采用水热法在高压反应釜内的高温、高压超临界水热环境下，以去离子水为反应介质，使活性高且难溶于水的一氧化硅粉末（SiO）通过硅原子的重结晶成核生长出本征硅纳米线。通过温度控制仪控制高压反应釜内温度和压力的变化，探索制备硅纳米线的最佳水热条件。通过多次实验探索，得知水热法制备硅纳米线的最佳条件是温度大于等于 450℃、压力在 9 ～ 10MPa。然后通过扫描电子显微镜（SEM）、能量色散 X 射线光谱仪（EDX）、高分辨透射电（HRTEM）观察 SiNWs 的形貌和结构，分析其组成成分。通过 SEM 可观察到硅纳米线表面光滑、最小直径达 50nm 及长度为 3 ～ 5μm，由EDX 图像可知 SiNWs 中只有硅和氧两种元素，而且 Si ∶ O 原子数比为 3.5 ∶ 1.0。在 HRTEM 下可知硅 纳米线是由芯部的晶体硅结构和外部无定形的二氧化硅包覆层组成，且包覆层小于 5nm。研究了本征 SiNWs 的拉曼光谱，发现拉曼主峰蓝移且在低频发生不对称宽化，分析认为是硅纳米线中存在的压应力和缺陷导致的。同时，在实验的基础上解释水热法制备 SiNWs 的机制，SiO 在水热环境下歧化反应生成硅和二氧化硅，然后 Si 和 SiO2 开始堆叠生成SixO，即大量的纳米团簇，在一定温度下硅原子重结晶，同时在 SixO 的引导下沿一维方向生长。
Intrinsic silicon nanowires were prepared using hydrothermal method, with high activity silicon oxide powder (SiO) as raw material and deionized water as reaction medium, made through recrystallization and nucleation growth of the silicon atom in high temperature and high pressure supercritical water thermal environment in high pressure reaction kettle. The best hydrothermal conditions to prepare silicon nanowires were explored. It showed that the best condition of hydrothermal preparation of silicon nanowires was temperature of more than 450 ℃ and pressure of 9 ~ 10 MPa by multiple experiments exploration. Through the scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDX) and high resolution transmission electron microscopy (HRTEM), the morphology and structure of SiNWs were observed and analyzed,and its components were analyzed. SEM showed that the surface of silicon nanowires was smooth,and its minimum diameter was 50 nm and its length was about 3 ~ 5μm. It could be seen that SiNWs was made up of only silicon and oxygen elements,and silicon and oxygen atom number ratio was 3.5 ∶ 1.0 by EDX image. Under the HRTEM, it showed that silicon nanowires was composed of crystalline silicon structure in the core and external amorphous silica cladding layer less than 5 nm. The Raman spectrum of intrinsic SiNWs showed that the Raman main peak occurred blue shift and asymmetric widening in low frequency due to the stress pressure and defect in SiNWs. The growth mechanism of preparation SiNWs by hydrothermal could be explained on the basis of experiment. SiO in water thermal environment reaction formed silicon and silicon dioxide by disproportionation, then Si and SiO2 began to stack formation a large number of nano clusters SixO,and silicon atom recrystallized in a certain temperature,at the same time, the nanowires grew under the guidance of the SixO SiNWs along the one dimensional direction.
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