Type II red phosphorus single crystal wafer material and preparation method thereof

Abstract

The invention discloses a type II red phosphorus single crystal wafer material and a preparation method thereof, and belongs to the technical field of red phosphorus preparation. Red phosphorus and a mineralizing agent are used as precursors for heating reaction, the mineralizing agent is used for inducing red phosphorus sublimation to obtain oriented transformation of a red phosphorus gas molecular structure, and two cooling stages are accurately regulated and controlled, so that the type II red phosphorus single crystal wafer material is obtained. The red phosphorus gas molecules are subjected to structural recombination and conversion, the II-type red phosphorus single crystal wafer material with the characteristic size of 100-500 microns is prepared, and the stability and high yield (gt) of the II-type red phosphorus single crystal wafer material are realized; the crystal structure of the II-type red phosphorus single crystal wafer is successfully analyzed, and the requirements of single crystal wafer-based device processing and anisotropic intrinsic physical property accurate measurement are met.

Description

Technical Field

[0001] This invention belongs to the field of red phosphorus preparation technology, specifically relating to a type II red phosphorus single crystal wafer material and its preparation method. Background Technology

[0002] Phosphorus exists in various allotropes, among which type II red phosphorus, a key allotrope of elemental phosphorus, exhibits remarkable potential in infrared photonics, high-capacity energy storage, and catalysis due to its unique twisted tubular wave-like stacked structure. Theoretical calculations and preliminary experiments show that this structure endows it with significant anisotropy, especially in optics, exhibiting a stronger polarization-dependent response than black phosphorus and purple phosphorus, making it a promising candidate for applications in polarization-sensitive photodetectors, integrated waveguides, nonlinear optical devices, and high-capacity energy storage.

[0003] The practical application of type II red phosphorus has long been limited by the challenge of controlling the production of high-yield, large-size single-crystal materials. Its preparation technology faces major bottlenecks. Specifically, type II red phosphorus is thermodynamically metastable. Traditional vacuum annealing or gas-phase transport methods, due to imprecise temperature window control during synthesis, easily generate other thermodynamically stable phosphorus allotropes such as purple phosphorus and fibrous phosphorus as impurities, making it difficult to obtain a single-phase product. For example, early methods often produced multiphase mixtures or microcrystalline aggregates with extremely low crystallinity. Furthermore, existing synthesis routes (such as partially solvothermal methods or short-cycle gas-phase methods) typically only yield nanorods, nanosheets, or micron-sized crystals. These products are small in size and have many defects, failing to meet the requirements for device fabrication based on single-crystal wafers and precise measurement of anisotropic intrinsic properties. The bottleneck of crystal size directly hinders its macroscopic functional applications. In addition, some methods use highly reactive white phosphorus as a precursor, which poses safety hazards and pollution risks; while chemical vapor transport methods using halogens such as iodine as transport agents can improve crystallinity, but may introduce impurities and corrode equipment, and have long growth cycles and unsatisfactory yields, making it difficult to achieve efficient, stable and safe large-scale preparation. Summary of the Invention

[0004] This invention provides a type II red phosphorus single crystal wafer material and its preparation method. Existing type II red phosphorus preparation technology has technical problems such as inaccurate temperature control, generation of purple phosphorus, other crystalline phosphorus or phosphide impurities, affecting crystal phase purity and yield, as well as small size and many defects in existing synthesized products.

[0005] This invention uses a mixture of red phosphorus and a mineralizing agent to obtain a precursor; the precursor is heated to sublimate the red phosphorus and obtain red phosphorus gas molecules; the red phosphorus gas molecules are then structure-induced by the mineralizing agent; and a type II red phosphorus single crystal wafer material with high single-phase purity and a feature size of 100μm~500μm is synthesized by programmed cooling.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] The first objective of this invention is to provide a method for preparing type II red phosphorus single-crystal wafer material, comprising the following steps: The precursor is obtained by mixing red phosphorus and mineralizing agent at a mass ratio of 5 to 100:1. The precursor is heated to 580℃~620℃ to sublimate red phosphorus and obtain red phosphorus gas molecules. The red phosphorus gas molecules are then subjected to structural induction by a mineralizing agent and cooled to room temperature by programmed cooling to obtain type II red phosphorus single crystal wafer material.

[0008] The programmed cooling process is as follows: cooling to 450℃~500℃ at a rate of 0.1℃ / min~0.5℃ / min, holding at this temperature for 6h~36h, then cooling to 380℃~420℃ at a rate of 0.01℃ / min~0.05℃ / min, holding at this temperature for 10h~36h, and finally cooling to room temperature at a rate of 0.05℃ / min~0.5℃ / min. This programmed cooling is a precisely programmed temperature setting, with different cooling rates set in different temperature ranges to control supersaturation in stages. Cooling to 450℃~500℃ is the nucleation process; rapid cooling avoids competitive nucleation of type II and type V phosphorus, preventing the formation of impurity phases. The subsequent slow cooling to 380℃~420℃ is the crystallization process, making the crystal nucleus structure more complete and stable, followed by the crystal growth process. Precise programmed cooling first suppresses impurity phases and then promotes the main phase. Through kinetic control, the difference in nucleation kinetics between the main phase and impurity phases can be utilized to suppress the generation of multiple phases or defects, thereby improving the single phase and yield of the crystal.

[0009] As a preferred embodiment, the programmed cooling specifically involves: cooling to 460°C at a rate of 0.3°C / min, holding at that temperature for 6 hours, then cooling to 400°C at a rate of 0.03°C / min, holding at that temperature for 12 hours, and finally cooling to room temperature at a rate of 0.1°C / min. This program can both realize the superiority of competitive nucleation of type II phosphorus during the nucleation stage and ensure high yield and efficiency of type II phosphorus.

[0010] In a preferred embodiment, the heating rate to 580℃~620℃ is 1℃ / min~5℃ / min.

[0011] In a preferred embodiment, the red phosphorus is amorphous red phosphorus with a purity ≥99.999%.

[0012] In a preferred embodiment, the mineralizing agent is tin powder or lead powder with a purity ≥99.999%.

[0013] A second objective of this invention is to provide a type II red phosphorus single-crystal material prepared by the aforementioned preparation method.

[0014] In a preferred embodiment, the type II red phosphorus single crystal wafer material is a monoclinic crystal system with space group [space group missing]. P 21. Lattice constant a =13.1±0.1Å, b =34.5±0.1Å, c =18.8±0.1Å, β =109.7±0.1°.

[0015] In a preferred embodiment, the size of the type II red phosphorus single crystal wafer material is between 100 μm and 500 μm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The preparation method of Type II red phosphorus monocrystalline wafer material provided by this invention involves the directional transformation of the red phosphorus gas molecule structure obtained by the sublimation of red phosphorus induced by a mineralizing agent. This is mainly achieved through precise control of two cooling stages, which enables the red phosphorus gas molecules to undergo structural recombination and transformation during the cooling process. After the red phosphorus sublimation, the red phosphorus gas molecules first undergo a nucleation process during the cooling stage, that is, the structure of the red phosphorus gas molecules is opened up under the action of the mineralizing agent to achieve structural recombination. After being transported from the source region to the growth region, the phosphorus molecules undergo a crystallization process, and the structure between the molecules is rearranged and combined, transforming the red phosphorus gas structure into a red phosphorus monocrystalline wafer structure.

[0017] The Type II red phosphorus single crystal wafer material and its preparation method provided by this invention achieve highly safe and stable synthesis of Type II red phosphorus single crystal wafer materials with a size of 100μm~500μm, and ensure high yield (yield>90%). This provides a material basis for the analysis of the red phosphorus crystal structure and meets the requirements for device fabrication based on single crystal wafers and accurate measurement of anisotropic intrinsic properties. Attached Figure Description

[0018] Figure 1 These are optical images and product images of the Type II red phosphorus single-crystal wafer material prepared in Example 1 of the present invention. Specifically, a is an optical image of the Type II red phosphorus single-crystal wafer material prepared in Example 1 of the present invention; b is a product image of the prepared Type II red phosphorus single-crystal wafer material.

[0019] Figure 2 The crystal structure of the type II red phosphorus single crystal wafer material prepared in Example 1 of this invention is obtained by SCXRD analysis.

[0020] Figure 3 The image shows the XRD pattern of the type II red phosphorus single crystal wafer material prepared in Example 1 of this invention.

[0021] Figure 4The images show the product diagram and XRD pattern of the dark V-type red phosphorus material prepared in Comparative Example 1 of this invention. Specifically, a is the product diagram of the dark V-type red phosphorus material prepared in Comparative Example 1 of this invention; b is the XRD pattern of the dark V-type red phosphorus material prepared in Comparative Example 1 of this invention.

[0022] Figure 5 This is a diagram of the product prepared in Comparative Example 2 of the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0024] Type II red phosphorus, a key allotrope of elemental phosphorus, exhibits significant application potential in infrared photonics, high-capacity energy storage, and catalysis due to its unique twisted tubular wave-like stacked structure. However, its practical application has long been limited by the controllable preparation of high-yield, large-size single-crystal materials. The main challenges include imprecise temperature window control, the easy generation of other phosphorus allotropes as impurities, and the difficulty in obtaining single-phase products. Existing synthetic routes (such as partial solvothermal methods or short-cycle vapor-phase methods) typically only yield nanorods, nanosheets, or micron-sized crystals. These products are small in size and have many defects, failing to meet the requirements for device fabrication based on single-crystal wafers and precise measurement of anisotropic intrinsic properties. The crystal size bottleneck directly hinders its macroscopic functional applications. Furthermore, using highly reactive white phosphorus as a precursor poses safety hazards and pollution risks; chemical vapor transport methods using halogens such as iodine as transport agents may introduce impurities and corrode equipment, and have long growth cycles and unsatisfactory yields, making it difficult to achieve efficient, stable, and safe large-scale preparation. To address the aforementioned issues, this invention provides a type II red phosphorus single crystal wafer material and its preparation method.

[0025] The technical solution of the present invention will be analyzed in detail below.

[0026] This invention provides a type II red phosphorus single crystal wafer material and its preparation method, which involves mixing red phosphorus and a mineralizing agent at a mass ratio of 5 to 100:1 to obtain a precursor.

[0027] The precursor is heated to 580℃~620℃ to sublimate red phosphorus and obtain red phosphorus gas molecules. The red phosphorus gas molecules are then subjected to structural induction by a mineralizing agent and cooled to room temperature by programmed cooling to obtain type II red phosphorus single crystal wafer material.

[0028] The cooling process is as follows: the temperature is lowered to 450℃~500℃ at a rate of 0.1℃ / min~0.5℃ / min and held for 6h~36h; then the temperature is lowered to 380℃~420℃ at a rate of 0.01℃ / min~0.05℃ / min and held for 10h~36h; finally, the temperature is lowered to room temperature at a rate of 0.05℃ / min~0.5℃ / min.

[0029] In the above technical solution, the directional transformation of the red phosphorus gas molecule structure obtained by inducing red phosphorus sublimation with a mineralizing agent is mainly achieved through precise control of two cooling stages. During the cooling process, the red phosphorus gas molecules undergo structural recombination and transformation. After sublimation, the red phosphorus gas molecules undergo nucleation at 450℃~500℃, where the structure is opened and reorganized under the action of the mineralizing agent. After being transported from the source region to the growth region, the slow cooling to 380℃~420℃ is the process of phosphorus molecule crystallization, where the molecular structures rearrange and recombine, transforming the red phosphorus gas structure into a red phosphorus single-crystal structure. Precise programmed cooling first suppresses impurity phases and then promotes the main phase. Through kinetic control, utilizing the difference in nucleation kinetics between the main phase and impurity phases, the generation of multiple phases or defects can be suppressed, improving the single-phase crystal and yield.

[0030] The technical solution of the present invention will be further illustrated below through the following embodiments and comparative examples.

[0031] Example 1 A method for preparing a type II red phosphorus single-crystal wafer material includes the following steps: S1 is a precursor obtained by mixing high-purity red phosphorus as raw material and tin powder as mineralizing agent in a mass ratio of 10:1.

[0032] S2, the precursor is placed in a quartz glass vacuum seal and placed in a dual-temperature zone tube furnace or muffle furnace for reaction. The temperature is increased to 600°C at 5°C / min to completely sublimate the red phosphorus. Then, the temperature is decreased to 460°C at a rate of 0.3°C / min and held at this temperature for 6 hours. The temperature is then decreased to 400°C at a rate of 0.03°C / min and held for 12 hours. Finally, the temperature is slowly decreased to room temperature at a rate of 0.1°C / min to obtain type II red phosphorus single crystal wafer material.

[0033] Example 2 A method for preparing a type II red phosphorus single-crystal wafer material includes the following steps: S1 is a precursor obtained by mixing high-purity red phosphorus as raw material and lead powder as mineralizing agent in a mass ratio of 10:1.

[0034] S2, the precursor is placed in a quartz glass vacuum seal and reacted in a dual-temperature zone tube furnace or muffle furnace. The temperature is increased to 620°C at 1°C / min to completely sublimate the red phosphorus. Then, the temperature is decreased to 450°C at a rate of 0.1°C / min and held there for 36 hours. The temperature is then decreased to 400°C at a rate of 0.01°C / min and held for 36 hours. Finally, the temperature is slowly decreased to room temperature at a rate of 0.05°C / min to obtain type II red phosphorus single crystal wafer material.

[0035] Example 3 S1 is a precursor obtained by mixing high-purity red phosphorus particles as raw material and tin powder as mineralizing agent at a mass ratio of 20:1.

[0036] S2, the precursor is placed in a quartz glass vacuum seal and placed in a dual-temperature zone tube furnace or muffle furnace for reaction. The temperature is increased to 620°C at 3°C / min to completely sublimate the red phosphorus. Then, the temperature is decreased to 500°C at a rate of 0.5°C / min and held at this temperature for 8 hours. The temperature is then decreased to 420°C at a rate of 0.05°C / min and held for 18 hours. Finally, the temperature is slowly decreased to room temperature at a rate of 0.5°C / min to obtain type II red phosphorus single crystal wafer material.

[0037] To further illustrate the technical effects of the present invention, a comparative example is also provided, as follows.

[0038] Comparative Example 1 A method for preparing V-type red phosphorus material includes the following steps: S1 is a precursor obtained by mixing high-purity red phosphorus as raw material and tin powder as mineralizing agent in a mass ratio of 10:1.

[0039] S2, the precursor is placed in a quartz glass vacuum-sealed container and reacted in a dual-temperature zone tube furnace or muffle furnace. The temperature is increased to 620°C at 5°C / min to completely sublimate the red phosphorus. Then, the temperature is decreased to 450°C at a rate of 0.01°C / min and held at this temperature for 36 hours. Next, the temperature is decreased to 400°C at a rate of 0.01°C / min and held for 12 hours. Finally, the temperature is slowly decreased to room temperature at a rate of 0.05°C / min to obtain a dark-colored V-type red phosphorus material, such as... Figure 4 As shown.

[0040] Comparative Example 2 A method for preparing amorphous red phosphorus includes the following steps: S1 is a precursor obtained by mixing high-purity red phosphorus as raw material and lead powder as mineralizing agent in a mass ratio of 10:1. The precursor was placed in a quartz glass vacuum seal and reacted in a dual-temperature zone tube furnace or muffle furnace. The temperature was increased to 620°C at a rate of 5°C / min to completely sublimate the red phosphorus. Then, the temperature was cooled to room temperature at a rate of 1°C / min. Instead of obtaining type II red phosphorus material, amorphous red phosphorus was found attached to the quartz tube wall.

[0041] Figure 1 The images show optical images and product images of the Type II red phosphorus single-crystal material prepared in Example 1 of the present invention. In the image, a is an optical image of the Type II red phosphorus single-crystal material prepared in Example 1 of the present invention. The size of the Type II red phosphorus single-crystal material is about 300 μm. In the image, b is a product image of the prepared Type II red phosphorus single-crystal material. It is an orange-red Type II phosphorus material with no other phosphorus phases present and a yield of up to 98%.

[0042] Figure 2 The crystal structure of the type II red phosphorus single-cell wafer material prepared in Example 1 of this invention is obtained by SCXRD analysis. The results show that the type II red phosphorus structure is composed of ordered single-tube microstructures.

[0043] Figure 3 The image shows the XRD pattern of the type II red phosphorus single-crystal wafer material prepared in Example 1 of this invention. The prepared type II red phosphorus single-crystal wafer material is monoclinic and has a space group of [missing information]. P 21, lattice constant a =13.1±0.1Å, b =34.5±0.1Å, c =18.8±0.1Å, β =109.7±0.1°.

[0044] Figure 4 The images show the product diagram and XRD pattern of the dark-colored V-type red phosphorus material prepared in Comparative Example 1 of this invention. Specifically, a is the product diagram of the dark-colored V-type red phosphorus material prepared in Comparative Example 1 of this invention. Due to the change in the cooling process, the product obtained was not the target product, type II phosphorus material, but a dark-colored product, which is V-type red phosphorus (purple phosphorus); b is the XRD pattern of the dark-colored V-type red phosphorus material prepared in Comparative Example 1 of this invention.

[0045] Figure 5 The product diagram for Comparative Example 2 shows that the amorphous red phosphorus in the quartz tube did not yield the target product after the temperature control program was changed; instead, it remained as amorphous red phosphorus adhering to the wall of the quartz tube.

[0046] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0047] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If these modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a type II red phosphorus single-crystal wafer material, characterized in that, Includes the following steps: Red phosphorus and mineralizing agent are mixed at a mass ratio of 5 to 100:1 to obtain the precursor; The precursor is heated to 580℃~620℃ to sublimate red phosphorus and obtain red phosphorus gas molecules. The red phosphorus gas molecules are then subjected to structural induction by a mineralizing agent and cooled to room temperature by programmed cooling to obtain type II red phosphorus single crystal wafer material. The cooling process is as follows: the temperature is lowered to 450℃~500℃ at a rate of 0.1℃ / min~0.5℃ / min and held for 6h~36h; then the temperature is lowered to 380℃~420℃ at a rate of 0.01℃ / min~0.05℃ / min and held for 10h~36h; finally, the temperature is lowered to room temperature at a rate of 0.05℃ / min~0.5℃ / min.

2. The method for preparing type II red phosphorus single-crystal wafer material according to claim 1, characterized in that, The specific cooling process is as follows: the temperature is lowered to 460℃ at a rate of 0.3℃ / min and held for 6 hours; then it is lowered to 400℃ at a rate of 0.03℃ / min and held for 12 hours; finally, it is lowered to room temperature at a rate of 0.1℃ / min.

3. The method for preparing type II red phosphorus single-crystal wafer material according to claim 1, characterized in that, The heating rate to 580℃~620℃ is 1℃ / min~5℃ / min.

4. The method for preparing type II red phosphorus single-crystal wafer material according to claim 1, characterized in that, The red phosphorus is amorphous red phosphorus with a purity of ≥99.999%.

5. The method for preparing type II red phosphorus single-crystal wafer material according to claim 1, characterized in that, The mineralizing agent is tin powder or lead powder with a purity of ≥99.999%.

6. A type II red phosphorus single-crystal wafer material, characterized in that, It was prepared using the preparation method of type II red phosphorus single crystal wafer material according to any one of claims 1 to 6.

7. The Type II red phosphorus single-crystal wafer material according to claim 6, characterized in that, The type II red phosphorus single crystal wafer material is a monoclinic crystal system, space group [missing information]. P 21, lattice constant a =13.1±0.1Å, b =34.5±0.1Å, c =18.8±0.1Å, β =109.7±0.1°.

8. The Type II red phosphorus single-crystal wafer material according to claim 6, characterized in that, The characteristic size of the type II red phosphorus single crystal wafer material is 100μm~500μm.

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