| The morphology and structure of nanoparticles produced in modified Kratschmer-Huffman carbon arc reactors are discussed and possible growth models for the particles are suggested. After a description of the experimental techniques used to produce nanoparticles in carbon arc reactors, characterizations of nanoparticles using x-ray powder diffraction, energy dispersive x-ray analysis, electron energy-loss spectroscopy, and conventional, high resolution, and energy-filtered transmission electron microscopies are presented. Materials chemistry, synthesis conditions, and deposition location within the reactor are found to affect the morphology and crystallinty of the nanoparticle-containing powder. Competing growth models proposed in the literature are reviewed and evaluated in the context of a broad base of observations. The cogent pieces of these mechanisms are retained and combined with new observations to form a new growth model based on gas phase nucleation and phase segregation driven by melting point differences. |
