CARBON NANO-TUBES - THEIR FORMATION PROCESS AND OBSERVATION BY ELECTRON-MICROSCOPY

Carbon nano-tubes have been investigated thoroughly by transmission el ectron microscopy. Non-helical tubes are not exceptional and mixing wi th helical tubes with various helicities is often observed within the same tubule. The helical nature of the tubes is thought to be actually required by lattice continuity during the formation of successive sea mless concentric tubes. Besides, introducing dislocations is also a po ssible accommodation mechanism for the strains produced between the su ccessive tube surfaces. Reciprocal space constructions have been accom plished for explaining the diffraction effects for non-helical tubes a s well as for helical ones. Well-resolved high-resolution images are o btained in particular for the non-helical tubes and the image features could be confirmed by computer simulations. A possible growth process for the successive concentric tubes is proposed.