Microscope studies of the morphology and structure of carbon nanotubes

Abstract

We have studied the morphologies and structures of carbon nanotubes (bucky-tubes) and carbon nanoparticles (buckyonions) using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning tunnelling microscopy (STM). By SEM the carbon nanotubes are observed with features similar to those of some fibrous whiskers grown from pyrolytic graphite. This growth feature is supported by transmission electron microscopy (TEM) observations. The TEM results show also that the graphitic sheets can be bent into curved shapes to cap the nanotubes or form the onions. In the curved graphitic sheets elastic strains induced by layer mismatches and dislocations are revealed. The STM observations on the nanotubes show a bundle-like morphology of the carbon nanotubes, and by atomic resolution images the zigzag and armchair atomic configurations may be identified. The results also show structural distortions which may be produced by folding the graphite sheets to create the nanotubes and are responsible for the lattice mismatch.