Control of nano-carbon synthesized in liquid phase under high magnetic field

碳纳米管的合成通常采用多种化学气相沉积（CVD）方法、电弧放电和激光烧蚀技术。这些合成方法需要较高的合成温度，至少500℃。低温合成对于纳米管和纳米线在实际器件中的应用具有重要意义。自从我们报道了利用电化学技术在室温下合成纳米碳以来，高达12特斯拉的高磁场被应用于电化学技术合成碳纳米管。利用扫描电镜（SEM）、透射电镜（TEM）和能谱仪（EDS）对沉积物进行了表征。透射电镜观察到长碳纳米线在磁场作用下增加。此外，高达12特斯拉的高磁场被应用于碳纳米管的热CVD合成。透射电镜观察到洋葱状纳米碳的增加和磁场作用的增加。除了这些合成方法外，我们还发现了另一种碳纳米管和碳纳米线的室温合成方法。用金属催化剂和金属Na在有机溶液的液相中进行超音速辐照，实现了新的室温合成。沉积过程中的温度升高可以忽略不计，因为最多只有几度。这种低温合成方法对于开发碳基新材料具有很大的优势。此外，在本研究中使用的仪器简单，不昂贵。因此，该技术将为开发其他纳米级新材料提供可能。

Carbon nanotubes have been commonly synthesized using a wide variety of chemical vapor deposition (CVD) methods, arc discharge and laser ablation techniques. These synthesis methods require a high synthesis temperature, at least 500℃. A low-temperature synthesis is important for an application of nanotubes and nanowires to practical devices. Since we have reported the room temperature nano-carbon synthesis by electrochemical techniques, high magnetic fields up to 12 Tesla are applied to electrochemical techniques for carbon nanotube synthesis. The deposits were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). An increase in the long carbon nanowires due to magnetic field was observed by TEM. In addition, high magnetic fields up to 12 Tesla are applied to thermal CVD for carbon nanotube synthesis. An increase in the onion-like nano-carbons and due to magnetic field was observed by TEM. Beside these synthesis methods, we have discovered another room temperature synthesis method of carbon nanotubes and carbon nanowires. The new room temperature synthesis has been achieved by a supersonic irradiation into a liquid phase of organic solution with a metal catalyst and metal Na. The temperature increase during the deposition is negligible, because of by a few degrees at most. This low temperature synthesis method has a great advantage to develop carbon-based new materials. In addition, the apparatus used in the present study is simple and is not expensive. Therefore, this technique will make it possible to develop other nanosized new materials.