par Visart de Bocarmé, Thierry 
;Moors, Matthieu ;Kruse, Norbert
Référence European Conference on Surface Science (ECOSS) (28: 2011-08-28 -> 2011-09-05: Wroclaw, Pologne)
Publication Non publié, 2011-08-30
;Moors, Matthieu ;Kruse, Norbert Référence European Conference on Surface Science (ECOSS) (28: 2011-08-28 -> 2011-09-05: Wroclaw, Pologne)
Publication Non publié, 2011-08-30
Communication à un colloque
| Résumé : | Carbon nanotubes exhibit physical and chemical properties of the highest interest for future applications in various fields. The most widely used synthesis method is the Chemical Vapor Deposition (CVD) process which is based on the decomposition of a carbon containing gas (C2H2, CH4, C2H5OH…) on a metallic catalyst (Ni, Co, Fe…) at a temperature between 400 and 900°C, followed by the growth of carbon filaments on the metal particles. The present work aims at studying nucleation-related phenomena using a combination of Field Ion and Electron Emission Microscopy (FIM/FEM) and atom-probe techniques. These methods provide structural and chemical information with nanoscale lateral resolution during the ongoing interaction between reactive gases and sharp metallic tips. The extremity of these tips is imaged in real time by FIM and/or FEM and their local chemical composition can be monitored by atom probe using field pulses of well-chosen frequencies. By their size and morphology the samples can be considered as an excellent model of a single catalyst grain. Emphasis is put on the mechanisms governing the very early stages of the CVD process. In particular, carbon-induced morphological changes of Ni tips are visible by exposing them to C2H2 and C2H5OH at 350, 450 and 600 °C. The carbon-induced formation of steps has been inspected along with association reactions between individual carbon atoms. |
