Molecular dynamics simulations of healing of a hole in a carbon nanotube under electron irradiation

Molecular dynamics simulations are performed to study healing of a hole in a carbon nanotube under electron irradiation in HRTEM at room temperature. The calculations are carried out using the CompuTEM algorithm as implemented in the MD-kMC code. Hole healing occurs in all the simulation runs. An amorphous patch is formed in the absence of external carbon adatoms only via saturation of dangling bonds. The patch consists of non-hexagonal rings, mostly of 5-, 6- and 7-membered rings, and its formation is accompanied by CNT buckling and narrowing. The amorphous patch growth is observed under further irradiation. Two-coordinated atoms play a leading role in this process.本研究开展分子动力学模拟（Molecular dynamics simulations），以探究室温环境下，高分辨透射电子显微镜（High-Resolution Transmission Electron Microscopy, HRTEM）中电子辐照条件下碳纳米管（carbon nanotube, CNT）孔洞的愈合过程。计算采用MD-kMC代码集成的CompuTEM算法完成。所有模拟运行均观测到孔洞愈合现象。在无外部碳吸附原子的条件下，仅通过悬键饱和即可形成非晶补丁结构；该补丁由非六边形环构成，以五元、六元及七元环为主，其形成过程伴随碳纳米管的屈曲与管径缩窄。进一步辐照下可观测到该非晶补丁的生长过程，其中二配位原子在该演化过程中发挥主导作用。