New Data on the Formation of SWNTs by the Electrical Arc Method
Résumé
The formation of single‐wall carbon nanotubes (SWNTs) and other carbon nanophases by the electric arc method was investigated by transmission electron microscopy for various conditions while studying the plasma characteristics (temperature profiles, C2 concentration) by in‐situ emission spectroscopy. Special attention was brought to the anode type, which has not been a thoroughly studied parameter so far. Related parameters were the dispersion of the catalyst (homogeneous or heterogeneous) and the doping with non catalyst phases. Conditions have been found which are able to produce preferentially either SWNTs, or double‐wall nanotubes (DWNTs), or single wall nanocapsules (SWNCs). Focussing on the formation of SWNTs, we also determined arc conditions where web production is increased by up to ∼230% compared to standard conditions. Impurities are only catalyst remnants and amorphous ‐ or nearly ‐ carbon, suggesting that acid‐based purification procedures could be simplified and less severe, with both higher efficiency and lower harmfulness towards SWNT structure. Investigation of the plasma provided interesting results which emphasise the role of the primary structure of the active carbon moieties generated by the anode vaporisation. The unexpected minimisation of the role of C2 in the SWNT growth mechanism is one of the results.
Origine : Fichiers éditeurs autorisés sur une archive ouverte