The formation of low-dimensional ionic crystallites in carbon nanotubes

Atomistic computer simulation models are used to interpret the results of recent high resolution transmission electron microscopy (HRTEM) experiments which have studied the filling of carbon nanotubes by liquid KI. In the HRTEM experiments, the liquid KI fills narrow width nanotubes to form low-dimensional crystallites which display specific distortions in comparison with the idealized bulk fragments. The atomistic origin of these distortions are discussed. Molecular dynamics simulations are then used to directly model the filling of these tubes and an understanding of the filling mechanisms is developed. The dependence of the filling structure on the pore radius and morphology of the carbon nanotube is discussed. Novel crystalline structures, often incorporating specific twisting, is observed for the smaller diameter nanotubes. The physical origins of the observed filling mechanisms are discussed.