Rubidium localization in single-walled carbon nanotube bundles: Structural study
Résumé
X-ray and neutron-diffraction investigations of rubidium-intercalated single-walled carbon nanotubes are reported. Ab initio calculations conducted in combination with our experiments show that for a single Rb ion the most energetically favorable intercalation site is the interstitial channel between three tubes in a bundle. At higher doping levels, as the Rb content increases, this site becomes however unfavored with respect to the interior of the tubes or the external surface of the bundle. Model simulations of the diffraction patterns, capable of well reproducing both the x-ray and neutron-diffraction patterns, indicate that only the latter insertion sites are compatible with the experimental data. Finally we show that the bundle surface site is the most probable one in the case of saturation at an estimated stoichiometry close to RbC8.