Y. Yosida et al., SYNTHESIS, IDENTIFICATION, AND GROWTH-MECHANISM OF FE, NI, AND CO CRYSTALS ENCAPSULATED IN MULTIWALLED CARBON NANOCAGES, Journal of applied physics, 76(8), 1994, pp. 4533-4539
Nanometer size crystalline particles of alpha-Fe, gamma-Fe, Ni, beta-C
o, and Co3C encapsulated in multiwalled carbon cages are synthesized b
y a standard dc arc evaporation of composite anodes containing 10-15 w
t.% each of the metals or their compounds. The typical particle size i
s approximately 10 nm. Elemental analysis is made by x-ray energy disp
ersive spectroscopy. The spectra show only the peaks associated with t
he respective metal and carbon. The stoichiometry and phase of the cry
stals are assigned from the characteristic lattice spacings obtained b
y high-resolution transmission electron microscopy and x-ray diffracto
metry. Particle size distribution is obtained from a statistical surve
y of electron micrographs. A statistical growth model is adequate for
explaining the crystalline particle size distribution of the encapsula
ted crystals consisting of alpha-Fe and gamma-Fe smaller than 15 nm. S
ignificant deviation from the model is found for the encapsulated crys
tals consisting of alpha-Fe and gamma-Fe larger than 15 nm, those of N
i larger than 4 nm, and those consisting of beta-Co and Co3C larger th
an 6 nm. The deviation is discussed in terms of encapsulation effect o
n the particle growth mechanism.