ELECTRON-MICROSCOPY STUDY OF COILED CARBON TUBULES

Carbon fibres prepared by the catalytic decomposition of acetylene over finely dispersed cobalt, supported on amorphous silica, are often helix shaped. The structure of such carbon fibres was studied by means of various electron diffraction techniques and by electron microscopy. It was shown that the tubules are hollow and consist of concentric cylindrical graphene sheets. The diffraction patterns are analysed in detail and compared with theoretically predicted patterns. Good semi-quantitative agreement is found. It is shown that the helices are polygonized; their atomic structure is consistent with models predicted on the basis of molecular dynamics simulations.