Defect formation and hysteretic inter-tube displacement in multi-wall carbon nanotubes

Using first-principles calculations on multi-wall carbon nanotubes (MWCNTs) we probe defect-related processes that bear on key properties. We find that self-interstitial (SI) ingression leads to bridges between the inner-most walls, minimizing carrier scattering in the outer-shells, but also possibly stabilizing radiation damage through vacancy-SI separation. The SI bridges amplify the corrugation, energy dissipation, and hysteresis under inter-wall displacement. They can thus be detrimental to MWCNT-based oscillators or actuators, or be exploited as nano-locks and heat nano-pumps.

The energy variation during inter-tube displacement of double-wall carbon nanotubes reveals that interstitial-related inter-shell bridges have a much more pronounced effect than vacancies and Stone–Wales defects. These bridges can be detrimental to various CNT-based nano-electromechanical systems as they introduce hysteresis and energy-dissipation.Figure optionsDownload as PowerPoint slideResearch highlights
► Ab initio determination of point defect stability in multiwall carbon nanotubes (MWCNTs).
► Defect ingression to inner-most shells of MWCNTs is energetically favorable.
► MWCNT interstitial–vacancy pairs can split due to differing ingression barriers.
► Interstitials form inter-shell bridges in MWCNTs.
► Inter-tube bridges dominate response to MWCNT inter-shell displacement.
► Defects create hysteresis, energy dissipation in MWCNT electromechanical systems.