碳化硅纳米线合成及显微结构分析

Synthesis of SiC Nanowires in Fluidized Bed and Its Microstructure

利用悬浮床,以Si粉为原料,在0.2L/min的高纯氮气中,维持反应温度1～600℃,悬浮反应30min,在预先放置的收集器上得到了SiC纳米线,XRD结果表明所得SiC纳米线为部分结晶状态,结晶态晶型为六方6H型。SEM形貌观察结果表明,所得SiC为纳米线。进一步SEM观察发现,大量纳米线的端部有球状液滴存在,VLS机制为该纳米线的主要形成机制,通过EDX能谱对比分析,纳米线端部球状液滴中相对纳米线本身含有较多的氧元素,因此,氧元素对于通过VLS机制形成SiC纳米线起到了促进作用。TEM观察显示,纳米线中存在大量的堆垛层错缺陷。

Element Si was employed to synthesize SiC nanowire at a high purity nitrogen flow of 0.2 L/min in a fluidized bed. The temperature of the reaction was maintained at 1600℃ for 30 min. SiC nanowire could be obtained at the bottom of receiver. XRD analysis results revealed that the crystal type of as-received products were 6H type. SEM observation showed that the diameter of the nanowire was about 20-40 nm and the aspect ratio was conducted to be over than 1 × 10^3. SEM image also revealed the formation mechanism of the nanowire, from which VLS mechanism could be proposed. Comparing the EDX spectra, droplets at the top of nanowires had more O element than nanowires themselves. Therefore O element promoted the formation of SiC nanowires by VLS mechanism. TEM observation showed that there was much stacking fault in nanowires.