稀土氧化物催化碳纳米管的形成(英文)

Formation of carbon nanotubes catalyzed by rare earth oxides

利用爆炸辅助的化学气相沉积方法,以一系列稀土元素作为催化剂合成了多壁碳纳米管(MWCNTs)。通过能量色散X射线谱、选区X-射线电子衍射谱和粉末X-射线衍射数据表明,催化剂是以氧化物形式存在MWCNTs外,这不同于传统的以金属或碳化物存在。结合中间体结构,结果显示,MWCNTs的形成遵循颗粒-线-管逐级进化的机制,稀土氧化物可能在促进碳纳米颗粒的各向异性的自组装过程中起主要作用,空腔是通过颗粒之间结构的重组和晶化进化形成。

Multi-wall carbon nanotubes （MWCNTs） were synthesized by detonation-assisted chemical vapor deposition using a series of rare earth （RE） oxides as catalysts. Energy dispersive X-ray spectroscopy, selected area electron diffraction and powder X- ray diffraction show that the catalysts, usually located outside the MWCNTs, have not been reduced, in sharp contrast to conven- tional catalysts in the form of metals or carbides. With the help of intermediate objects found in TEM images, it is proposed that the formation of MWCNTs follows a particle-wire-tube step-wise evolution mechanism. The RE oxides may play a major role in promo- ring the self-assembly of anisotropic carbon nanoparticles into a 1-D structure, and the cavities in the tubes evolve through structure self-reorganization and crystallization of the particles.