Deformation of catalytically grown carbon nanotubes induced by annealing under high pressure

A study of the structural transformation of catalytically grown carbon nanotubes induced by annealing under high pressure is presented in this paper, in which the atomic details of the microstructural transformations have been monitored mainly with electron microscopy. The microstructural change from the multiwalled carbon nanotubes into a quasi-spherical onion becomes obvious just at 770 °C under 5.5 GPa. The nanotubes deform and almost transform into nanographite ribbons directly when the annealing temperature is above 950 °C under 5.5 GPa. It is suggested that the pressure and temperature play an important role in the structural transformations of multiwalled carbon nanotubes described here.