Abstract
Structural properties of carbon peapods, C-60, trapped into single-walled carbon nanotubes (SWNT), have been studied under high-pressure/high-temperature conditions (HPHT) by in situ x-ray diffraction. The C-60 chain structure together with the influence of the filling on the SWNT change under HPHT treatment is investigated. Synthesis of a one-dimensional polymer chain of C-60 inside the single-walled carbon nanotubes is evidenced. At 4 GPa, increasing the temperature up to 1023 degrees C leads to a progressive C-60 polymerization that is associated to a shortening of C-60-C-60 distance down to 8.7 A. Back to ambient conditions, the C-60 chain remains polymerized, emphasizing the high stability of this material. In addition, our data strongly suggest a symmetry change of the two-dimensional bunde lattice under pressure.