中文摘要：

室温下利用高分辨透射电子显微镜原位观察了两端固定和一端固定、另一端自由的双壁碳纳米管在电子束辐照下的结构不稳定性.实验发现,在相同辐照条件下,两端固定的双壁碳纳米管首先径向持续均匀收缩,然后局部颈缩,最后在颈缩处断裂;一端固定、另一端自由的双壁碳纳米管轴向长度持续快速缩小,而径向收缩相对缓慢.我们利用最近提出的表面纳米曲率效应和能量束诱导非热激活效应基础上新发展的碳原子＂融蒸＂和＂扩散＂机制,对上述电子束辐照下双壁碳纳米管结构不稳定现象进行了全新、合理的解释.

英文摘要：

The structural instabilities of double-walled carbon nanotubes in two typical environments were investigated in situ by transmission electron microscopy at room temperature. The double-walled carbon nanotube with two fixed ends shrank uniformly in the radial direction, bent locally and finally broke. The double-walled carbon nanotube with one free capped end and the other fixed to a rope of nanotubes shrank quickly and continually in the axial direction and slowly in the radial direction. All experimental phenomena could be well accounted for by the vaporization and diffusion of carbon atoms driven by the surface nanocurvature effect and electron beam-induced athermal activation, which have been underestimated or neglected in existing theoretical descriptions and simulations.