Uniaxial tension/compression effects on the electrical properties of carbon nanotube bundles: A first-principles study

In this work, we studied the effect of uniaxial tension/compression on the electrical properties of carbon nanotube bundles within the framework of density functional theory. The bundles consist of mono-chirality single-walled carbon nanotubes. The band gap response of the bundles shows different electrical characteristics including band gap opening, closing and non-linear behaviors, where the affected band gap is significantly dependent on the chirality of the constituent tubes. Calculations reveal that the bundles express a systematic down-shift in the Fermi energy as a consequence of the applied tension, and a systematic up-shift in the Fermi energy in response to the applied compression. Furthermore, the simulation results show a nonlinear behavior in Fermi energy for bundles under test. This nonlinear behavior in Fermi energy may be caused by asymmetrical electronic effects in both conduction and valance bands. For all bundles, the weak wall-to-wall interactions have considerable effects on electrical properties compared to single-walled carbon nanotubes. We hope this study does not only provide helpful enlightenment on the effects of uniaxial strain on electrical properties of bundles, but also opens exciting opportunities for potential applications of piezoresistive nano-devices.