Sequential catalytic growth of carbon nanotubes

The role of iron carbide in multiwalled carbon nanotube growth

“…In case of iron, irrespective of the well-known iron/carbon phase diagram for the macroscopic bulk material [11], the amount of carbon that can generally be incorporated into the high-temperature quasi-liquid nanoparticle is not well known. About 50 at.% carbon were measured in melted iron particles by Krivoruchko and Zaikovskii [12], and recently Jourdain et al [13] estimated from their computer image analysis of transmission electron microscope (TEM) images a carbon atomic ratio of even x C ∼ 0.68 in Ni/Fe metal particles.…”

“…However, the role metal carbides play in the synthesis of the various forms of carbon nanotubes and nanoparticles is a matter of debate. While, e.g., the catalytic activity of pure Fe 3 C in the decomposition and pyrolysis of acetylene has been proved negligible [22], its function as an intermediate in the transformation of amorphous carbon into graphite is still controversial [13,23,24]. Recently, evidence of the iron carbide phase (cementite) participating in the graphitization of amorphous carbon has been presented by Pérez-Cabero et al [25] using X-ray diffraction investigations, and by Sinclair et al [26] in an electron microscopy and diffraction analysis.…”

Controlling the Morphology of Multiwalled Carbon Nanotubes by Sequential Catalytic Growth Induced by Phosphorus

“…We formerly proposed a mechanism of sequential catalytic growth (SCG) for these nanomatch structures, based on a repeated sequence of induction± growth±interruption [27] ( Fig. 3).…”

“…Using an axial symmetry model to describe a unit, we calculated the carbon mass per unit, m C i , as a function of the mass of the catalyst particle, m P i . By this method we can demonstrate the existence of two different growth regimes: [27] d A linear regime for the smallest particles where the carbon mass of a unit is simply proportional to the mass of the catalyst particle that generates it.…”

Synthesis of Carbon Nanocapsules and Nanotubes Using Fe-Doped Fullerene Nanowhiskers

“…Carbon precipitates continuously on the same region of the particle, along one direction, leading to growth of 4 Journal of Nanotechnology the CNT [10]. According to Jourdain et al, a particle is encapsulated in a CNT owing to the strong interfacial tension between the inner wall of the CNT and the surface of the melting particle [31]. It is suggested that the interfacial tension of the rod-shaped particles encapsulated by CNTs is higher than that of the spherical particles in the CNCs.…”