Fe-Co-Ni particles with an average size of 45 and 135 nm are characterized
in terms of magnetic phase transformation and magnetic properties at room t
emperature. The bcc structure of Fe-Co-Ni spherical particles was able to b
e synthesized from Fe-Co-Ni-Al-Cu precursor films by heating at 600-800 deg
reesC for the phase separation of Fe-Co rich Fe-Co-Ni particles, followed b
y a postheating at 600 degreesC for 5 h. The average size of nanoparticles
was directly determined by the thickness of precursor films. Exchange inter
active hysteresis was observed for the nano-composite (Fe-Co-Ni)+(Fe-Ni-Al)
films resulting from the short exchange interface between ferromagnetic Fe
-Co-Ni particles surrounded by an almost papramagnetic Ni-Al-Fe matrix. Arr
aying the isolated Fe-Co-Ni nanoparticles in a random arrangement on Al2O3
substrate, the particle assembly showed a behavior of dipole interactive fe
rromagnetic clusters depending on their volume and interparticle distance.
(C) 2001 American Institute of Physics.