Abstract:
Using in situ x-ray diffraction and Raman scattering techniques, we
have investigated the behaviour of single-walled carbon nanotubes bundles under
non-hydrostatic pressures. It is seen that the diffraction line corresponding to the
two-dimensional triangular lattice in the bundles is not reversible for pressures
beyond 5 GPa, in sharp contrast to earlier results under hydrostatic pressure
conditions. Most interestingly, radial breathing and tangential Raman modes of
the pressure-cycled samples from 21 and 30 GPa match very well with those of
the starting sample. Raman and x-ray results put together clearly suggest that
the ordering of tubes in the bundles is only marginally regained with a very short
coherence length on decompression.
