▎ 摘　　要

The structure of multilayer carbon nanotubes is studied using digital image analysis to interpret high resolution TEM lattice images containing 002 and 100 fringes, in comparision with very thin vapour-grown carbon fibres with nanometer-sized diameter (nanofibres). The results show that the stacking of graphene shells in a multilayer nanotube glide with respect to one another, which is in contrast to th: stacking fidelity of three-dimensional graphite. The diffraction patterns derived from the fast Fourier transform of the lattice images yield angles of 0 degrees-17 degrees for the 100 lattice planes relative to the ideal 100 direction. The median inter-shell spacing d(002) between carbon nanotubes is also characterized, by using the 100 spacing as an internal standard, and d(002) range from 3.4 to 3.6 Angstrom. The inter-shell spacing d(002) decreases with increasing carbon nanotube diameter, which could be due to a size effect. The so-called vapour-grown carbon fibres (VGCFs), obtained by pyrolytic decomposition of hydrocarbon, are grown through spontaneous deposition of carbon layers on primarily formed nanotubes. In order to clarify the size effect for layer stacking, very thin VGCFs with diameter similar to 500 Angstrom, named nanofibers as well as submicron diameter VGCFs, are compared with carbon nanotubes, and are discussed in relation with the curvature of graphene layers. Some gently pulverized VGCFs with nm as well as mu m size diameters possess an exposed carbon nanotube at the core of the broken portion, suggesting a difference in the stacking structure of the graphene layers between the central core nanotube and the outer pyrolytic sections. (C) 1997 Elsevier Science Ltd.