Intercalation into carbon nanotubes without breaking the tubular structure

We report the first observation of intercalation into carbon nanotubes without breaking the tubular structure. Both K-intercalated and FeCl₃-intercalated tubes were produced by a gas-phase reaction of oriented multiwall "buckybundle" material with potassium metal and iron (III) chloride, respectively. The resulting material preserves its oriented structure. It has been studied by X-ray diffraction, SEM, weight uptake and magnetoresistance measurement techniques. Interlayer spacing in the intercalated tubes is very close to that in corresponding graphite intercalation compounds. It has been shown that intercalated buckybundles exhibit some noteworthy galvanomagnetic properties including the random conductance fluctuations. The intercalation process is accompanied by swelling of the tubes. The swollen sections alternate non-intercalated "necks" forming an impressive "bead-line" pattern.