InSeI single crystal preparation method based on water bath and double transport

Abstract

The invention provides an InSeI single crystal preparation method based on water bath and double transport, which comprises the following steps: taking simple substance In, simple substance Se and simple substance I2 as raw materials, and transferring the raw materials weighed in proportion into a prepared vacuum sealed quartz tube; putting the quartz tube into a water bath kettle, and uniformly mixing the raw materials by using a water bath method; carrying out high-temperature heating on the uniformly mixed sample; placing the obtained uniformly mixed raw materials at one end of a quartz tube, placing the quartz tube into a double-temperature-zone tubular furnace for growth, firstly placing one end filled with the raw materials in a low-temperature zone, placing the other end of the quartz tube in a high-temperature zone, and carrying out reverse transportation; placing one end filled with the raw materials in a high-temperature area, placing the other end in a low-temperature area, and finally cooling to room temperature after heating treatment to finally obtain the InSeI single crystal. The method is low in cost and simple in process, the reaction process is easy to control, impurities are not easy to introduce, and the high-quality and high-yield InSeI single crystal can be obtained more easily.

Description

Technical Field

[0001] The present invention relates to a method for preparing InSeI single crystals based on water bath and double transport, belonging to the technical field of crystal preparation. Background Art

[0002] Metal-based sulfohalides are a class of compounds composed of metals, chalcogens, and halogens. Due to their excellent optoelectronic properties, such as tunable bandgap, high light absorption coefficient, good carrier mobility, and environmental friendliness, these materials have received extensive attention in the optoelectronic field in recent years. For example, SnSI can be used in flexible photodetectors and field-effect transistors, BiSI can be used in high-sensitivity photodetectors, and CsSnI3 can be used to stabilize perovskite solar cells and light-emitting diodes. InSeI crystals also have important research value.

[0003] Currently, the traditional preparation methods of InSeI crystals include: chemical vapor transport method (CVT), vacuum sealed tube technology, etc. The processes mainly include: (1) first synthesizing In2Se3 crystals and then reacting with InI3 to obtain; (2) first synthesizing In2Bi3Se7I quaternary crystals and then thermally decomposing them to obtain InSeI crystals in the form of by-products. However, for the above methods, high cost, complex processes, and difficult control of the reaction process are all prone to introducing impurities, which is not conducive to obtaining high-quality InSeI crystals. Therefore, it is very necessary to develop a simple, effective, and high-quality preparation technology and process for pure InSeI crystals for the property research and application of this material. Summary of the Invention

[0004] Aiming at the above problems, the purpose of the present invention is to provide a method for preparing InSeI single crystals based on water bath and double transport, using high-purity elemental In, Se, and I2 as raw materials, and combining the water bath method, chemical vapor transport (CVT), and forward-backward double transport technology to prepare high-quality and pure InSeI single crystals.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: The present invention provides a method for preparing InSeI single crystals based on water bath and double transport, including: Using elemental In, elemental Se, and elemental I2 as raw materials, weighing them in proportion and placing them at one end of a quartz tube, evacuating and then sealing; Processing the sealed quartz tube by the water bath method to obtain uniformly mixed raw materials; Performing high-temperature treatment on the uniformly mixed raw materials and then cooling to room temperature; Placing the quartz tube after high-temperature treatment into a two-zone tube furnace, and placing the end with the raw materials in the low-temperature zone and the other end in the high-temperature zone for reverse transport; Switch the temperature so that one end containing the raw materials is in the high-temperature zone and the other end is in the low-temperature zone for forward transportation, and finally obtain InSeI single crystals.

[0006] Preferably, the molar ratio of the three elements In, Se, and I in the raw materials is 1:1: (1.01 - 1.05).

[0007] Preferably, the sealed quartz tube is treated by the water bath method, including: Vertically place the raw material end of the quartz tube in a constant temperature water bath, set the temperature to 65 - 95 °C, and maintain for 12 - 48 h.

[0008] Preferably, the temperature for the high-temperature treatment is set to 420 - 460 °C; during the high-temperature treatment, the temperature is raised from room temperature to the set temperature at a rate of 0.5 - 1 °C / min for 24 - 120 h, and then lowered from the high temperature to room temperature at a rate of 1 - 1.5 °C / min.

[0009] Preferably, the temperature of the low-temperature zone is set to 350 - 450 °C, and the temperature of the high-temperature zone is set to 450 - 550 °C; The heating rate is 0.5 - 1 °C / min.

[0010] Preferably, the temperature difference between the high-temperature zone and the low-temperature zone is 80 °C - 120 °C.

[0011] Preferably, during the reverse transportation, the growth time is 24 - 72 h.

[0012] Preferably, the switching of the temperature means that The high and low temperatures are switched within 1 h, so that the raw material area is in the high-temperature zone and the growth area is in the low-temperature zone.

[0013] Preferably, during the forward transportation, the growth time is 120 - 240 h.

[0014] Preferably, the method further includes: After the crystal growth is completed, it is cooled to room temperature at a rate of 0.5 - 1 °C / min, and InSeI single crystals are obtained from the low-temperature zone.

[0015] The beneficial effects achieved by the present invention are as follows: The present invention has low cost and a simple process. The reaction process is relatively easy to control, is not likely to introduce impurities, and it is easier to obtain high-quality and high-yield InSeI single crystals. Therefore, the present invention is a simple and effective preparation technology for obtaining high-quality pure InSeI single crystals. Description of the Drawings

[0016] Figure 1Schematic diagram of the operation process of a preparation method of InSeI single crystal based on water bath and double transport provided by an embodiment of the present invention; Figure 2 Optical microscope photograph of the InSeI single crystal prepared in Example 1 of the present invention; Figure 3 Raman spectrum of the InSeI single crystal prepared in Example 1 of the present invention; Figure 4 SEM photograph of the InSeI single crystal prepared in Example 1 of the present invention; Figure 5 EDS spectrum of the material composition of the InSeI single crystal prepared in Example 1 of the present invention; Figure 6 Sample spectrum prepared in Comparative Example 1 of the present invention; Figure 7 Optical microscope photograph of the InSeI single crystal prepared in Example 2 of the present invention; Figure 8 SEM photograph of the InSeI single crystal prepared in Example 2 of the present invention; Figure 9 EDS spectrum of the material composition of the InSeI single crystal prepared in Example 2 of the present invention; Figure 10 Sample spectrum prepared in Comparative Example 2 of the present invention; Figure 11 Optical microscope photograph of the InSeI single crystal prepared in Example 3 of the present invention; Figure 12 SEM photograph of the InSeI single crystal prepared in Example 3 of the present invention; Figure 13 Sample spectrum prepared in Comparative Example 3 of the present invention. Detailed implementation manners

[0017] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in combination with the implementation manners and the accompanying drawings. Herein, the illustrative implementation manners and descriptions of the present invention are used to explain the present invention, but do not limit the present invention.

[0018] Herein, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution according to the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0019] It should be emphasized that the term "including / comprising" when used herein refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0020] It should be emphasized here that the step marks mentioned hereinafter do not limit the sequence of each step. Instead, it should be understood that the steps can be executed in the order mentioned in the embodiments, or different from the order in the embodiments, or several steps can be executed simultaneously.

[0021] Based on high-purity elemental In, Se, and I2 as raw materials, the present invention combines the water bath method, chemical vapor transport (CVT), and forward-reverse double transport technology to prepare high-quality and pure InSeI single crystals.

[0022] In one embodiment, a method for preparing InSeI single crystals based on a water bath and double transport includes: S1. Weigh elemental In, elemental Se, and elemental I2 as raw materials in proportion. In this embodiment, using In, Se, and I2 as raw materials, they are uniformly mixed. Since elemental I2 is volatile, especially during the high-temperature sealing tube process, it volatilizes relatively fast. When selecting raw materials, a slightly excessive amount of I2 elemental should be selected. For example, the molar ratio of the three elements In, Se, and I in the raw materials can be 1:1: (1.01 - 1.05), preferably 1:1:1.02.

[0023] S2. Load the weighed elemental In, elemental Se, and elemental I2 into a quartz tube, place them at one end of the quartz tube, evacuate and then seal it. In this embodiment, to ensure that the quartz tube is free of impurities and moisture, the fired quartz tube can be ultrasonically cleaned with acetone and deionized water in turn for 30 minutes each. Then, dry the quartz tube in an oven for later use.

[0024] In a glove box protected by argon, transfer the weighed raw materials in proportion to the prepared quartz tube, use a vacuum pump to evacuate the air in the quartz tube to a vacuum of 10 -4 Pa, and finally seal the tube with a hydrogen-oxygen flame.

[0025] S3. Place the sealed quartz tube in a constant temperature water bath to obtain a uniformly mixed raw material. See Figure 1 , in this embodiment, place the raw material end of the quartz tube vertically in the constant temperature water bath, set the temperature to 65 - 95 °C, and maintain it for about 12 - 48 hours. Use the water bath method to uniformly and fully mix the three elemental raw materials.

[0026] S4. Perform high-temperature treatment on the uniformly mixed raw material and then cool it to room temperature. In this embodiment, the uniformly mixed raw materials are subjected to high-temperature treatment, and the temperature of the high-temperature treatment is set to 420-460 °C; during the high-temperature treatment, the temperature is raised from room temperature to the set temperature at a rate of 0.5-1 °C / min, lasting for 24-120 h, and then lowered from the high temperature to room temperature at a rate of 1-1.5 °C / min.

[0027] S5. Place the quartz tube after high-temperature treatment into a two-temperature-zone tube furnace, and place the end with the raw materials in the low-temperature zone and the other end in the high-temperature zone for reverse transport. See Figure 1 , in this embodiment, the sealed quartz tube is placed in a two-temperature-zone tube furnace, and the high-temperature zone and the low-temperature zone of the two-temperature-zone tube furnace are respectively raised to 450-550 °C and 350-450 °C. To prevent the vapor pressure of I2 from being too high and finally causing the quartz tube to burst, the heating rate can be controlled at 0.5-1 °C / min. Place the end with the raw materials in the low-temperature zone and the other end in the high-temperature zone, and keep it for 24-72 h to ensure that the target growth area of the quartz tube is clean and avoid crystal nucleation.

[0028] It should be noted that if the temperature difference is too low, the driving force for transportation is insufficient and InSeI single crystals cannot be generated. If the temperature difference is too large, InSeI polycrystals will be produced. Based on this, in this embodiment, the temperature difference between the high-temperature zone and the low-temperature zone is 80 °C-120 °C, and the preferred temperature difference is 100 °C.

[0029] S6. Switch the temperature so that the end with the raw materials is in the high-temperature zone and the other end is in the low-temperature zone for growth, and finally obtain InSeI single crystals.

[0030] See Figure 1 , in this embodiment, the high and low temperature switching is completed within 1 h, so that the raw material area is in the high-temperature zone and the growth area is in the low-temperature zone for InSeI single crystal growth, and the growth cycle is about 120-240 h. After the crystal growth is completed, it is cooled to room temperature at a rate of 0.5-1 °C / min.

[0031] In one embodiment, for reverse transport, the temperature of the low-temperature zone is set to 450 °C, the temperature of the high-temperature zone is set to 550 °C, and the heating treatment time is 48 h. The high and low temperature zones are switched within 1 h, the temperature of the low-temperature zone is set to 450 °C, the temperature of the high-temperature zone is set to 550 °C, and the heating treatment time is 120-240 h.

[0032] After the crystal growth is completed, cut the quartz tube and take out the InSeI single crystal at the low-temperature zone end. In the present invention, the temperature, holding time, vacuum degree, temperature difference, etc. of the high and low temperature zones during the crystal growth process all affect the quality of the single crystal.

[0033] For a further detailed description of the present invention, the following examples are based on the preparation method of InSeI single crystals based on water bath and double transport provided by the present invention to prepare InSeI single crystals, and the obtained crystals are subjected to optical photography and material composition determination. Unless otherwise specified, a centimeter ruler is used as a reference to photograph the obtained crystals, and the size of the obtained crystals is generally at the mm level, and some can reach the cm level. Example 1

[0034] Put three elements of In, Se, and I in a molar ratio of 1:1:1.02, namely In, Se, and I2, into the reaction vessel. Specifically, take 2.2964 g of In by mass (actual mass 2.2765 g), take 1.5792 g of Se by mass (actual mass 1.5655 g), and take 2.5381 g of I2 by mass (actual mass 2.5161 g).

[0035] To ensure that the quartz tube is free of impurities and moisture, the fired quartz tube can be ultrasonically cleaned successively with acetone and deionized water for 30 min each. Then dry the quartz tube in an oven for standby.

[0036] In the glove box protected by argon, transfer the weighed raw materials in proportion to the prepared quartz tube, and use a vacuum pump to evacuate the air in the quartz tube to a vacuum of 10 -4 Pa, and finally seal the tube with a hydrogen-oxygen flame.

[0037] Use the water bath heating method to make the raw materials mix evenly. Vertically place the raw material end of the quartz tube in a constant temperature water bath for high-temperature treatment, and the temperature of the high-temperature treatment is set at 450 °C; among them, rise from room temperature to the set temperature at a rate of 0.7 °C / min for 48 h, and then cool from the high temperature to room temperature at a rate of 1.2 °C / min.

[0038] Then place the quartz tube horizontally in a two-temperature zone tube furnace for heating. Set the high-temperature zone and low-temperature zone of the two-temperature zone tube furnace to rise to 550 and 450 °C respectively, place the end with the raw materials in the 450 °C low-temperature zone and the other end in the 550 °C high-temperature zone for reverse transport to make the growth area of the quartz tube clean, and the heating treatment time is 48 h.

[0039] Complete the high and low temperature switching within 1 h, heat the end with the raw materials to 550 °C, and cool the other end to 450 °C for growth, and the heating treatment time is 168 h. After the crystal growth is completed, cool to room temperature at a rate of 0.7 °C / min. Finally, obtain InSeI single crystals from the low-temperature end. Figure 2 This is an optical microscope photograph of the InSeI single crystal prepared in Example 1 of the present invention. Figure 3 This is the Raman spectrum of the InSeI single crystal prepared in Example 1. The InSeI single crystal can be determined by analyzing the Raman spectrum; Figure 4and Figure 5 Figure 2(a) and 2(b) are respectively the SEM photographs and EDS element composition and composition ratio test spectra of the InSeI single crystal prepared in Example 1. It can be analyzed that the obtained InSeI single crystal is of high quality and pure. Table 1 below shows that the atomic ratio in Example 1 is close to 1:1:1 and close to the nominal composition.

[0040] Table 1 Atomic ratio of the InSeI single crystal prepared in Example 1

[0041] Comparative Example 1 Put three elements of In, Se, and I₂ with a molar ratio of 1:1:1.02 into a reaction vessel. Specifically, take 2.2964 g of In (actual mass 2.2765 g), take 1.5792 g of Se (actual mass 1.5655 g), and take 2.5381 g of I₂ (actual mass 2.5161 g).

[0042] To ensure that the quartz tube is free of impurities and moisture, the fired quartz tube can be ultrasonically cleaned successively with acetone and deionized water for 30 min each. Then dry the quartz tube in an oven for later use.

[0043] In a glove box protected by argon, transfer the weighed raw materials in proportion to the prepared quartz tube, and use a vacuum pump to pump the air in the quartz tube to a vacuum of 10 -4 Pa, and finally seal the tube with a hydrogen-oxygen flame.

[0044] Using the water bath heating method, make the raw materials mix evenly. Place the raw material end of the quartz tube vertically in a constant temperature water bath for high-temperature treatment. The high-temperature treatment temperature is set at 450 °C; where it is heated from room temperature to the set temperature at a rate of 0.7 °C / min for 48 h, and then cooled from the high temperature to room temperature at a rate of 1.2 °C / min.

[0045] Then place the quartz tube horizontally in a two-temperature zone tube furnace for heating. Set the high-temperature zone and low-temperature zone of the two-temperature zone tube furnace to 550 °C and 450 °C respectively. Place the end with the raw materials in the 450 °C low-temperature zone and the other end in the 550 °C high-temperature zone for growth, and the heating treatment time is 168 h.

[0046] Comparative Example 1 is a control experiment for Example 1, Figure 6 which is the sample spectrum prepared in Comparative Example 1 of the present invention. In this Comparative Example 1, the double-transport method was not adopted, and a pure InSeI single crystal could not be obtained. Example 2

[0047] Put the three elements of In, Se, and I₂ with a molar ratio of In, Se, and I of 1:1:1.05 into the reaction vessel. Take 4.5928 g of In by mass (actual mass 4.6300 g), take 3.1584 g of Se by mass (actual mass 3.1840 g), and take 5.2255 g of I₂ by mass (actual mass 5.2376 g).

[0048] To ensure that the quartz tube is free of impurities and moisture, the fired quartz tube can be ultrasonically cleaned successively with acetone and deionized water for 30 minutes each. Then dry the quartz tube in the oven for later use.

[0049] In the glove box protected by argon, transfer the weighed raw materials in proportion to the prepared quartz tube, and use a vacuum pump to pump the air in the quartz tube to a vacuum of 10 -4 Pa, and finally seal the tube with a hydrogen-oxygen flame.

[0050] Use the water bath heating method to make the raw materials mix evenly. Vertically place the raw material end of the quartz tube in a constant temperature water bath for high-temperature treatment. The high-temperature treatment temperature is set at 450 °C; among them, it is heated from room temperature to the set temperature at a rate of 0.7 °C / min for 48 h, and then cooled from the high temperature to room temperature at a rate of 1.2 °C / min.

[0051] Then place the quartz tube horizontally in a two-temperature zone tube furnace for heating. Set the high-temperature zone and low-temperature zone of the two-temperature zone tube furnace to 510 and 430 °C respectively. Place the end with the raw materials in the 430 °C low-temperature zone and the other end in the 510 °C high-temperature zone for reverse transport to make the growth area of the quartz tube clean. The heating treatment time is 48 h.

[0052] Complete the high and low temperature switching within 1 h. Heat the end with the raw materials to 510 °C and cool the other end to 430 °C for growth. The heating treatment time is 120 h. After crystal growth is completed, cool to room temperature at a rate of 0.5 °C / min. Finally, obtain the InSeI single crystal from the low-temperature end. Figure 7 This is the optical microscope photograph of the InSeI single crystal prepared in Example 2 of the present invention. Figure 8 and Figure 9 Respectively are the SEM photograph of the InSeI single crystal prepared in this Example 2 and the test spectra of the EDS element composition and composition ratio. It can be analyzed that the obtained InSeI single crystal is of high quality and pure. The following Table 2 shows that the atomic ratio in Example 2 is close to 1:1:1 and close to the nominal composition.

[0053] Table 2 Atomic ratio of the InSeI single crystal prepared in Example 2

[0054] Comparative Example 2 Put the three elements of In, Se, and I in the molar ratio of 1:1:1.05, namely In, Se, and I₂, into the reaction vessel. Take 4.5928 g of In (actual mass 4.6300 g), 3.1584 g of Se (actual mass 3.1840 g), and 5.2255 g of I₂ (actual mass 5.2376 g).

[0055] To ensure that the quartz tube is free of impurities and moisture, the fired quartz tube can be ultrasonically cleaned successively with acetone and deionized water for 30 minutes each. Then dry the quartz tube in the oven for later use.

[0056] In the glove box under argon protection, transfer the weighed raw materials in proportion to the prepared quartz tube. Use a vacuum pump to evacuate the air in the quartz tube to a vacuum of 10 -4 Pa, and finally seal the tube with a hydrogen-oxygen flame.

[0057] Then place the quartz tube horizontally in a two-temperature-zone tube furnace for heating. Set the high-temperature zone and low-temperature zone of the two-temperature-zone tube furnace to rise to 510 and 430 °C respectively. Place the end with the raw materials in the 430 °C low-temperature zone and the other end in the 510 °C high-temperature zone for reverse transport to keep the growth area of the quartz tube clean. The heating treatment time is 48 h.

[0058] Complete the high-low temperature switching within 1 h. Raise the temperature of the end with the raw materials to 510 °C and lower the temperature of the other end to 430 °C for growth. The heating treatment time is 120 h. After crystal growth is completed, cool down to room temperature at a rate of 0.5 °C / min.

[0059] Comparative Example 2 is a control experiment for Example 2. Figure 10 For the sample spectrum prepared in Comparative Example 2, Comparative Example 2 did not adopt the water bath heating method and failed to obtain a pure InSeI single crystal. Example 3

[0060] Put the three elements of In, Se, and I in the molar ratio of 1:1:1.02, namely In, Se, and I₂, into the reaction vessel. Take 9.1856 g of In (actual mass 9.2623 g), 6.3168 g of Se (actual mass 6.3616 g), and 10.1524 g of I₂ (actual mass 10.2345 g).

[0061] To ensure that the quartz tube is free of impurities and moisture, the fired quartz tube can be ultrasonically cleaned successively with acetone and deionized water for 30 minutes each. Then dry the quartz tube in the oven for later use.

[0062] In the glove box under argon protection, transfer the weighed raw materials in proportion to the prepared quartz tube. Use a vacuum pump to evacuate the air in the quartz tube to a vacuum of 10-4 Pa, and finally seal the tube with a hydrogen-oxygen flame.

[0063] Using the water bath heating method, the raw materials are evenly mixed. Vertically place the raw material end of the quartz tube in a constant temperature water bath for high-temperature treatment, and the temperature of the high-temperature treatment is set at 450 °C; where it is heated from room temperature to the set temperature at a rate of 0.7 °C / min for 48 h, and then cooled from the high temperature to room temperature at a rate of 1.2 °C / min.

[0064] Then place the quartz tube horizontally in a two-temperature zone tube furnace for heating. Set the high-temperature zone and low-temperature zone of the two-temperature zone tube furnace to 530 and 410 °C respectively, place the end with the raw materials in the 410 °C low-temperature zone and the other end in the 530 °C high-temperature zone for reverse transport, so that the growth area of the quartz tube is clean, and the heating treatment time is 48 h.

[0065] Complete the high and low temperature switching within 1 h, heat the end with the raw materials to 530 °C, and cool the other end to 410 °C for growth, and the heating treatment time is 240 h. After the crystal growth is completed, cool it to room temperature at a rate of 1 °C / min. Finally, obtain the InSeI single crystal from the low-temperature end. Figure 11 This is an optical microscope photograph of the InSeI single crystal prepared in Example 3 of the present invention. Figure 12 This is the SEM photograph of the InSeI single crystal prepared in this Example 3. It can be analyzed that the obtained InSeI single crystal is of high quality and pure. The following Table 3 shows that the atomic ratio in Example 3 is close to 1:1:1 and close to the nominal composition.

[0066] Table 3 Atomic ratio of the InSeI single crystal prepared in Example 3

[0067] Comparative Example 3 Put three single substances of In, Se, and I2 with an element molar ratio of 1:1:1.02 into a reaction vessel. Take 9.1856 g of In by mass (actual mass 9.2623 g), take 6.3168 g of Se by mass (actual mass 6.3616 g), and take 10.1524 g of I2 by mass (actual mass 10.2345 g).

[0068] To ensure that the quartz tube has no impurities and moisture, the fired quartz tube can be ultrasonically cleaned successively with acetone and deionized water for 30 min each. Then dry the quartz tube in an oven for standby.

[0069] In a glove box protected by argon, transfer the weighed raw materials in proportion to the prepared quartz tube, and use a vacuum pump to pump the air in the quartz tube to a vacuum of 10 -4 Pa, and finally seal the tube with a hydrogen-oxygen flame.

[0070] Using the water bath heating method, the raw materials are evenly mixed. The raw material end of the quartz tube is placed vertically in a constant temperature water bath for high-temperature treatment, and the temperature of the high-temperature treatment is set at 450 °C; among them, it is heated from room temperature to the set temperature at a rate of 0.7 °C / min for 48 h, and then cooled from the high temperature to room temperature at a rate of 1.2 °C / min.

[0071] Then the quartz tube is placed horizontally in a two-temperature zone tube furnace for heating. The high-temperature zone and the low-temperature zone of the two-temperature zone tube furnace are set to rise to 550 °C and 200 °C respectively. One end containing the raw materials is placed in the 200 °C low-temperature zone and the other end is placed in the 550 °C high-temperature zone for reverse transport, so that the growth area of the quartz tube is clean, and the heating treatment time is 48 h.

[0072] The high and low temperatures are switched within 1 h. One end containing the raw materials is heated to 550 °C, and the other end is cooled to 200 °C for growth, and the heating treatment time is 240 h. After crystal growth is completed, it is cooled to room temperature at a rate of 1 °C / min.

[0073] This Comparative Example 3 is a control experiment for Example 3. Figure 13 It is the sample spectrum prepared for Comparative Example 3. The preparation temperature at the low-temperature end of this Comparative Example 3 is too low, and a pure InSeI single crystal cannot be obtained.

[0074] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing InSeI single crystals based on water bath and double transport, characterized in that, Comprising: Taking elemental In, elemental Se and elemental I₂ as raw materials, weighing them in proportion and placing them at one end of a quartz tube, evacuating and then sealing; Processing the sealed quartz tube by the water bath method to obtain a uniformly mixed raw material; Performing high-temperature treatment on the uniformly mixed raw material and then cooling to room temperature; Placing the quartz tube after high-temperature treatment into a two-temperature-zone tubular furnace, and placing the end with the raw material in the low-temperature zone and the other end in the high-temperature zone for reverse transport; Switching the temperature so that the end with the raw material is in the high-temperature zone and the other end is in the low-temperature zone for forward transport, and finally obtaining an InSeI single crystal.

2. The method for preparing InSeI single crystal based on water bath and double transport according to claim 1, wherein, The molar ratio of the three elements In, Se, and I in the raw material is 1:1: (1.01 - 1.05).

3. A method for preparing InSeI single crystals based on water bath and double transport according to claim 1, characterized in that, The processing of the sealed quartz tube by the water bath method includes: Vertically placing the raw material end of the quartz tube in a constant-temperature water bath, setting the temperature to 65 - 95 °C and maintaining for 12 - 48 h.

4. A method for preparing InSeI single crystals based on water bath and double transport according to claim 1, characterized in that, The temperature for the high-temperature treatment is set to 420 - 460 °C; during the high-temperature treatment, it is heated from room temperature to the set temperature at a rate of 0.5 - 1 °C / min and maintained for 24 - 120 h, and then cooled from the high temperature to room temperature at a rate of 1 - 1.5 °C / min.

5. A method for preparing InSeI single crystal based on water bath and double transport according to claim 1, characterized in that, The temperature of the low-temperature zone is set to 350 - 450 °C, and the temperature of the high-temperature zone is set to 450 - 550 °C; The heating rate is 0.5 - 1 °C / min.

6. A method for preparing InSeI single crystals based on water bath and double transport according to claim 5, characterized in that, The temperature difference between the high-temperature zone and the low-temperature zone is 80 °C - 120 °C.

7. A method for preparing InSeI single crystal based on water bath and double transport according to claim 6, characterized in that, During the reverse transport, the growth time is 24 - 72 h.

8. A method for preparing InSeI single crystals based on water bath and dual transport according to claim 1, characterized in that, The switching of the temperature means that The high and low temperatures are switched within 1 h so that the raw material area is in the high-temperature zone and the growth area is in the low-temperature zone.

9. A method for preparing InSeI single crystals based on water bath and double transport according to claim 1, characterized in that, During the forward transport, the growth time is 120 - 240 h.

10. A method for preparing InSeI single crystal based on water bath and double transport according to claim 1, characterized in that, The method further includes: After the crystal growth is completed, it is cooled to room temperature at a rate of 0.5 - 1 °C / min, and the InSeI single crystal is obtained from the low-temperature zone.

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