Electron microscopy and electron energy loss spectroscopy studies of carbon fiber formation at Fe catalysts

Nanofibers were produced by the chemical vapor deposition method in the presence of Fe-catalyst particles at temperatures of 700-850 K by disproportionation of CO. Electron diffraction and high resolution electron imaging as well as electron energy loss spectroscopy and x-ray analysis techniques were used to study the nanofiber formation in different places at the catalyst surface. The particles enclosed by the fibers were found to be Fe7C3 and Fe3C. Crystallographic relationships between deposit and particle were established. The structural properties of the deposit were found to be dependent on the position at the particle surface. Graphitic growth was favored at certain facets. At the particle tip graphene sheet formation competed with Fe2O3 oxide formation. We also report the occurrence of a low loss feature between 3 and 4 eV, concurrent with the dispersion of an interface plasmon at the graphite/Fe2O3 interface. (C) 2002 American Institute of Physics.