Published online by Cambridge University Press: 15 February 2011
Details of the carbon-coated nanoparticle growth mechanism are revealed by a comparison of product morphology and reactor parameters. Carbon-coated metal or metal carbide clusters nucleate in the gas phase, grow to characteristic sizes, and deposit on surfaces within the reactor. The surface temperature determines the crystallinity of the nanoparticles and the surrounding carbon. Tungsten carbide nanoparticles show that the carbon coating arises due to phase segregation when the nanoparticle has a lower melting point than that of graphite.