核壳结构SiC/SiO2纳米线的低温合成与表征

以酚醛树脂(PF)作为碳源, 纳米SiO₂为硅源, 在1300℃氩气气氛下通过碳热还原反应, 制备出具有核壳结构的SiC/SiO₂纳米线。采用X射线分析衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨率透射电子显微镜(HRTEM)、拉曼光谱(Raman)对产物的组成、形貌、微观结构等进行了表征。结果表明; SiC/SiO₂纳米线长可达数毫米, 单根SiC/SiO₂纳米线由直径30 nm的β-SiC晶体为内核和厚度约12 nm的无定形SiO₂壳层组成; 室温下SiC/SiO₂纳米线的PL发光峰与β-SiC单晶的发光特征峰相比有蓝移。最后, 讨论了核壳结构SiC/SiO₂纳米线的生成机制。

Synthesis and Characterization of Core-shell SiC/SiO2 Nanowires at Low Temperature

Core-shell SiC/SiO₂ nanowires were synthesized with formaldehyde resin as the carbon source and SiO₂ nano-powder as the silicon source at 1300℃ under argon atmosphere via the carbothermal reduction. The component, morphology and structure of the synthesized core-shell nanowires were systematically studied by X-ray diffraction, scanning electron microscope, transmission electronic microscope, high-resolution transmission electron microscope, and Raman spectroscope. The results show that the synthesized products are high-purity nanowires and it is found that the nanowires are quite uniform. The length of the nanowires can reach several millimeters, and the core-shell SiC/SiO₂ nanowires consist of a single crystalline β-SiC core with a diameter of about 30 nm and a uniform amorphous SiO₂ outer shell with a thickness of 12 nm. Compared to the single crystalline β-SiC, the emission spectrum from the photoluminescence of the as-synthesized core-shell SiC/SiO₂ nanowires has blueshift at room temperature. The formation mechanism of the core-shell SiC/SiO₂ nanowires is also discussed. The SiC core is grown in high temperature based on the vapor-solid mechanism. During cooling, the amorphous SiO₂ shell is formed by the reaction between SiO and CO gas.