Diverse alpha-phase tellurium oxide nano material as well as preparation method and application thereof

Abstract

The invention discloses a diversified alpha-phase tellurium oxide nano material as well as a preparation method and application thereof. The nano material is an alpha-phase tellurium oxide nano sheet, nano wire or nano broken line deposited on the surface of a substrate through a chemical vapor deposition method. The preparation method comprises the following steps: paving tellurium powder at the front end of a quartz boat, and placing a substrate above the powder; placing the quartz boat in a high-temperature rapid annealing furnace, carrying out a high-temperature reaction for 1-4 h in an oxygen atmosphere, carrying out a thermal evaporation process on the Te powder to convert the Te powder into gaseous Te molecules, and then carrying out a reaction on the gaseous Te molecules and oxygen to generate gaseous TeO2 molecules; and after the reaction is finished, cooling to room temperature, condensing TeO2 molecules on the surface of the substrate, growing various alpha-phase tellurium oxide nano structures on the substrate through CVD, and promoting the formation of TeO2 seed crystals by taking the substrate as a nucleation site. The obtained nano material has the characteristics of uniform size, regular shape, smooth surface and clear boundary, is firmly combined with the substrate, and has excellent stability; wide application prospects are shown in the fields of electronics, optics, energy industries and the like.

Description

Technical Field

[0001] The present invention belongs to the field of novel electronic information materials, and specifically relates to a variety of α-phase tellurium oxide nanomaterials and a preparation method and application thereof. Background Art

[0002] The morphology of a material has a significant impact on its physical and chemical properties. Especially for nanostructured semiconductor materials, their size and shape are the key factors that determine their unique properties. Therefore, achieving precise control over the size and morphology of semiconductor nanocrystals has become a frontier and hot topic in scientific research in recent years. Due to its unique physical and chemical properties, α-TeO2 nanostructures have good application prospects in gas sensors, dosimeters, modulators, laser devices, optical storage materials and deflectors. The controllable preparation of α-TeO2 nanostructures has always been a challenge. Low-dimensional oxide semiconductor nanostructures, such as nanowires, nanofolds and nanosheets, show great potential in nanotechnology applications due to their unique physical and chemical properties. The preparation methods of α-TeO2 nanostructures mainly include thermal evaporation, microwave-assisted aerosol method, physical vapor deposition method, molecular beam epitaxy growth method and solution synthesis method. The preparation process of the synthesized α-TeO2 nanostructure is complex and requires specific equipment and technology. The research on its growth mechanism is relatively insufficient and the monitoring of the growth process needs to be improved. The size and morphology control is relatively difficult.

[0003] Therefore, it is necessary to develop a simple, efficient and low-cost method for preparing α-phase tellurium oxide nanostructures. Future development will focus on improving its photoelectric response in the short-wave band and broadening its application in highly integrated chips, biomedicine, laser technology, transparent electronic devices and display technology. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a variety of α-phase tellurium oxide nanomaterials and their preparation methods and uses. The α-TeO2 nanomaterials have high quality and high crystallinity, uniform size, regular shape, smooth surface and clear boundaries; and the preparation process is simple, low cost, short time consumption and environmentally friendly.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: A variety of α-phase tellurium oxide nanomaterials, which are α-phase tellurium oxide nanosheets, nanowires or nanofolds deposited on the surface of a substrate by chemical vapor deposition, and have the characteristics of uniform size, regular shape, smooth surface and clear boundaries.

[0006] The length of the nanosheet is 5-20 µm and the width is 5 µm; the length of the nanowire is 10-100 µm and the diameter is 100 nm-1 nm µm; the angle of the nanofold is 90°-150° and the length is 10-100 µm.

[0007] The method for preparing the above-mentioned diverse α-phase tellurium oxide nanomaterials comprises the following steps: Step (1) Place tellurium powder flatly on the front end of a quartz boat, and place a clean silicon wafer as a substrate 1 to 7.5 mm above the powder; The particle size of the tellurium powder is 30 mesh.

[0008] Step (2) placing the entire step (1) in the center of a high-temperature rapid annealing furnace, reacting at high temperature for 1 to 4 hours in an oxygen atmosphere, wherein the Te powder undergoes a thermal evaporation process and is converted into gaseous Te molecules, which then react with oxygen to generate gaseous TeO2 molecules; Specifically, the reaction conditions are: 20~80 sccm, 460~560℃, 0~0.15 Mpa and greater than 0 Mpa for 1~4h; nanowires and nanofolds are prepared in turn after reacting for 1h~4h, and the length of the nanomaterials gradually increases with the extension of the reaction time; the reaction pressure is increased to 0.15 Mpa to obtain nanosheets, and as the pressure increases, the nanowires are transformed into nanosheet structures with a smaller surface-to-volume ratio.

[0009] After step (3) is completed, the temperature is returned to room temperature, and TeO2 molecules condense on the surface of the substrate. Various α-phase tellurium oxide nanostructures are grown on the substrate by CVD. The substrate acts as a nucleation site, promoting the formation of TeO2 seed crystals.

[0010] The above-mentioned various α-phase tellurium oxide nanomaterials are used in the field of optoelectronic devices.

[0011] Beneficial effects of the present invention: 1) The present invention uses tellurium powder as a source material and prepares α-phase tellurium oxide nanomaterials after high-temperature annealing. The nanomaterials include: nanosheets (length 5-20 µm and width 5 µm), nanowires or fold lines (length 10-100 µm, fold line angle 90°-150°), which have uniform size, regular shape, smooth surface, clear boundary, excellent crystallization performance and strong stability.

[0012] 2) The nanomaterial prepared by the present invention has good nanomorphology. At the same time, the preparation process of the tellurium oxide nanostructure is simple, cost-effective, and the raw materials are easily available and environmentally friendly. These characteristics make it have good application prospects in the fields of gas sensors, dosimeters, modulators, laser devices, optical storage materials and deflectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The scanning electron microscope images of α-phase tellurium oxide nanosheets prepared at different reaction times in Example 1; (a) in (1) is a reaction time of 1 h, (b) is a reaction time of 2 h, and (c) is a reaction time of 4 h; (2) is an enlarged view of (c); Figure 2 This is the Raman spectrum of the α-phase tellurium oxide nanosheets prepared in Example 1 when the reaction time is 4 hours; Figure 3 XRD patterns of alpha tellurium oxide nanosheets, wires, and broken wire materials prepared for Examples 1, 2, and 3; Figure 4 The scanning electron microscope images of α-phase tellurium oxide nanomaterials prepared at different oxygen pressures in Example 2; (a) 0 Mpa, (b) 0.05 Mpa, (c) 0.1 Mpa, (d) 0.15 Mpa; Figure 5 The scanning electron micrographs of α-phase tellurium oxide nanowires prepared at different reaction temperatures in Example 3; (a) 460°C reaction for 1 h; (b) 460°C reaction for 4 h; Figure 6 This is the XRD spectrum of the α-tellurium oxide nanowire material prepared in Example 4. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0015] To clearly illustrate the technical solution of the present invention, in the following embodiments, the tellurium powder used has a particle size of 30 mesh and a purity of 99.997%; the quartz boat used has a size of 50 mm in length, 15 mm in width, and 7.5 mm in height; and the silicon substrate used has a length of 15 mm and a width of 12 mm. However, this is not limited thereto.

[0016] The method for preparing α-phase tellurium oxide nanosheets comprises the following steps: (1) Place 50 mg of tellurium powder flat on one end of a quartz boat, then place a clean silicon substrate over the tellurium powder without touching it (the silicon substrate should be 1-10 mm away from the top of the tellurium powder). (2) The quartz boat was sent to the center of a high-temperature vacuum annealing furnace, and the vacuum was evacuated and oxygen was introduced at an oxygen flow rate of 80 sccm. In an oxygen atmosphere, the reaction was carried out at 460°C and 0.15 MPa for different time periods (1 h, 2 h, 4 h, and 6 h) to investigate the effect of reaction time on the results. After the reaction was completed, the temperature was returned to room temperature and the device was taken out. The product obtained on the silicon substrate was α-phase tellurium oxide nanosheets. Under high temperature conditions, the Te powder undergoes a thermal evaporation process and is converted into gaseous Te molecules. These molecules then react with the surrounding oxygen (O2) to generate gaseous TeO2 molecules. In the next step, the TeO2 molecules condense on the substrate surface, and the substrate acts as a nucleation site to promote the formation of TeO2 seed crystals. Therefore, according to the deposition conditions, more TeO2 molecules can be continuously aggregated through the growth mechanism of chemical vapor deposition (CVD), and finally form a TeO2 structure that meets the expected shape.

[0017] Figure 1 (a) α-phase tellurium oxide nanosheets prepared with a reaction time of 1 h; Figure 1 (b) α-phase tellurium oxide nanosheet material prepared with a reaction time of 2 h; Figure 1 (c) is the α-phase tellurium oxide nanosheet material prepared with a reaction time of 4 h. It can be seen that when the reaction time is less than 1 h, the reaction time is short, the prepared α-phase tellurium oxide nanosheets have poor crystallinity, incomplete structure, and many defects on the grain edges; when the reaction time is greater than 6 h, the surface roughness increases, and the nanosheets present complex morphologies such as layers, making the originally dispersed nanosheets become more dense and even forming larger agglomerates. Moreover, as the reaction time increases, the length of the nanosheets gradually increases. α-phase tellurium oxide nanosheets prepared with a reaction time of 4 h ( Figure 1 (c)) exhibits high quality characteristics that are critical to its performance in high-performance nanomaterial applications. It has well-defined edges, high dimensional consistency, orderly morphology, smooth surface, and no significant defects or impurities, nor are there any unclear or broken areas. Therefore, the final reaction time was 4h.

[0018] Figure 2 The Raman spectrum of the α-phase tellurium oxide nanosheet prepared in Example 1 with a reaction time of 4 h. The obtained α-TeO2 has a tetragonal crystal structure with a P41212 space group. Its crystal structure has a specific symmetry and can be described as a vibration mode with 8 E modes, 4 A1 modes, 4 A2 modes, 5 B1 modes and 4 B2 modes. According to the Raman spectrum results, the α-phase tellurium oxide has a high spectral density at 110 cm −1 、393 cm −1 and 648 cm −1 The characteristic vibration mode at 172 cm −1A sharp B1 bending mode can be observed at 592 cm −1 A Raman peak appears near the A1 vibration mode. The appearance of sharp Raman peaks clearly indicates that the TeO2 nanosheets have high crystallinity.

[0019] Figure 3 This is the XRD spectrum of the α-phase tellurium oxide nanosheets prepared in Example 1 with a reaction time of 4 h. It can be seen that the nanosheets show a preferential orientation along the (102) direction, confirming the crystal structure of the α-TeO2 lattice.

[0020] Based on the process parameter of 4h reaction time in Example 1, the oxygen pressure of α-tellurium oxide nanomaterial growth was adjusted to investigate its influence on the results, specifically 0 Mpa, 0.05 Mpa, 0.1 Mpa, and 0.15 Mpa. The characterization diagrams of the obtained material structures correspond to Figure 4 (a) Figure 4 (b) Figure 4 (c) Figure 4 (d) It can be seen that within the pressure range of 0-0.15 MPa, as the oxygen pressure increases, the nanowires transform into nanosheets with a smaller surface-to-volume ratio.

[0021] A method for preparing α-phase tellurium oxide nanowires comprises the following steps: (1) Place 50 mg of tellurium powder flat on one end of a quartz boat, then place a clean silicon substrate over the tellurium powder without touching it (the silicon substrate should be 1-5 mm away from the top of the tellurium powder). (2) The quartz boat was placed in the center of a high-temperature vacuum annealing furnace, and the vacuum was evacuated and oxygen was introduced at an oxygen flow rate of 80 sccm. The reaction was carried out at different reaction temperatures (specifically 400°C, 420°C, 440°C, 460°C, 480°C, and 500°C) and 0 MPa for 1 h in an oxygen atmosphere. After the reaction was completed, the reaction was cooled to room temperature and the device was taken out. The product obtained on the silicon substrate was α-phase tellurium oxide nanowires. Figure 5 (a) It can be seen that the α-tellurium oxide nanowires obtained by reacting at a reaction temperature of 460℃ for 1h have clear boundaries, uniform size, regular shape, smooth surface, and no obvious defects or impurities. Figure 2 It can be seen that the Raman peaks observed in the α-tellurium oxide nanowire material prepared under this condition perform well and are consistent with the literature on the α-tellurium oxide crystal phase; Figure 3 It can be seen that high-intensity, sharp diffraction peaks usually indicate that the prepared α-tellurium oxide nanosheets have good crystallinity. Figure 5 (b) The size distribution is uniform, the boundaries are clear, the surface is smooth, and the nano-folds are intact without breaks, showing good mechanical strength and structural stability. Figure 6It can be seen that the materials prepared at 400℃, 420℃, and 440℃ have poor crystallinity, which can confirm the presence of tellurium in the sample. The materials prepared at 460℃, 480℃, and 500℃ do not contain tellurium and are completely oxidized to tellurium oxide, and the product has good crystallinity. Secondly, all peaks observed in the XRD spectrum of the prepared TeO2 sample are assumed to be the tetragonal (α-phase) crystal structure of tellurium oxide.

[0022] Based on the process parameters of Example 3, the oxygen gas flow rate was adjusted to investigate its effect on the performance of the nanowires, specifically 0 sccm, 20 sccm, 40 sccm, and 80 sccm. The material prepared with a gas flow rate of 40 sccm not only has uniform size and shape, a smooth surface, clear boundaries, but also has strong crystallization performance and stability. When the gas flow rate is lower than 40 sccm, the growth rate of the nanowire will decrease, because the insufficient supply of the reaction gas causes the rate at which Te molecules reach the growth surface to slow down, and the active species to decrease. Its structure will become loose, and since gas flow is essential for dispersing and homogenizing the growth precursors, too low a flow rate may cause gaseous Te molecules to accumulate in local areas, forming uneven growth. In addition, the morphology of the α-tellurium oxide nanowire becomes irregular, because gas flow is essential for maintaining temperature and concentration uniformity during the growth process, and too low a flow rate may cause overheating in local areas or uneven Te concentration in the environment. When the gas flow rate is higher than 80 sccm, it causes changes in the morphology of the nanowire, such as from a regular sheet structure to an irregular or porous structure. Therefore, in order to obtain high-quality nanostructured materials, precise control of the gas flow rate is crucial to ensure the uniformity and continuity of the growth process.

[0023] It should be understood that the above is only a preferred embodiment of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, but these improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A diverse α-phase tellurium oxide nanomaterial, characterized in that: The nanomaterial is α-phase tellurium oxide nanosheets, nanowires or nanofolds deposited on the surface of a substrate by chemical vapor deposition, and has the characteristics of uniform size, regular shape, smooth surface and clear boundaries.

2. The diverse α-phase tellurium oxide nanomaterial according to claim 1, characterized in that: The nanosheet has a length of 5 to 20 µm and a width of 5 µm; The length of the nanowires is 10~100 µm, and the diameter is 100 nm~1 nm µm; The angle of the nano-fold line is 90°~150° and the length is 10~100 µm.

3. The method for preparing the diverse α-phase tellurium oxide nanomaterials according to claim 1, characterized in that: The steps include: Step (1) Place tellurium powder flatly on the front end of a quartz boat, and place a clean silicon wafer as a substrate 1 to 7.5 mm above the powder; Step (2) placing the entire step (1) in the center of a high-temperature rapid annealing furnace, reacting at high temperature for 1 to 4 hours in an oxygen atmosphere, wherein the Te powder undergoes a thermal evaporation process and is converted into gaseous Te molecules, which then react with oxygen to generate gaseous TeO2 molecules; After step (3) is completed, the substrate is cooled to room temperature, and TeO2 molecules condense on the substrate surface. Various α-phase tellurium oxide nanostructures are grown on the substrate by CVD. The substrate acts as a nucleation site, promoting the formation of TeO2 seed crystals.

4. The method for preparing the diverse α-phase tellurium oxide nanomaterials according to claim 3, characterized in that: The reaction conditions of step (2) are: 20-80 sccm, 460-560°C, 0-0.15 Mpa and greater than 0 Mpa for 1-4 h; nanowires and nanofolds are prepared in turn after reacting for 1 h to 4 h, and as the reaction time increases, the length of the nanomaterial gradually increases; the reaction pressure is increased to 0.15 Mpa to obtain nanosheets, and as the pressure increases, the nanowires are transformed into nanosheet structures with a smaller surface-to-volume ratio.

5. The method for preparing the diverse α-phase tellurium oxide nanomaterials according to claim 3, characterized in that: In step (1), the particle size of the tellurium powder is 30-50 mesh.

6. Use of the diverse α-phase tellurium oxide nanomaterial obtained according to claim 1 in the field of optoelectronic devices.

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