Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Carbothermal reduction and the preparation of silicon carbide nanowires its performance

Author LuoXiaoGang
Tutor MaWenHui
School Kunming University of Science and Technology
Course Non-ferrous metallurgy
Keywords SiC nanowires Carbothermal reduction Photoluminescence Field Emission Photocatalytic Degradation
CLC TB383.1
Type Master's thesis
Year 2010
Downloads 130
Quotes 2
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Third generation wide band gap semiconductor SiC material with its large band gap, a high melting point and hardness, high thermal conductivity, high critical breakdown field, high saturated electron mobility, resistance to radiation and strong as well as good mechanical properties and other features, is an ideal material for production of high-power, high-frequency, low-power, high temperature resistant and anti-radiation devices and by the extensive attention. Recent studies have shown that compared with bulk SiC material has excellent optical, electrical, and mechanical properties of SiC nanowires, metal matrix, ceramic matrix and polymer matrix reinforced composite materials, preparation of light-emitting diodes, power transistors and other electronic and optoelectronic nanoscale devices, field emission cathode material, photocatalytic hydrogen storage and self-cleaning films and many other fields have a wide application prospect. Preparation and Properties of SiC nanowires therefore of great significance. This article by carbothermal reduction Si02 SiC nanowires prepared under the atmospheric pressure metal catalysts conditions, combined with the X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray energy dispersive (EDS), transmission electron microscopy (TEM) analysis of test methods, analysis of the composition, morphology and microstructure of SiC nanowires. Prepared SiC nanowires process parameters affect the carbothermal reduction reaction process thermodynamics and SiC nanowire growth mechanism. Finally, the luminescent properties of SiC nanowires prepared, field emission properties and photocatalytic properties studied. Paper mainly includes the following aspects: (1) under atmospheric pressure, to charcoal as the carbon source, C, and Si02 molar ratio of 3, the reaction for 20 minutes under the reaction current 536A (1400 ℃), to prepare the p-SiC nanowires , nanowires with core - shell structure, the inner layer of single crystal p-SiC outer amorphous Si02. Nanowire distribution disorder, surface roughness, and between 50 ~ 200 nm in diameter and up to a few hundred microns in length along the lt; 111 gt; growth direction. . Carbon source, with the amount of carbon, the experimental parameters of the reaction of current and reaction time prepared SiC nanowire morphology carbothermal reduction and growth mechanism. The results show that, the crystal structure of the product prepared under different experimental parameters for the p-SiC, but the morphology of very different. Sheet, bamboo-like, pagoda-like beaded SiC nanostructures were prepared under different carbon content; reaction current (temperature) has a decisive impact on the SiC nanowires, the current lower reaction (temperature), the over-saturation is too small to form a stable nuclei, the low yield of the SiC nanowires; current (temperature) is too high, the degree of supersaturation is too conducive to generate the SiC nanoparticles unfavorable SiC nanowires generation; reaction time on the the SiC nanowires yield and diameter affect not increasing as prolonged reaction time, the length of the nanowires, the gradually smooth surface. As the metal catalyst is not introduced during the reaction, and the FE-SEM and TEM analysis showed that no droplets of the metal catalyst nano-wire tip, we prepared a nanowire based on gas - the growth of the solid growth mechanism. Study room temperature photoluminescence properties of SiC nanowires, field emission properties and photocatalytic properties. Excited by light of a wavelength of 275 mn, SiC nanowires at 300 nm has a strong UV emission peak; SiC nanowire field emission performance can be enhanced by annealing heat treatment, the field intensity in the opening before and after the 700 ° C annealed 3h were 9.5V/μm and 7.5 V / gm, the mechanism of the field emission quantum tunneling mechanism; Degradation of Methylene Blue solution efficiency up to 72.2% in after UV irradiation 6h, SiC nanowires.

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