High pressure behavior of single-walled carbon nanotubes and polymerized fullerenes

In situ synchrotron X-ray diffraction measurements of single-walled carbon nanotube (SWNT) bundles and two types of pressure-polymerized fullerenes under high pressure were carried out. It was found that their unit cells shrink anisotropically by compression. In both cases of rhombohedral (rh-) and tetragonal (t-) C-60 polymers, the distances between polymerized planes decrease largely with increasing pressure, while the center-to-center distances Of C-60 clusters in the same polymerized plane decrease less with pressure. In the case of SWNT bundles, the magnitudes of the shifts of the diffraction peak positions by compression greatly vary with hkl indices. It was also found that the decrease of the d-value of 100 line by compression is too large not to allow deformation of the individual tubes. Bulk moduli of rh-C-60, t-C-60 polymers and SWNT bundles were determined using the observed XRD patterns. (C) 2003 Elsevier Ltd. All rights reserved.