SEM and HREM study of the internal structure of nanotube rich carbon are cathodic deposits

The structural components and the internal organization of carbon cathodic deposits fabricated using an are with the conditions adjusted for the effec tive production of nanotubes have been characterized by transmission electr on microscopy (TEM), high resolution electron microscopy (HREM) and scannin g electron microscopy (SEM). Typically, such deposits are columnar structur es oriented along the growth direction. Three main components were observed : multiwalled nanotubes, multilayer polyhedral particles and curved graphit ic formations. The measured distributions and relative quantities of the co mponents depended on the deposition regimes. Column interiors were composed of a mixture of all these components, while the outer covering of the colu mns was formed predominantly of nanotubes. Multiwalled nanotubes formed a m esh-like arrangement around these columns and their growth surfaces, with s maller amounts of nanotubes present inside the columns. Nanotubes in variou s fragments of the deposits were mainly oriented at high angles to the depo sit axes. In the column coverings, groups of tubes oriented at angles >45 d egrees to the axes were present with no sets of nanotubes or bundles aligne d along the deposit axes seen. Finally, a mechanism of deposit formation is proposed in connection with the recorded data. (C) 1999 Published by Elsev ier Science Ltd. All rights reserved.