Synthesis of Carbon nanotubes by CVD: Effect of acetylene pressure on nanotubes characteristics

ESCOBAR M.; MORENO S.; CANDAL R.J.; MARCHI C.; CASO A.; POLESECKI P.; RUBIOLO G.; GOYANES S.

Bariloche, RN, Argentina

Congreso; 13th International conference on solid films and surfaces; 2006

IB, CNEA,

Nota: este trabajo fue aceptado para su publicación en Applied Surface Science, luego de ser evaluado según los estándares exigidos por esa revista. Actualmente esta en prensa (pero no "on line") The effect of acetylene partial pressure on the structural and morphological properties of multi-walled carbon nanotubes (MWCNTs) synthesized by CVD on iron nanoparticles dispersed in a SiO2 matrix as catalyst was investigated.  The general growing conditions were: 110 cm3/min flow rate, 690 °C synthesis temperature, 180 torr over pressure and two gas compositions: 2.5% and 10% C2H2/N2 . The catalyst and the obtained nanotubes were characterized by HR-TEM, SEM and DRX. Also TGA and DTA analysis was used to study the degradation stages of the synthesized CNTs. At low acetylene concentration the MWCNTs are more regular, with a lower amount of amorphous carbon. During the synthesis of CNTs amorphous carbon nanoparticles nucleate on the external wall of the nanotubes. At high acetylene concentration the carbon nanoparticles growth, covering all the surface of the CNTs, in the form of a compact coating. The combination of CNTs with this coating of amorphous carbon particles lead to a material with high decomposition temperature.