New nanocarbons : rod milling and annealing of graphite in the presence of yttrium

This work investigates the mechanisms of ordering and disordering graphite in the presence of 1% and 10% yttrium through mechanical activation and subsequent thermal annealing at 1350 °C for 6 h. Some work was done using other metals. Structural information was obtained by characterizing the milled and annealed samples by laser Raman spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) spectroscopy. In the initial stages (less than 72 h milling), yttrium assists in reducing the effects of rod milling on crystallite size but not in later equilibration between broken and reformed crystallites. Examination by TEM of all annealed samples with iron, cobalt, yttrium, or nickel revealed the formation of graphite, iron, cobalt, or nickel nanoparticles encapsulated with carbon strips but not for yttrium. No evidence of carbon nanotubes was found under the milling conditions for periods of 0-240 h and annealing temperatures up to 1350 °C for 6 h.