Self-repairing in single-walled carbon nanotubes by heat treatment

TL;DR

This study uses molecular dynamics simulations to explore how single-walled carbon nanotubes can self-repair at high temperatures, revealing mechanisms that enhance their stability despite defects.

Contribution

It identifies two self-repair mechanisms in SWCNTs and demonstrates their role in maintaining structural integrity at elevated temperatures.

Findings

Self-repair mechanisms enable SWCNTs to recover from defects.

Critical collapse temperature is unaffected by vacancy defect density.

SWCNTs can seek stable configurations at high temperatures.

Abstract

Structure transformation by heat treatment in single-walled carbon nanotubes (SWCNT) is investigated using molecular dynamics simulation. The critical temperature for the collapse of pure SWCNT is as high as 4655 K due to strong covalent carbon-carbon bonding. Above 2000 K, the cross section of SWCNT changes from circle to ellipse. The self-repairing capability is then investigated and two efficient processes are observed for the SWCNT to repair themselves. (1) In the first mechanism, vacancy defects aggregate to form a bigger hole, and a bottleneck junction is constructed nearby. (2) In the second mechanism, a local curvature is generated around the isolate vacancy to smooth the SWCNT. Benefit from the powerful self-repairing capability, defective SWCNT can seek a stable configuration at high temperatures; thus the critical temperature for collapse is insensitive to the vacancy defect density.