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

2007; Elsevier BV; Volume: 254; Issue: 1 Linguagem: Inglês

10.1016/j.apsusc.2007.07.044

1873-5584

Mariano Escobar, M. Sergio Moreno, Roberto Candal, M. Claudia Marchi, Alvaro Caso, Pablo Polosecki, G.H. Rubiolo, Silvia Goyanes,

Nanotechnology research and applications

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 nanotubes were characterized by HR-TEM, SEM and DRX. TGA and DTA were also carried out to study degradation stages of synthesized CNTs. MWCNTs synthesized with low acetylene concentration are more regular and with a lower amount of amorphous carbon than those synthesized with a high concentration. During the synthesis of CNTs, amorphous carbon nanoparticles nucleate on the external wall of the nanotubes. At high acetylene concentration carbon nanoparticles grow, covering all CNTs’ surface, forming a compact coating. The combination of CNTs with this coating of amorphous carbon nanoparticles lead to a material with high decomposition temperature.