SEM and HREM study of the internal structure of nanotube rich carbon arc cathodic deposits Original Research Article

The structural components and the internal organization of carbon cathodic deposits fabricated using an arc with the conditions adjusted for the effective production of nanotubes have been characterized by transmission electron microscopy (TEM), high resolution electron microscopy (HREM) and scanning electron microscopy (SEM). Typically, such deposits are columnar structures oriented along the growth direction. Three main components were observed: multiwalled nanotubes, multilayer polyhedral particles and curved graphitic formations. The measured distributions and relative quantities of the components depended on the deposition regimes. Column interiors were composed of a mixture of all these components, while the outer covering of the columns was formed predominantly of nanotubes. Multiwalled nanotubes formed a mesh-like arrangement around these columns and their growth surfaces, with smaller amounts of nanotubes present inside the columns. Nanotubes in various fragments of the deposits were mainly oriented at high angles to the deposit axes. In the column coverings, groups of tubes oriented at angles >45° to the axes were present with no sets of nanotubes or bundles aligned along the deposit axes seen. Finally, a mechanism of deposit formation is proposed in connection with the recorded data.