Fe, Co, and Ni magnetic nanoparticles have been characterized
using energy-selected imaging in a high-resolution transmission
electron microscope. The samples comprised Fe/FeOx
and Co/CoOx nanoparticles synthesized by inert gas
evaporation and a Ni/C nano-composite prepared by a sonochemical method.
All of the particles examined were found to be between 5 and
30 nm in size, with the Fe and Co crystals coated in 5–10
nm of metal oxide layer and the Ni metallic crystallites embedded
in an amorphous carbon spherical matrix.