The structural and magnetic properties of nano-sized particles of transition
metals (Co and Ni) implanted into amorphous SiO2 are
investigated. The SiO2 substrates used were as grown on a silicon
(100) wafer under wet O2 atmosphere. The metals were implanted as
singly charged atoms energized to 30 or 160 keV. Transmission Electron
microscopy (TEM) observations and X-ray absorption spectroscopy (XAS) show
that M+ implantation results in the formation of metallic
nanoparticles at the vicinity of the surface whereas oxide particles (< 1
nm) are formed in a deeper region. After thermal treatment under hydrogen,
TEM evidences the disappearance of the oxide region and an increase in the
size of the metallic particle. XAS shows that cobalt and nickel are entirely
in the metallic form and saturation magnetization becomes close to the
theoretical value.