Synthesis and characterization of SWNT-heavy alkali metal intercalation compounds, effect of host SWNTs materials

Singlewall carbon nanotubes (SWNTs) produced by electric-arc and laser ablation methods were characterized by X-ray diffraction before and after the reaction with alkali metals (M = K, Rb, and Cs). Reaction with annealed SWNTs gave MC8 composition at saturation. The alkali metal lattice showed short range order incommensurate with graphene cylinders of SArNTs. X-ray diffractogram simulations have enabled the study of the influence of SWNTs structure on that of intercalation compounds. Chemically-purified bundles, constituted of open SWNTs, can be intercalated inside and between the tubes forming disordered structures. Annealed or pristine bundles were intercalated only between the tubes leading to short or long range ordered structure depending on host crystallinity and alkali metal (K, Rb or Cs). The expansion of the 2D SWNTs lattice after intercalation is comparable to graphite intercalation compounds. Some 2D arrangements of SWNTs and K atoms are proposed and discussed to reproduce XRD results. C-13 NMR and ESR studies of annealed doped SWNTs emphasize the fact that the intercalation compounds of SWNTs are metallic. (C) 2003 Elsevier Science Ltd. All rights reserved.