Abstract Submitted to the NANOTUBE'02 Workshop:

The formation of multiwall carbon nanotubes from thermal and plasma CVD processes via a catalytic process is examined. In particular details of HREM studies on the MWNT catalyst interface are presented to the vapour-liquid-solid (VLS) formation model. From this some implications are drawn on the influence of catalyst particle size on tube diameter and structure. It is shown that in plasma growth conditions surface diffusion of the carbon on the catalyst particle is more possible. This in-turn leads to more rapid and less control on the MWNT structure. However, in terms of oriented growth, and control of macroscopic features, plasma is preferred. The reasons as to why the VLS model for MWNT formation can result in very narrow inner core tubes is discussed. In particular the stability of a sub 4 A inner tube where the requirement to have a hemispherical end cap is removed is considered. Data which suggests that ultra-narrow tubes are formed in MWNTs from CVD is presented.