Method for preparing high-quality, large-size bulk tin monophosphide single crystal

Abstract

The application provides a preparation method of high-quality and large-size bulk SnP3 monocrystal, and belongs to the technical field of SnP3 monocrystal preparation. ‑2 The application comprises the following steps: (1) tin powder and red phosphorus powder are mixed according to a molar ratio of 1:4, and a certain proportion of potassium chloride and aluminum chloride is added; (2) the raw materials in step (1) are loaded into a quartz tube for vacuum sealing, the vacuum degree in the quartz tube is 2*10 ‑2 Pa, and the raw materials are uniformly mixed by using a premixer; (3) the quartz tube after vacuum sealing in step (2) is sintered, the sintering temperature is set to 300-500 DEG C, the temperature holding time is 48-92 h, and the temperature rising rate is 3 DEG C / min; (4) the quartz tube after sintering in step (3) is cooled to room temperature, and the sample is cleaned to obtain SnP3 monocrystal. The application can ensure the preparation of high-quality and micron-level layered SnP3 monocrystal.

Description

Technical Field

[0001] This invention relates to a method for preparing high-quality, large-size bulk tin triphosphide single crystals, belonging to the field of new energy materials technology. In particular, it relates to a method for preparing high-quality, large-size bulk tin triphosphide single crystals and the micron-scale layered tin triphosphide single crystals prepared by this method. Background Technology

[0002] Tin triphosphide has a similar crystal structure to rhombohedral black phosphorus, and exhibits metallic conductivity, which is much higher than that of black phosphorus. The exfoliation energy of monolayer tin triphosphide is 0.45 J / m². -2 The stripping energy of black phosphorus (0.36 J m) -2 The small difference indicates that tin triphosphide is easily dissociated. Monolayer tin triphosphide has an ultra-low sodium ion migration barrier (0.03 eV), lower than that of monolayer black phosphorus (0.08 V), suggesting that monolayer tin triphosphide will have high ion mobility when used as an electrode material. Currently, the main methods for preparing tin triphosphide materials are the gas-phase method and the ball milling method. The tin triphosphide material prepared by the gas-phase method contains 3% Sn3P4, while the tin triphosphide prepared by the ball milling method has nanoscale grains and poor crystal quality. Summary of the Invention

[0003] In view of this, in order to solve the technical problems of low purity and small grain size of currently prepared bulk tin triphosphide materials, this invention provides a method for preparing high-quality, large-size bulk tin triphosphide single crystals. This method involves mixing materials in a premixer, using a molten salt method, and sintering in a muffle furnace, while controlling the heating rate at 3℃ / min and the temperature at 300-500℃. This successfully prepares high-quality, large-size bulk tin triphosphide materials, ensuring the preparation of micron-level layered tin triphosphide single crystals.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing high-quality, large-size bulk tin triphosphide single crystals includes the following steps:

[0006] Step (1): Mix tin powder and red phosphorus powder in a molar ratio of 1:4, and add a certain proportion of potassium chloride and aluminum chloride;

[0007] Step (2): The raw materials from step (1) are loaded into a quartz tube and vacuum sealed, and the raw materials are mixed evenly using a premixer;

[0008] Step (3): Sinter the quartz tube after vacuum sealing in step (2), set the sintering temperature to 300-500℃ and hold for 48-92h, with a heating rate of 3℃ / min.

[0009] Step (4): Cool the quartz tube after sintering in step (3) to room temperature, clean the sample, and obtain tin triphosphide single crystal.

[0010] Preferably, in step (1), the molar ratio of tin powder, red phosphorus powder, potassium chloride, and aluminum chloride is 1:4:(3.5-7):(1.75-3.5).

[0011] Preferably, in step (2), the premixer mixes the materials for 30-60 minutes.

[0012] Preferably, in step (2), the vacuum sealing of the quartz tube needs to be carried out in a glove box before the quartz tube is vacuum sealed.

[0013] Preferably, the oxygen content of the water is below 0.1 ppm.

[0014] Preferably, in step (2), the vacuum degree of the quartz tube during vacuum sealing is 2*10. -2 Below Pa.

[0015] Preferably, in step (4), the cleaning operation is ultrasonic treatment.

[0016] Preferably, the ultrasonic treatment conditions are an ultrasonic power of 100W and an ultrasonic time of 30-60min.

[0017] Preferably, in step (1), the tin powder and red phosphorus powder are untreated tin powder and red phosphorus powder.

[0018] On the other hand, the present invention also provides a high-quality, large-size bulk tin triphosphide single crystal, which is prepared by the above-mentioned method for preparing high-quality, large-size bulk tin triphosphide single crystal, wherein the tin triphosphide single crystal is of high quality and at the micron level.

[0019] The present invention provides a method for preparing high-quality, large-size bulk tin triphosphide single crystals. This method utilizes a mixing process, molten salt method, and muffle furnace sintering, controlling the heating rate at 3℃ / min and the temperature at 300-500℃. This successfully produces high-quality, large-size bulk tin triphosphide material, offering the following advantages compared to existing technologies:

[0020] (1) This invention overcomes the technical defect that it is difficult to prepare high-purity, large-size tin triphosphide single crystals, and realizes the preparation of high-purity tin triphosphide single crystals with a crystal size of up to 178.43 μm, providing original materials for subsequent research on the physical properties of tin triphosphide crystals.

[0021] (2) The present invention uses molten salt sintering technology to prepare tin triphosphide single crystals. Compared with the traditional gas phase method and ball milling method, it has a shorter production cycle, larger crystal size and higher crystal purity.

[0022] (3) This method can prepare tin triphosphide crystals in large quantities. By increasing the size of the quartz tube, gram-level tin triphosphide crystals can be prepared in one go, which is of great significance for the subsequent research on tin triphosphide crystals.

[0023] (4) The high-quality, large-size tin triphosphide crystals prepared by the molten salt method of this invention can be used as precursors for the preparation of two-dimensional tin triphosphide crystals, which can ensure the preparation of micron-level two-dimensional tin triphosphide crystals. Attached Figure Description

[0024] Figure 1 The XRD pattern of the bulk tin triphosphide sample obtained in Example 1;

[0025] Figure 2 Raman spectroscopy of the bulk tin triphosphide sample obtained in Example 1;

[0026] Figure 3 The images are scanning electron microscope (SEM) images of the bulk tin triphosphide sample obtained in Example 1. a and b are SEM images of the bulk tin triphosphide sample at different magnifications, respectively.

[0027] Figure 4 The image shows the scanning electron microscope (SEM) energy dispersive spectroscopy (EDS) spectrum of the bulk tin triphosphide sample obtained in Example 1. Figure 4 In the image, a is a scanning electron microscope image, b is a magnified image of a specified area in a, and ce is an energy dispersive X-ray spectroscopy (EDX) image of the specified area in a.

[0028] Figure 5 XRD patterns of bulk tin triphosphide samples obtained in Examples 1-4 and Comparative Examples 1-2;

[0029] Figure 6 This is a scanning electron microscope image of the bulk tin triphosphide sample obtained in Example 2;

[0030] Figure 7 The image shows a scanning electron microscope (SEM) image of the bulk tin triphosphide sample obtained in Comparative Example 2.

[0031] Figure 8 The image shows a scanning electron microscope (SEM) image of the bulk tin triphosphide sample obtained in Comparative Example 3.

[0032] Figure 9 The image shows a scanning electron microscope (SEM) image of the bulk tin triphosphide sample obtained in Comparative Example 4. Detailed Implementation

[0033] This invention provides a method for preparing high-quality, large-size bulk tin triphosphide single crystals, comprising the following steps:

[0034] Step (1): Mix tin powder and red phosphorus powder in a molar ratio of 1:4, and add a certain proportion of potassium chloride and aluminum chloride. If the molar ratio of tin powder to red phosphorus powder is lower than 1:4 during the tube sealing and sintering process, Sn4P3 impurities will appear in the single crystal produced by the tube sealing process; if the molar ratio of tin powder to red phosphorus powder is higher than 1:4, black phosphorus impurities will appear during the subsequent high-temperature sintering process; therefore, in order to prepare high-purity tin triphosphide crystals, the molar ratio of tin powder to red phosphorus powder is set to 1:4.

[0035] Potassium chloride and aluminum chloride are used as co-solvents. The tin powder and red phosphorus powder are preferably untreated tin powder and red phosphorus powder. Untreated means that purchased raw materials are used without further purification. The molar ratio of tin powder, red phosphorus powder, potassium chloride, and aluminum chloride is preferably 1:4:(3.5-7):(1.75-3.5), more preferably 1:4:3.5:1.75.

[0036] Step (2): Load the raw materials from step (1) into a quartz tube and vacuum seal it. Then, use a premixer to mix the raw materials evenly. Preferably, the premixer is used for 30-60 minutes. Before vacuum sealing the quartz tube, the sample needs to be loaded into a glove box, preferably with a water-oxygen value below 0.1 ppm. Preferably, in step (2), the vacuum degree of the quartz tube during vacuum sealing is 2*10⁻⁶. -2 Below Pa, that is, a vacuum degree of 2*10 -2 Anything below Pa is acceptable.

[0037] Step (3): Sinter the quartz tube after vacuum sealing in step (2). Set the sintering temperature to 300-500℃ and hold for 48-92 hours. The heating rate is 3℃ / min. In the muffle furnace sintering step, the heating rate and sintering temperature are key factors affecting the purity and grain size of bulk tin triphosphide. The heating rate is controlled at 3℃ / min. The optimal temperature for obtaining high-purity, large-size tin triphosphide is 400℃. As the temperature increases, tin triphosphide decomposes into black phosphorus and Sn4P3, while the tin triphosphide grains cannot grow if the temperature decreases.

[0038] Step (4): Cool the quartz tube after sintering in step (3) to room temperature, and clean the sample to obtain tin triphosphide single crystals. The cleaning operation is ultrasonic treatment, specifically: the sample is placed in deionized water for ultrasonic treatment with an ultrasonic power of 100W and an ultrasonic time of 30min to remove chloride and obtain tin triphosphide single crystals.

[0039] The technical solution of the present invention will be clearly and thoroughly described below with reference to specific embodiments.

[0040] For any techniques or conditions not specified in the examples, please follow the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available standard products.

[0041] Example 1

[0042] (1) Using tin powder and red phosphorus powder as raw materials, the oxygen content of the glove box is 0.05 ppm. The molar ratio of tin powder and red phosphorus powder is selected as 1:4, and potassium chloride and aluminum chloride with a molar ratio of 3.5:1.75 are added as co-solvents.

[0043] (2) Place the above-mentioned mixed powder into an 8mm diameter quartz tube; and mix the raw materials evenly using a premixer for 45 minutes. Then, use a vacuum sealing machine to seal the tube at a vacuum degree of 2*10. -2 Below Pa, a closed quartz tube is used.

[0044] (3) The quartz tube is placed in the muffle furnace, and the sintering temperature is set to 400℃ and held for 92 hours. The heating rate is 3℃ / min.

[0045] (4) After sintering, wait for the quartz tube to cool to room temperature, put the sample into deionized water for ultrasonic treatment, use ultrasonic power of 100W and ultrasonic time of 30min to remove chloride, and vacuum dry for 12h to obtain tin triphosphide single crystal.

[0046] Example 2

[0047] Same as Example 1, except that in step (3), the heat preservation time is 48h.

[0048] Example 3

[0049] Same as Example 1, except that in step (3), the sintering temperature is 500°C.

[0050] Example 4

[0051] Same as Example 1, except that in step (3), the sintering temperature is 300°C.

[0052] Example 5

[0053] Similar to Example 1, except that in step (1), potassium chloride and aluminum chloride are added in a molar ratio of 7:3.5.

[0054] Example 6

[0055] Similar to Example 1, except that in step (1), potassium chloride and aluminum chloride are added in a molar ratio of 5:2.5.

[0056] Comparative Example 1

[0057] Similar to Example 1, except that in step (1), potassium chloride and cesium chloride are selected as the co-solvents.

[0058] Comparative Example 2

[0059] Similar to Example 1, except that in step (1), the raw materials are tin powder and red phosphorus powder in a molar ratio of 1:3, without the addition of a co-solvent. The synthesis method of Comparative Example 2 is a conventional synthesis method in the prior art.

[0060] Comparative Example 3

[0061] Same as Example 1, except that in step (3), the heating rate is 5°C / min.

[0062] Comparative Example 4

[0063] Same as Example 1, except that in step (3), the heating rate is 1℃ / min.

[0064] Figure 1 The image shows the XRD pattern of the bulk tin triphosphide sample in Example 1. By comparing it with the standard PDF card, the successful preparation of high-purity tin triphosphide is demonstrated. Figure 2 The image shows the Raman spectrum of the bulk tin triphosphide sample in Example 1. The Raman spectrum reveals the dominant phase of tin triphosphide, located at 139, 246, 323, and 393 cm⁻¹. -1 The four bands can be respectively associated with feature A. 1 g、B 2g B 3g and A 2 g Vibration mode. Figure 3 The images are scanning electron microscope (SEM) images of the bulk tin triphosphide sample in Example 1 at different magnifications. In the images, a and b are SEM images of the bulk tin triphosphide sample at different magnifications. A clear layered structure can be seen from a and b. The largest tin triphosphide sheet is as high as 178.43 micrometers, which is much larger than the 100-nanometer-scale tin triphosphide particles prepared by ball milling. Figure 4 Image a is a scanning electron microscope (SEM) image of the bulk tin triphosphide sample; image b is a SEM image of the bulk tin triphosphide sample at magnification; image ce shows an energy-dispersive X-ray spectroscopy (EDX) image; and images d and e are elemental mapping images, showing that Sn and P elements are uniformly distributed with an atomic ratio of ~1:3, close to the ideal stoichiometric ratio. Figure 5 The images show the XRD patterns of bulk tin triphosphide samples from Examples 1-4 and Comparative Examples 1-2. Example 1 synthesized high-quality, high-purity tin triphosphide crystals. Example 2, due to its short holding time, successfully synthesized tin triphosphide, but the grains were relatively small. Example 3: When the sintering temperature was 500℃, impurities of Sn4P3 and black phosphorus appeared. Example 4: When the sintering temperature was 300℃, impurities of Sn4P3 and black phosphorus also appeared. Comparative Example 1: When the co-solvents were potassium chloride and cesium chloride, tin triphosphide could not be synthesized, and impurities of Sn4P3 and black phosphorus appeared. Comparative Example 2: When no co-solvent was added, tin triphosphide could be synthesized, but the grains were only a few micrometers in size. Figure 6 The image shows a scanning electron microscope (SEM) image of the bulk tin triphosphide sample obtained in Example 2. As can be seen from the image, the grains are relatively small due to the short holding time, and the grains grow as the holding time increases. Figure 7 The image shows a scanning electron microscope (SEM) image of the bulk tin triphosphide sample obtained in Comparative Example 2. Figure 7 It is clearly visible that the grains are only a few micrometers in size without the addition of a co-solvent. Figure 8 , 9 The images show scanning electron microscope (SEM) images of the bulk tin triphosphide samples obtained in Comparative Examples 3 and 4, respectively. The images demonstrate the effect of different heating rates on grain size. Both excessively fast and excessively slow heating rates are detrimental to grain growth.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing high-quality, large-size bulk tin triphosphide single crystals, characterized in that, Includes the following steps: Step (1): Mix tin powder and red phosphorus powder in a molar ratio of 1:4, and add a certain proportion of potassium chloride and aluminum chloride; Step (2): The raw materials from step (1) are loaded into a quartz tube and vacuum sealed, and the raw materials are mixed evenly using a premixer; Step (3): Sinter the quartz tube after vacuum sealing in step (2), set the sintering temperature to 300-500℃ and hold for 48-92h, with a heating rate of 3℃ / min. Step (4): Cool the quartz tube after sintering in step (3) to room temperature, clean the sample, and obtain tin triphosphide single crystal.

2. The method for preparing a high-quality, large-size bulk tin triphosphide single crystal according to claim 1, characterized in that, In step (1), the molar ratio of tin powder, red phosphorus powder, potassium chloride and aluminum chloride is 1:4:(3.5-7):(1.75-3.5).

3. The method for preparing a high-quality, large-size bulk tin triphosphide single crystal according to claim 1, characterized in that, In step (2), the premixer mixes the materials for 30-60 minutes.

4. The method for preparing a high-quality, large-size bulk tin triphosphide single crystal according to claim 1, characterized in that, In step (2), the vacuum sealing of the quartz tube needs to be carried out in a glove box before the tube is vacuum sealed.

5. The method for preparing a high-quality, large-size bulk tin triphosphide single crystal according to claim 4, characterized in that, The oxygen level in the glove box is below 0.1 ppm.

6. The method for preparing a high-quality, large-size bulk tin triphosphide single crystal according to claim 1, characterized in that, In step (2), the vacuum degree of the quartz tube during vacuum sealing is 2*10. -2 Below Pa.

7. The method for preparing a high-quality, large-size bulk tin triphosphide single crystal according to claim 1, characterized in that, In step (4), the cleaning operation is ultrasonic treatment.

8. The method for preparing a high-quality, large-size bulk tin triphosphide single crystal according to claim 7, characterized in that, The ultrasonic treatment conditions are: ultrasonic power 100W and ultrasonic time 30-60min.

9. A method for preparing high-quality, large-size bulk tin triphosphide single crystals according to any one of claims 1-8, characterized in that, In step (1), the tin powder and red phosphorus powder are untreated tin powder and red phosphorus powder.

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