Polymorphic alpha phase vanadium pentoxide single crystal and controllable preparation method and application thereof

Abstract

This invention relates to multi-morphological α-phase vanadium pentoxide single crystals, their controllable preparation methods, and applications, belonging to the field of functional crystal materials technology. The controllable preparation method includes: providing a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone; placing vanadium pentoxide powder in the high-temperature zone; placing a substrate at the junction of the high-temperature and low-temperature zones; evacuating the dual-temperature zone tube furnace and introducing oxygen to control the reaction pressure; heating and holding the high-temperature and low-temperature zones to evaporate the vanadium pentoxide powder into gaseous molecules, which are then transported to the substrate surface in an oxygen atmosphere for deposition and growth; and naturally cooling to room temperature after the holding period to obtain the target morphology of α-phase vanadium pentoxide single crystals. This invention aims to solve the technical challenge of controlling the preparation of multi-morphological α-phase vanadium pentoxide single crystals from bulk to nanoscale in the same process system, providing a high-quality, multi-morphological single crystal material platform for high-performance electronic and optoelectronic device applications.

Description

Technical Field

[0001] This invention belongs to the field of functional crystal materials technology, specifically relating to multimorphic α-phase vanadium pentoxide single crystals, their controllable preparation methods, and applications. Background Technology

[0002] α-V₂O₅, or α-phase vanadium pentoxide, is the most stable compound in the vanadium oxide system, exhibiting an orthorhombic layered crystal structure. Due to its unique electronic structure and physicochemical properties, α-V₂O₅, as an important functional material, shows broad application prospects in catalysis, battery electrodes, field emitters, transistors, chemical sensors, photoelectric detection, optical waveguides, and high-speed optoelectronic switches.

[0003] Currently, conventional methods for synthesizing α-V₂O₅ mainly include flash evaporation, pulsed laser deposition, magnetron sputtering, atomic layer chemical vapor deposition, and spray pyrolysis. However, these methods typically produce amorphous or polycrystalline thin films, making it difficult to achieve controllable preparation of highly crystalline single-crystal structures. The chemical purification method proposed in 1970 remains the primary means of preparing bulk α-V₂O₅ single crystals, while the preparation of independent α-V₂O₅ nanounit single crystals highly depends on the mechanical exfoliation of bulk crystals. In addition, hydrothermal, solvothermal, chemical vapor deposition (CVD), and physical vapor deposition (PVD) methods have also been reported for the preparation of α-V₂O₅ single crystals. Recent studies have shown that bulk α-V₂O₅ single crystals and inch-scale near-single-crystal thin films can be prepared based on a gas-liquid-solid (VLS) growth mechanism.

[0004] However, existing technologies still have the following shortcomings: First, poor lattice integrity; α-V₂O₅ films prepared by traditional thin film preparation techniques such as flash evaporation and pulsed laser deposition generally suffer from high lattice defect density, easily forming oxygen vacancies, grain boundaries, and other interface scattering centers. These lattice defects significantly degrade the electrical and optical properties of the material, directly limiting its application in precision micro- and nano-devices; Second, the preparation of bulk single crystals is difficult, and the morphology control capability is weak; the preparation of existing bulk α-V₂O₅ single crystals mainly relies on chemical purification methods, which have complex processes and make it difficult to achieve precise control of crystal size and shape; although the gas-liquid-solid growth method can prepare... While bulk α-V₂O₅ single crystals can be prepared, the yield is low, and the process is prone to V=O bond breakage due to high temperatures, leading to structural degradation. Furthermore, achieving thickness reduction in bulk α-V₂O₅ single crystals still heavily relies on mechanical exfoliation, a cumbersome process with poor repeatability, making mass production impossible. Third, physical vapor deposition (PVD) products suffer from significant dimensional limitations. Although existing PVD techniques can prepare α-V₂O₅ single crystals, the crystal thickness is typically on the micrometer scale, while the lateral dimensions are only on the nanometer scale. Moreover, the lack of effective in-situ thickness control methods makes it unsuitable as an ideal platform for studying the intrinsic low-dimensional properties of α-V₂O₅. Fourth, wet chemical methods result in poor dispersibility and separation of products. While hydrothermal and solvothermal methods can synthesize α-V₂O₅ nanosheets, nanoribbons, or nanowires, the products are prone to aggregation, forming cluster structures. This makes effective separation and manipulation of individual nanostructures difficult, hindering the study of the intrinsic properties of independent α-V₂O₅ nanounits.

[0005] In summary, the aforementioned methods generally suffer from problems such as complex processes, low yields, limited crystal morphology, and insufficient dimensional control precision. In particular, they lack a universal, controllable fabrication technology that can achieve various single crystal morphologies, from bulk materials to nanounits and from sheet-like to wire-like forms, within the same process framework. Current technologies cannot achieve large-scale, controllable fabrication of high-quality, multi-dimensional, and multi-morphological α-V₂O₅ single crystals, which has become a key technological bottleneck restricting its further application in high-performance electronic and optoelectronic devices. Summary of the Invention

[0006] The purpose of this invention is to provide multi-morphological α-phase vanadium pentoxide single crystals, their controllable preparation methods, and applications. It aims to achieve the directional, controllable, and large-scale preparation of high-quality, high-crystallinity, and high-purity bulk, micro / nano-scale sheet / ribbon / linear α-phase vanadium pentoxide single crystals in the same process system through precise control of the temperature field and atmosphere conditions in dual-temperature zone physical vapor deposition. This provides an ideal material platform for their property research and high-performance device applications in catalysis, energy, optoelectronics, and other fields.

[0007] On the one hand, the present invention provides a controllable preparation method for multi-morphological α-phase vanadium pentoxide single crystals, employing the following technical solution: A controllable preparation method for multimorphic α-phase vanadium pentoxide single crystals includes the following steps: 1) Provide a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone. Take vanadium pentoxide powder and place it in the high-temperature zone, and take the substrate and place it at the junction of the high-temperature zone and the low-temperature zone. 2) Vacuum treatment is applied to the dual-temperature zone tubular furnace, and oxygen is introduced to control the reaction pressure; 3) The high-temperature zone and the low-temperature zone are heated and held at the temperature to evaporate the vanadium pentoxide powder into gaseous molecules, which are then transported to the substrate surface in an oxygen atmosphere for deposition and growth. After the holding period, the temperature is naturally cooled to room temperature to obtain the α-phase vanadium pentoxide single crystal with the target morphology.

[0008] Preferably, in step 3), the heating rate of the high-temperature zone is 1-25 ℃ / min, the set temperature of the high-temperature zone is 700-1000 ℃, and the holding time of the high-temperature zone is 30-720 min.

[0009] Preferably, in step 3), the heating rate of the low-temperature zone is 1-25 ℃ / min, the set temperature of the low-temperature zone is 200-1000 ℃, and the holding time of the low-temperature zone is 30-800 min.

[0010] Preferably, in step 3), the set temperature of the low-temperature zone is <650 °C, and nanosheet single crystals, nanoribbon single crystals, and / or nanowire single crystals are prepared. The low-temperature zone is set at 650-800 ℃, and micron-sheet single crystals and / or micron-wire single crystals are prepared. The low-temperature zone is set at 800-900 ℃, and a bulk single crystal is prepared.

[0011] Preferably, in step 2), the purity of the oxygen is ≥99.99%, and the flow rate of the oxygen is 50-500 sccm; The reaction pressure is 0.1-10 Torr.

[0012] Preferably, in step 2), the vacuum level after evacuation is ≤0.1 Torr.

[0013] Preferably, in step 1), the purity of the vanadium pentoxide powder is ≥99%, and the dosage of the vanadium pentoxide powder is ≥0.01 g; The substrate includes any one of silicon wafers, silicon oxide wafers, quartz wafers, sapphire wafers, and mica wafers.

[0014] On the one hand, the present invention also provides a multi-morphological α-phase vanadium pentoxide single crystal, employing the following technical solution: A multimorphic α-phase vanadium pentoxide single crystal is prepared by the above-described controllable preparation method. The multimorphic α-phase vanadium pentoxide single crystal includes any one of bulk single crystal, micron sheet single crystal, micron wire single crystal, nanosheet single crystal, nanoribbon single crystal, and nanowire single crystal.

[0015] Preferably, the thickness of the nanosheet single crystal is ≤200 nm, and the lateral dimension is 10-1000 μm; The thickness of the nanoribbon single crystal is ≤100 nm, and the lateral dimension is 1-100 μm; The diameter of the nanowire single crystal is <500 nm, and the length is 10-200 μm; The thickness of the micron-sized single crystal is 1-999 μm, and the lateral dimension is 10-500 μm; The thickness of the micron-wire single crystal is 1-10 μm, the width is 100-1000 nm, and the length is >20 μm.

[0016] Furthermore, this invention also provides an application of multi-morphological α-phase vanadium pentoxide single crystals, employing the following technical solution: Applications of multimorphic α-phase vanadium pentoxide single crystals prepared by the above-described controllable preparation method in the fields of catalysis, battery electrodes, field emitters, transistors, chemical sensors, photodetectors, optical waveguides, or photoelectric switches.

[0017] In summary, the present invention has the following beneficial technical effects: 1. This invention achieves controllable preparation of multiple morphologies of α-V₂O₅ single crystals in the same process system. Employing a dual-temperature zone physical vapor deposition method, by precisely controlling the low-temperature zone temperature to 200-1000 ℃, six typical morphologies of α-V₂O₅ single crystals—bulk single crystals, micron-sheet single crystals, micron-wire single crystals, nanosheet single crystals, nanoribbon single crystals, and nanowire single crystals—are directly grown on the same platform. The controllable preparation method of this invention has a simple process route, requiring no subsequent stripping or template assistance, overcoming the technical bottlenecks of traditional methods where the product morphology is singular and difficult to control on demand. Simultaneously, the separation design of high-temperature evaporation and low-temperature deposition effectively suppresses V=O bond breaking and oxygen vacancy formation, ensuring the crystal lattice integrity and structural stability.

[0018] 2. This invention yields high-quality, large-size α-V₂O₅ single crystal structures. The nanosheet single crystals prepared by this invention have a thickness ≤200 nm and a lateral dimension of 10-1000 μm. The nanoribbon single crystals have a thickness ≤100 nm, a width of 1-5 μm, and a length of tens of micrometers. The nanowire single crystals have a diameter <500 nm and a length of 10-200 μm. Characterization by Raman spectroscopy, XRD, TEM, and SAED confirms that the obtained products are orthorhombic α-V₂O₅ single crystals with pure phase and high crystallinity, complete lattice, and no obvious defects.

[0019] 3. The α-V2O5 single crystals prepared by this invention have excellent dispersibility and can be obtained as independent nano-crystals without ultrasonic treatment or micro-processing. This characteristic avoids the damage to the crystal structure caused by mechanical exfoliation and overcomes the agglomeration problem common in hydrothermal and solvothermal methods, providing an ideal platform for studying the intrinsic properties of α-V2O5 nanounits.

[0020] 4. This invention operates under medium temperature (high temperature range ≤1000 ℃) and low vacuum (0.1-10 Torr) conditions, requires no metal catalysts or organic additives, is compatible with silicon substrate processes, and is suitable for micro-nano device integration; at the same time, physical vapor deposition itself has the advantages of pure process and no chemical waste liquid generation, which meets the requirements of green manufacturing and provides a feasible way for the large-scale preparation of high-quality α-V2O5 single crystals. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the preparation process of multimorphic α-phase vanadium pentoxide single crystals in an embodiment of the present invention; Figure 2 An optical microscope image of the nanosheet single crystal prepared in Example 1 of this invention; Figure 3 Raman spectra of the bulk single crystal, micron sheet single crystal, micron wire single crystal, nano sheet single crystal, nano ribbon single crystal and nano wire single crystal prepared in Examples 1-6 of the present invention; Figure 4 The image shows the XRD spectrum of the nanosheet single crystal prepared in Example 1 of this invention. Figure 5 This is a TEM image of the nanosheet single crystal prepared in Example 1 of the present invention; Figure 6 SAED image of the nanosheet single crystal prepared in Example 1 of this invention; Figure 7 This is an optical microscope image of the bulk single crystal prepared in Example 2 of the present invention; Figure 8 This is an optical microscope image of the micron-sized single crystal prepared in Example 3 of the present invention; Figure 9This is an optical microscope image of the micron-wire single crystal prepared in Example 4 of the present invention; Figure 10 An optical microscope image of the nanoribbon single crystal prepared in Example 5 of this invention; Figure 11 This is an optical microscope image of the nanowire single crystal prepared in Example 6 of the present invention. Detailed Implementation

[0022] The following description is based on Examples 1-6 and the appendix to the instruction manual. Figure 1-11 The present invention will be described in further detail below.

[0023] Example 1 Reference Figure 1 A controllable preparation method for multimorphic α-phase vanadium pentoxide single crystals includes the following steps: S1. Provide a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone. Take 0.5 g of vanadium pentoxide powder (purity 99.99%) and place it in a clean alumina ceramic crucible as an evaporation source, and place it in the center of the high-temperature zone of the dual-temperature zone tube furnace. A silicon wafer with an oxide layer (SiO2 / Si) is used as a substrate and placed at the junction of the high-temperature zone and the low-temperature zone to ensure that the substrate surface is clean. S2. Seal the reaction system and connect a mechanical pump and a vacuum gauge. Start the mechanical pump to evacuate the system, reducing the gas pressure in the reaction system to ≤1.0×10⁻⁶. -2 Torr; oxygen (oxygen flow rate of 300 sccm, oxygen purity of 99.99%) is introduced to maintain the reaction pressure at 2.09 Torr; S3. Set the heating program for the high temperature zone and the low temperature zone. The high temperature zone is heated to 960 ℃ at a rate of 10.7 ℃ / min and held for 360 min. The low temperature zone is heated to 610 ℃ at a rate of 20.3 ℃ / min and held for 420 min. During this process, V2O5 gaseous molecules are deposited and epitaxially grown on the substrate surface in the reaction zone; S4. After the heat preservation is completed, stop heating and allow the reaction system to cool naturally to room temperature. Close the oxygen inlet valve and introduce air to restore the reaction system to normal pressure. Take out the substrate, and uniformly distributed nanosheet single crystals can be seen on the surface.

[0024] Reference Figure 2 The α-V2O5 nanosheet single crystals prepared in Example 1 of this invention exhibit a rectangular sheet structure with smooth edges and regular shape. Its lateral dimensions (length / width) are on the order of micrometers (10-1000 μm) and its thickness is on the order of nanometers (≤200nm), indicating that this method can achieve the direct growth of nanosheets with large lateral dimensions, uniform thickness and regular shape.

[0025] Reference Figure 3 and Figure 4 All characteristic peaks in the Raman spectrum correspond to the standard spectrum of orthorhombic α-V₂O₅, and no impurity peaks appear, confirming that the product prepared in Example 1 of this invention is a single-phase α-V₂O₅. The (001) crystal plane diffraction peaks in the X-ray diffraction pattern are significant, indicating that the crystal preferentially grows along the c-axis to form a layered stacked structure; all diffraction peaks can be indexed as orthorhombic α-V₂O₅ (JCPDS No. 41-1426), indicating good crystallinity.

[0026] Reference Figure 5 and Figure 6 In transmission electron microscopy, the α-V2O5 nanosheets prepared in Example 1 of the present invention show clear lattice fringes corresponding to the (0, 0, 1) plane of the crystal; the selected area electron diffraction pattern shows sharp diffraction spots, further confirming that the product prepared in Example 1 of the present invention is a single crystal structure with consistent orientation and no defects such as grain boundaries or twins.

[0027] In summary, Example 1 of this invention successfully prepared α-V₂O₅ nanosheet single crystals with high crystal quality, regular morphology, large lateral dimensions, and a thickness only on the nanometer scale by precisely controlling the high-temperature region (960 ℃), the low-temperature region (610 ℃), the reaction pressure (2.09 Torr), and the growth time. Characterization results show that the grown nanosheet single crystals have the characteristics of single phase and high crystallinity. This preparation method has high yield and can obtain independent and dispersed α-V₂O₅ nanosheet single crystals without subsequent exfoliation, providing an ideal material sample for low-dimensional property research and nanodevice integration.

[0028] Example 2 A controllable preparation method for multimorphic α-phase vanadium pentoxide single crystals includes the following steps: S1. Provide a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone. Take 0.5 g of vanadium pentoxide powder (purity 99.99%) and place it in a clean alumina ceramic crucible as an evaporation source, and place it in the center of the high-temperature zone of the dual-temperature zone tube furnace. A silicon wafer with an oxide layer (SiO2 / Si) is used as a substrate and placed at the junction of the high-temperature zone and the low-temperature zone to ensure that the substrate surface is clean. S2. Seal the reaction system and connect a mechanical pump and a vacuum gauge. Start the mechanical pump to evacuate the system, reducing the gas pressure in the reaction system to ≤1.0×10⁻⁶. -2 Torr; Introduce oxygen (oxygen flow rate 300 sccm, oxygen purity 99.99%) to maintain a stable reaction pressure of 2.1 Torr; S3. Set the heating program for the high temperature zone and the low temperature zone. The high temperature zone is heated to 960 ℃ at a rate of 10.7 ℃ / min and held for 360 min. The low temperature zone is heated to 860 ℃ at a rate of 10.8 ℃ / min and held for 370 min. During this process, V2O5 gaseous molecules are deposited and epitaxially grown on the substrate surface in the reaction zone; S4. After the heat preservation is completed, stop heating and allow the reaction system to cool naturally to room temperature. Close the oxygen inlet valve, introduce air to restore the reaction system to normal pressure, remove the substrate, and uniformly distributed bulk single crystals can be seen on the surface.

[0029] Reference Figure 7 The product crystal prepared in Example 2 of this invention exhibits an irregular blocky morphology, with its lateral dimensions (length / width) ranging from hundreds of micrometers to millimeters. Due to the large crystal thickness, it shows low light transmittance under an optical microscope, and its overall color is dark, indicating that the product is a typical three-dimensional block material.

[0030] Reference Figure 3 All characteristic peaks in the Raman spectrum correspond to the standard spectrum of orthorhombic α-V2O5, and no impurity peaks appear, confirming that the product is a single-phase α-V2O5.

[0031] Example 3 A controllable preparation method for multimorphic α-phase vanadium pentoxide single crystals includes the following steps: S1. Provide a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone. Take 0.5 g of vanadium pentoxide powder (purity 99.99%) and place it in a clean alumina ceramic crucible as an evaporation source, and place it in the center of the high-temperature zone of the dual-temperature zone tube furnace. A silicon wafer with an oxide layer (SiO2 / Si) is used as a substrate and placed at the junction of the high-temperature zone and the low-temperature zone to ensure that the substrate surface is clean. S2. Seal the reaction system and connect a mechanical pump and a vacuum gauge. Start the mechanical pump to evacuate the system, reducing the gas pressure in the reaction system to ≤1.0×10⁻⁶. -2 Torr; Introduce oxygen (oxygen flow rate 300 sccm, oxygen purity 99.99%) to maintain a stable reaction pressure of 2.12 Torr; S3. Set the heating program for the high temperature zone and the low temperature zone. The high temperature zone is heated to 960 ℃ at a rate of 10.7 ℃ / min and held for 360 min. The low temperature zone is heated to 760 ℃ at a rate of 9.5 ℃ / min and held for 370 min. During this process, V2O5 gaseous molecules are deposited and epitaxially grown on the substrate surface in the reaction zone; S4. After the heat preservation is completed, stop heating and allow the reaction system to cool naturally to room temperature. Close the oxygen inlet valve, introduce air to restore the reaction system to normal pressure, remove the substrate, and uniformly distributed micron-sized single crystal flakes can be seen on the surface.

[0032] Reference Figure 8 The product crystal prepared in Example 3 of this invention exhibits an irregular lamellar structure with overlapping growth between the lamellar layers. The lateral dimensions (length / width) of the above-mentioned micron-sized single crystals are distributed in the range of 10-500 μm, and the thickness is on the order of micrometers (approximately 1-500 μm).

[0033] Reference Figure 3 All characteristic peaks in the Raman spectrum correspond to the standard spectrum of orthorhombic α-V2O5, and no impurity peaks appear, confirming that the product is a single-phase α-V2O5.

[0034] Example 4 A controllable preparation method for multimorphic α-phase vanadium pentoxide single crystals includes the following steps: S1. Provide a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone. Take 0.5 g of vanadium pentoxide powder (purity 99.99%) and place it in a clean alumina ceramic crucible as an evaporation source, and place it in the center of the high-temperature zone of the dual-temperature zone tube furnace. A silicon wafer with an oxide layer (SiO2 / Si) is used as a substrate and placed at the junction of the high-temperature zone and the low-temperature zone to ensure that the substrate surface is clean. S2. Seal the reaction system and connect a mechanical pump and a vacuum gauge. Start the mechanical pump to evacuate the system, reducing the gas pressure in the reaction system to ≤1.0×10⁻⁶. -2 Torr; Introduce oxygen (oxygen flow rate 300 sccm, oxygen purity 99.99%) to maintain a stable reaction pressure of 2.12 Torr; S3. Set the heating program for the high temperature zone and the low temperature zone. The high temperature zone is heated to 960 ℃ at a rate of 10.7 ℃ / min and held for 360 min. The low temperature zone is heated to 660 ℃ at a rate of 8.3 ℃ / min and held for 370 min. During this process, V2O5 gaseous molecules are deposited and epitaxially grown on the substrate surface in the reaction zone; S4. After the heat preservation is completed, stop heating and allow the reaction system to cool naturally to room temperature. Close the oxygen inlet valve and introduce air to restore the reaction system to normal pressure. Take out the substrate, and uniformly distributed micron-line single crystals can be seen on the surface.

[0035] Reference Figure 9The product crystal prepared in Example 4 of the present invention exhibits an irregular linear structure with obvious overlapping growth characteristics between crystals. The length of the above-mentioned micron-line single crystal is distributed in the range of micrometers to millimeters (>20 μm), the thickness is about 1-10 μm, and the width is only in the range of nanometers (100-1000 nm).

[0036] Reference Figure 3 All characteristic peaks in the Raman spectrum correspond to the standard spectrum of orthorhombic α-V2O5, and no impurity peaks appear, confirming that the product is a single-phase α-V2O5.

[0037] Example 5 A controllable preparation method for multimorphic α-phase vanadium pentoxide single crystals includes the following steps: S1. Provide a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone. Take 0.5 g of vanadium pentoxide powder (purity 99.99%) and place it in a clean alumina ceramic crucible as an evaporation source, and place it in the center of the high-temperature zone of the dual-temperature zone tube furnace. A silicon wafer with an oxide layer (SiO2 / Si) is used as a substrate and placed at the junction of the high-temperature zone and the low-temperature zone to ensure that the substrate surface is clean. S2. Seal the reaction system and connect a mechanical pump and a vacuum gauge. Start the mechanical pump to evacuate the system, reducing the gas pressure in the reaction system to ≤1.0×10⁻⁶. -2 Torr; Introduce oxygen (oxygen flow rate 300 sccm, oxygen purity 99.99%) to maintain a stable reaction pressure of 2.1 Torr; S3. Set the heating program for the high temperature zone and the low temperature zone. The high temperature zone is heated to 960 ℃ at a rate of 10.7 ℃ / min and held for 360 min. The low temperature zone is heated to 560 ℃ at a rate of 18.7 ℃ / min and held for 420 min. During this process, V2O5 gaseous molecules are deposited and epitaxially grown on the substrate surface in the reaction zone; S4. After the heat preservation is completed, stop heating and allow the reaction system to cool naturally to room temperature. Close the oxygen inlet valve and introduce air to restore the reaction system to normal pressure. Take out the substrate, and uniformly distributed nanoribbon single crystals can be seen on the surface.

[0038] Reference Figure 10 The product crystal prepared in Example 5 of the present invention exhibits a ribbon-like structure with clear edges and a smooth surface, and has obvious anisotropic growth characteristics. The length of the above-mentioned nanoribbon single crystal is 10-100 μm, the width is 1-5 μm, and the thickness is ≤100 nm. The nanoribbon single crystal grows uniformly along the axial direction, with a smooth surface, clear edges, and no obvious breakage or agglomeration.

[0039] Reference Figure 3All characteristic peaks in the Raman spectrum correspond to the standard spectrum of orthorhombic α-V2O5, and no impurity peaks appear, confirming that the product is a single-phase α-V2O5.

[0040] Example 6 A controllable preparation method for multimorphic α-phase vanadium pentoxide single crystals includes the following steps: S1. Provide a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone. Take 0.5 g of vanadium pentoxide powder (purity 99.99%) and place it in a clean alumina ceramic crucible as an evaporation source, and place it in the center of the high-temperature zone of the dual-temperature zone tube furnace. A silicon wafer with an oxide layer (SiO2 / Si) is used as a substrate and placed at the junction of the high-temperature zone and the low-temperature zone to ensure that the substrate surface is clean. S2. Seal the reaction system and connect a mechanical pump and a vacuum gauge. Start the mechanical pump to evacuate the system, reducing the gas pressure in the reaction system to ≤1.0×10⁻⁶. -2 Torr; Introduce oxygen (oxygen flow rate 300 sccm, oxygen purity 99.99%) to maintain a stable reaction pressure of 2.1 Torr; S3. Set the heating program for the high temperature zone and the low temperature zone. The high temperature zone is heated to 960 ℃ at a rate of 10.7 ℃ / min and held for 360 min. The low temperature zone is heated to 360 ℃ at a rate of 12 ℃ / min and held for 420 min. During this process, V2O5 gaseous molecules are deposited and epitaxially grown on the substrate surface in the reaction zone; S4. After the heat preservation is completed, stop heating and allow the reaction system to cool naturally to room temperature. Close the oxygen inlet valve, introduce air to restore the reaction system to normal pressure, remove the substrate, and uniformly distributed nanowire single crystals can be seen on the surface.

[0041] Reference Figure 11 The product crystal prepared in Example 6 of the present invention exhibits a typical one-dimensional linear structure with a high aspect ratio. The length of the above-mentioned nanowire single crystal is usually 10-200 μm, the diameter is on the nanometer scale (<500 nm), and the surface is smooth with clear edges.

[0042] Reference Figure 3 All characteristic peaks in the Raman spectrum correspond to the standard spectrum of orthorhombic α-V2O5, and no impurity peaks appear, confirming that the product is a single-phase α-V2O5.

[0043] In summary, the product crystals prepared in Examples 1-6 of this invention can be applied in the fields of catalysis, battery electrodes, field emitters, transistors, chemical sensors, photodetectors, optical waveguides, or photoelectric switches.

[0044] The embodiments shown in this specification are only used to illustrate the technical solutions of the present invention and are intended to help those skilled in the art understand the principles and advantages of the present invention. They do not constitute a limitation on the scope of protection of the present invention. Although the present invention has been specifically described, those skilled in the art can still make any modifications, equivalent substitutions or other reasonable variations to the implementation methods without departing from the spirit and scope of the present invention. All equivalent technical solutions resulting therefrom should be considered within the scope of protection of this patent.

Claims

1. A controllable preparation method for multimorphic α-phase vanadium pentoxide single crystals, characterized in that, Includes the following steps: 1) Provide a dual-temperature zone tube furnace containing a high-temperature zone and a low-temperature zone. Take vanadium pentoxide powder and place it in the high-temperature zone, and take the substrate and place it at the junction of the high-temperature zone and the low-temperature zone. 2) Vacuum treatment is applied to the dual-temperature zone tubular furnace, and oxygen is introduced to control the reaction pressure; 3) The high-temperature zone and the low-temperature zone are heated and held at the temperature to evaporate the vanadium pentoxide powder into gaseous molecules, which are then transported to the substrate surface in an oxygen atmosphere for deposition and growth. After the holding period, the temperature is naturally cooled to room temperature to obtain the α-phase vanadium pentoxide single crystal with the target morphology.

2. The controllable preparation method of multimorphic α-phase vanadium pentoxide single crystals according to claim 1, characterized in that, In step 3), the heating rate of the high-temperature zone is 1-25 ℃ / min, the set temperature of the high-temperature zone is 700-1000 ℃, and the holding time of the high-temperature zone is 30-720 min.

3. The controllable preparation method of multimorphic α-phase vanadium pentoxide single crystals according to claim 1, characterized in that, In step 3), the heating rate of the low-temperature zone is 1-25 ℃ / min, the set temperature of the low-temperature zone is 200-1000 ℃, and the holding time of the low-temperature zone is 30-800 min.

4. The controllable preparation method of multimorphic α-phase vanadium pentoxide single crystals according to claim 3, characterized in that, In step 3), the set temperature of the low-temperature zone is <650 ℃, and nanosheet single crystals, nanoribbon single crystals and / or nanowire single crystals are prepared. The low-temperature zone is set at 650-800 ℃, and micron-sheet single crystals and / or micron-wire single crystals are prepared. The low-temperature zone is set at 800-900 ℃, and a bulk single crystal is prepared.

5. The controllable preparation method of multimorphic α-phase vanadium pentoxide single crystals according to claim 1, characterized in that, In step 2), the purity of the oxygen is ≥99.99%, and the flow rate of the oxygen is 50-500 sccm; The reaction pressure is 0.1-10 Torr.

6. The controllable preparation method of multimorphic α-phase vanadium pentoxide single crystals according to claim 1, characterized in that, In step 2), the vacuum level after evacuation is ≤0.1 Torr.

7. The controllable preparation method of multimorphic α-phase vanadium pentoxide single crystals according to claim 1, characterized in that, In step 1), the purity of the vanadium pentoxide powder is ≥99%, and the dosage of the vanadium pentoxide powder is ≥0.01 g; The substrate includes any one of silicon wafers, silicon oxide wafers, quartz wafers, sapphire wafers, and mica wafers.

8. A multimorphic α-phase vanadium pentoxide single crystal prepared by the controllable preparation method according to any one of claims 1-7, characterized in that, The multimorphic α-phase vanadium pentoxide single crystals include any one of bulk single crystals, micron-sheet single crystals, micron-wire single crystals, nanosheet single crystals, nanoribbon single crystals, and nanowire single crystals.

9. The multimorphic α-phase vanadium pentoxide single crystal according to claim 8, characterized in that, The thickness of the nanosheet single crystal is ≤200 nm, and the lateral dimension is 10-1000 μm; The thickness of the nanoribbon single crystal is ≤100 nm, and the lateral dimension is 1-100 μm; The diameter of the nanowire single crystal is <500 nm, and the length is 10-200 μm; The thickness of the micron-sized single crystal is 1-999 μm, and the lateral dimension is 10-500 μm; The thickness of the micron-wire single crystal is 1-10 μm, the width is 100-1000 nm, and the length is >20 μm.

10. An application of a multimorphic α-phase vanadium pentoxide single crystal prepared by the controllable preparation method as described in any one of claims 1-7 in the fields of catalysis, battery electrodes, field emitters, transistors, chemical sensors, photodetectors, optical waveguides, or photoelectric switches.

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