Imaging lattice defects and distortions in alkali-metal iodides encapsulated within double-walled carbon nanotubes

The alkali-metal iodide double-walled carbon nanotube composites MI@DWNTs (M = K, Cs) have been prepared using a melt-phase filling procedure. The imaging and subsequent structural analysis of the encapsulated metal iodide crystals was performed with a combination of phase restored high-resolution transmission electron microscopy technique, structural modeling, and image simulation. The atomically resolved structures of the MI crystals were seen to contain several lattice defects including interstitials and vacancies as well as distortions of the crystal planes including shearing and rotation.