Effect of process variables on carbon nanotubes synthesis

D. ZILLI; S. N. GOYANES; G. R. RUBIOLO; A. L. CUKIERMAN

RIO NEGRO, ARGENTINA

Congreso; NSF-CNEA PAN AMERICAN ADVANCED SCIENCE INSTITUTE ON PHYSICS AT THE NANOMETER SCALE; 2003

Instituto Balseiro , National Science Foundation

Large arrays of well-aligned carbon nanotubes (CNTs) were obtained by chemical vapordeposition (CVD) of iron (II)phtalocyanine, an organic-metal complex which contains boththe metal species and the carbon source required for CNTs nucleation and growth. Thoughthis process has been earlier applied, the incidence of the operating conditions on thecharacteristics and/or properties of the developed CNTs have not been systematicallyexamined at least in the open literature. The synthesis of CNTs was carried out under Ar/H2in a flow reactor heated by a dual furnace with independent temperature controllers. Mainconditions explored were: gas composition (Ar/H2: 1:1, 1:2 v/v), total gas flow rate (10-100cm3/min), pyrolysis temperature (750-1050 °C), and total reaction time (25-40 min). TheCNTs obtained under the different operating conditions were examined by scanning andtransmission electron microscopy (SEM and TEM). CNTs features, i.e. length and verticalalignment, were found markedly dependent on the conditions used. In particular, anexponential increase of CNTs length with the pyrolysis temperature was determined underotherwise constant conditions. High gas flow rates with Ar/H2: 1.2 v/v led to a pooralignment of the CNTs. Growth of CNTs onto different metallic substrates was alsoinvestigated.