2, sealing red phosphorus and the molten mixture in a certain proportion in a reactor, and carrying out the corresponding reaction through heat treatment to obtain black phosphorus crystals.

[0018] The method for preparing black phosphorus crystals using low-temperature melt transport provided in this application first prepares a Bi-BiI3 molten mixture in a specific ratio using bismuth and iodine as raw materials under vacuum conditions through a specific heat treatment program. This mixture is then mixed with red phosphorus, and under vacuum conditions, a specific heat treatment program is followed to finally obtain black phosphorus crystals. The method features a low reaction temperature, effectively reducing energy consumption. Furthermore, compared to other preparation methods, this method has lower requirements for related equipment, thereby reducing the overall preparation difficulty and cost.

[0019] In this application, the method utilizes a Bi-I molten salt system, eliminating the need for mineralizing agents and transporting agents, thus saving a significant amount of non-phosphorus raw materials. Furthermore, the Bi-I molten salt prepared in this invention can be recycled. Additionally, only red phosphorus needs to be added in subsequent preparation processes, achieving black phosphorus crystal preparation at a minimum temperature of 270°C, further reducing the production cost of black phosphorus. The method of this invention, employing a molten salt method, eliminates the safety hazards caused by phosphorus volatilization, and its simple and clear process route has the potential for large-scale industrial production, thereby promoting the application and development of black phosphorus. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0021] Figure 1 This is a schematic diagram of the preparation process of a method for preparing black phosphorus crystals by low-temperature melting and transport, provided in an embodiment of this application.

[0022] Figure 2 This is a photograph of the black phosphorus crystals prepared in Example 1 of this application.

[0023] Figure 3 The image shows the X-ray diffraction pattern of the black phosphorus crystals prepared in Example 1 of this application.

[0024] Figure 4 The image shows the Raman spectrum of the black phosphorus crystal prepared in Example 1 of this application.

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

[0026] Figure 6 The image shows the X-ray photoelectron spectrum of the black phosphorus crystal prepared in Example 1 of this application.

[0027] Figure 7 This is a photograph of the black phosphorus crystals prepared in Example 2 of this application.

[0028] Figure 8 This is a photograph of the black phosphorus crystals prepared in Example 3 of this application.

[0029] Figure 9 This is a photograph of the black phosphorus crystals prepared in Example 4 of this application. Detailed Implementation

[0030] As can be seen from the background technology, the current traditional methods for preparing black phosphorus have problems such as high requirements for equipment, high energy consumption, high preparation cost, long preparation cycle, and low synthesis rate. In addition, the participation of a large amount of metallic bismuth also leads to an increase in preparation cost, and waste liquid is generated during the preparation process, causing pollution to the environment.

[0031] To address the aforementioned technical problems, this application provides a method for preparing black phosphorus crystals using low-temperature melt transport, comprising the following steps: First, metallic bismuth and iodine are mixed in a specific ratio and placed in a reactor, where a corresponding reaction is carried out through heat treatment to obtain a bismuth-iodine molten mixture of the corresponding components. Then, red phosphorus and the molten mixture are sealed in the reactor in a specific ratio, and a corresponding reaction is carried out through heat treatment to obtain black phosphorus crystals. This application provides a method for preparing black phosphorus crystals using low-temperature melt transport. This method utilizes the molten salt method to achieve low-temperature preparation of black phosphorus crystals, resulting in a mild overall reaction, low reaction conditions, and low cost.

[0032] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

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

[0034] Step S1: Mix metallic bismuth and iodine in a certain proportion and place them in a reactor. Then, carry out the corresponding reaction through heat treatment to obtain a molten bismuth-iodine mixture of the corresponding components.

[0035] Step S2: Seal the red phosphorus and molten mixture in a reactor in a certain proportion, and carry out the corresponding reaction through heat treatment to obtain black phosphorus crystals.

[0036] This application achieves the preparation of black phosphorus at a minimum temperature of 270℃ through reasonable component ratios and heating, holding, and cooling procedures. The black phosphorus crystals prepared by this invention have high purity and good crystallinity. Furthermore, the preparation process is mild, simple, and requires relatively low-end equipment, making it easy to implement and possessing significant market potential.

[0037] In some embodiments, when bismuth and iodine are mixed in step S1, the molar ratio of bismuth to iodine is (5-15):(5-30). Preferably, the molar ratio of 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 carry out the corresponding reaction.

[0039] In some embodiments, during 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 for 60 min to 240 min, held at that temperature for 120 min to 1440 min, and then cooled to room temperature for 100 min to 500 min. Preferably, the heating time is 90 min to 180 min, and the cooling time is 180 min to 300 min.

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

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

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

[0043] The method for preparing black phosphorus crystals by low-temperature melting and transport provided in this application will be described in detail below through specific embodiments.

[0044] Example 1

[0045] The preparation method of high-purity black phosphorus crystals in this embodiment includes the following steps:

[0046] Bismuth and iodine particles were mixed at a molar ratio of 5:9 and placed into a brand-new quartz tube with an inner diameter of 18 mm. The mixture was then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 300°C at a rate of 5°C / min, held for 1080 min, and then naturally cooled to room temperature to obtain a Bi-BiI3 molten mixture with a specific composition. This molten mixture was then mixed with red phosphorus powder at a mass ratio of 5:1 and placed into a brand-new quartz tube with an inner diameter of 18 mm. The mixture was then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 350°C at a rate of 5°C / min, held for 1080 min, and then naturally cooled to room temperature. Obvious clusters of black phosphorus crystals were visible on the wall of the quartz tube. Figure 1 As shown.

[0047] Figure 2 The X-ray diffraction pattern of black phosphorus obtained in Example 1 of this application, compared with the standard PDF card, shows no extra impurity peaks, and the characteristic peaks at the orientations (020), (021), (040), and (060) have very high intensity and sharp peak shape, indicating that the material is a highly clean orthogonal black phosphorus crystal material.

[0048] Figure 3 The image shows the Raman spectrum of black phosphorus prepared in Example 1 of this application. It highlights that the black phosphorus crystal prepared in this example has obvious and sharp characteristic peaks and no other impurity peaks, proving that it has high crystal quality.

[0049] Figure 4 The image shown is a transmission electron microscope (TEM) image of black phosphorus prepared in Example 1 of this application. Clear lattice fringes can be seen, demonstrating that the black phosphorus crystals prepared in this example have high crystallinity and excellent crystal quality.

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

[0051] Example 2

[0052] The preparation method of high-purity black phosphorus crystals in this embodiment includes the following steps:

[0053] Bismuth and iodine particles were mixed at a molar ratio of 2:3 and placed into a brand-new quartz tube with an inner diameter of 18 mm. The mixture was then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 280°C at a rate of 5°C / min, held for 1080 min, and then naturally cooled to room temperature to obtain a Bi-BiI3 molten mixture with a specific composition. This molten mixture was then mixed with red phosphorus powder at a mass ratio of 5:1 and placed into a brand-new quartz tube with an inner diameter of 18 mm. The mixture was then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 270°C at a rate of 5°C / min, held for 1800 min, and then naturally cooled to room temperature. Obvious clusters of black phosphorus crystals were visible on the wall of the quartz tube. Figure 6 As shown.

[0054] Example 3

[0055] The preparation method of high-purity black phosphorus crystals in this embodiment includes the following steps:

[0056] Bismuth and iodine particles were mixed in a molar ratio of 5:6 and placed into a brand-new quartz tube with an inner diameter of 18 mm. The mixture was then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 290 °C at a rate of 5 °C / min, held for 1080 min, and then naturally cooled to room temperature to obtain a Bi-BiI3 molten mixture with a specific composition. This molten mixture was then mixed with red phosphorus powder in a mass ratio of 5:1 and placed into a brand-new quartz tube with an inner diameter of 18 mm. The mixture was then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 300 °C at a rate of 5 °C / min, held for 1500 min, and then naturally cooled to room temperature. Obvious clusters of black phosphorus crystals were visible on the wall of the quartz tube. Figure 7 As shown.

[0057] Example 4

[0058] The preparation method of high-purity black phosphorus crystals in this embodiment includes the following steps:

[0059] Bismuth and iodine particles were mixed in a 1:1 molar ratio and placed into a brand-new quartz tube with an inner diameter of 18 mm. The mixture was then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 320°C at a rate of 5°C / min, held for 1080 min, and then naturally cooled to room temperature to obtain a Bi-BiI3 molten mixture with a specific composition. This molten mixture was then mixed with red phosphorus powder in a 5:1 mass ratio and placed into a brand-new quartz tube with an inner diameter of 18 mm. The mixture was then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 330°C at a rate of 5°C / min, held for 1200 min, and then naturally cooled to room temperature. Obvious clusters of black phosphorus crystals were visible on the wall of the quartz tube. Figure 8 As shown.

[0060] Comparative Example 1

[0061] Bismuth powder and red phosphorus powder were mixed at a mass ratio of 5:4 and placed into a brand new quartz tube with an inner diameter of 18 mm. The tube was then sealed under vacuum. The mixture was placed in a muffle furnace and heated to 300°C at a rate of 5°C / min. The temperature was maintained for 1500 min, and the mixture was allowed to cool naturally to room temperature. No obvious black phosphorus crystal clusters were formed on the wall of the quartz tube.

[0062] Comparative Example 2

[0063] The preparation method of high-purity black phosphorus crystals in this embodiment includes the following steps:

[0064] Bismuth and iodine particles were mixed at a molar ratio of 1:3 and placed into a brand-new quartz tube with an inner diameter of 18 mm, then vacuum-sealed. The mixture was placed in a muffle furnace and heated to 300°C at a rate of 5°C / min, held for 1080 min, and then naturally cooled to room temperature to obtain a product with a specific composition. This product was then mixed with red phosphorus powder at a mass ratio of 5:1, placed into a brand-new quartz tube with an inner diameter of 18 mm, and vacuum-sealed. The mixture was placed in a muffle furnace and heated to 300°C at a rate of 5°C / min, held for 1500 min, and then naturally cooled to room temperature. No obvious black phosphorus crystal clusters were observed on the quartz tube wall.

[0065] In summary, the molten salt method for preparing black phosphorus crystals adopted in this invention can produce black phosphorus crystals with a significantly reduced preparation temperature, which can relatively reduce energy consumption. The prepared black phosphorus crystals are of superior quality and high purity. The preparation process is mild, simple, and has relatively low equipment requirements, making it easy to implement.

[0066] This 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 a certain proportion and placing them in a reactor, and carrying out the corresponding reaction through heat treatment to obtain a bismuth-iodine molten mixture of the corresponding components; Step 2, sealing red phosphorus and the molten mixture in a certain proportion in a reactor, and carrying out the corresponding reaction through heat treatment to obtain black phosphorus crystals.

[0067] The method for preparing black phosphorus crystals using low-temperature melt transport provided in this application first prepares a Bi-BiI3 molten mixture in a specific ratio using bismuth and iodine as raw materials under vacuum conditions through a specific heat treatment program. This mixture is then mixed with red phosphorus, and under vacuum conditions, a specific heat treatment program is followed to finally obtain black phosphorus crystals. The method features a low reaction temperature, effectively reducing energy consumption. Furthermore, compared to other preparation methods, this method has lower requirements for related equipment, thereby reducing the overall preparation difficulty and cost.

[0068] In this application, the method utilizes a Bi-I molten salt system, eliminating the need for mineralizing agents and transporting agents, thus saving a significant amount of non-phosphorus raw materials. Furthermore, the Bi-I molten salt prepared in this invention can be recycled. Additionally, only red phosphorus needs to be added in subsequent preparation processes, achieving black phosphorus crystal preparation at a minimum temperature of 270°C, further reducing the production cost of black phosphorus. The method of this invention, employing a molten salt method, eliminates the safety hazards caused by phosphorus volatilization, and its simple and clear process route has the potential for large-scale industrial production, thereby promoting the application and development of black phosphorus.

[0069] Those skilled in the art will understand that the above-described embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A method for preparing black phosphorus crystal by low-temperature melt transport, characterized in that, The method comprises the following steps: Step one, mix metal bismuth and iodine in proportion and place them in a reactor, carry out corresponding reaction through heat treatment, and obtain a bismuth-iodine molten mixture of corresponding components; Step two, seal red phosphorus and the molten mixture in proportion in a reactor, carry out corresponding reaction through heat treatment, and obtain black phosphorus crystals; In step one, when the metal bismuth and iodine are mixed in proportion, the molar ratio of the metal bismuth and iodine is 5:(5-9); when the reactor is placed in a muffle furnace for heat treatment, it is heated from room temperature to 270-350 ℃, the heating time is 60-240 min, the holding time is 120-1440 min, and then it is cooled to room temperature, and the cooling time is 100-500 min; In step two, when the reactor is placed in a muffle furnace for heat treatment, it is heated from room temperature to 240-350 ℃, the heating time is 30-240 min, the holding time is 120-6000 min, and then it is cooled to room temperature, and the cooling time is 50-300 min.

2. The method for preparing black phosphorus crystals by low-temperature melt transport according to claim 1, characterized in that, In step one, the reactor containing the mixture of metal bismuth and iodine is placed in a muffle furnace for temperature rise to carry out corresponding reaction.

3. The method of claim 1, wherein the temperature is between 300 and 400 °C. The heating time is 90-180 min, and the cooling time is 180-300 min.

4. The method of claim 1, wherein the temperature is between 300 and 400 °C. The heating time is 60-120 min, and the cooling time is 90-240 min.

5. The method of claim 1, wherein the temperature is between 300 and 400 °C. The reactor is a vacuum sealed reactor.

6. The method of claim 1, wherein the temperature is between 300 and 400 °C. The material of the reactor comprises one of stainless steel, boron nitride, alumina, silicon carbide, silicon nitride or quartz.

7. The method of claim 1, wherein the temperature is between 300 and 400 °C. The state of the metal bismuth comprises powder or granular state; the state of the iodine comprises granular, block or powder state; and the state of the red phosphorus comprises powder or granular state.

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