Low-temperature annealing of radiation-induced defects in carbon nanotube bundles

The annealing of radiation-induced defects in carbon nanotube bundles below room temperature has been investigated experimentally. Significant feature of this study is that electron irradiation (with an energy 1MeV and fluence up to 1016el/cm2) was carried out at liquid helium temperature. A detailed analysis of the resistance change over a wide temperature range (7–300K) enables us to prove partial annealing of irradiation-induced defects at moderate temperatures. It is shown that such an annealing follows a first-order reaction in whole investigated temperature range. While at temperatures below 40K, annealing is nonactivation, tunneling process; at higher temperatures (100−300K) it becomes activated, with activation energy of ~0.05eV. The value of discovered activation energy is close to the migration energy of interstitial carbon atom in graphite. Probably, observed annealing of radiation-induced defects in carbon nanotube bundles is also caused by the migration of interstitial carbon atoms between single nanotubes below room temperature. [Display omitted] •Partial annealing of radiation-induced defects at moderate temperatures is proved.•Defects annealing at temperatures below 300K follows a first-order reaction.•It is found that annealing below 40K is nonactivation, tunneling process.•The activation energy of annealing at temperatures 100–300K is ~0.05eV.