SYNTHESIS AND STRUCTURE OF PRISTINE AND ALKALI-METAL-INTERCALATED SINGLE-WALLED CARBON NANOTUBES

Single-walled carbon nanotubes (SWNTs) were synthesized by ablating gr aphite targets with either the primary (1064 nm) or the second-harmoni c (532 nm) beam of a pulsed Nd:YAG laser at high temperature. The stru cture and the morphology of the raw materials were studied by high-res olution transmission microscopy (HRTEM), X-ray diffraction, and micro- Raman techniques. The diameter distribution of the SWNTs was found to vary with the laser frequency used for ablation. The raw materials wer e reacted with alkali metal (K, Cs) by vapor transport method. The sat uration composition was found to be MC(8)s (M = K or Cs). No crystalli ne structure was observed in the reacted materials by X-ray diffractio n. In situ metal deposition, TEM, and electron energy loss spectroscop y (EELS) measurements were performed on individual SWNT bundles at 300 K. The results showed that alkali metals can be reversibly intercalat ed into the SWNT bundles. Although intercalation induced structural di sorder, individual nanotubes and to a large extent the bundles maintai ned their structural integrity after intercalation and de-intercalatio n.