We report on the sonochemical synthesis and aging of ferrofluids consisted
of nanosized particles. TEM study reveals that nanoparticles in fresh liqui
ds are round-shaped and have almost uniform particle size distribution cent
ered around 10 nm. During aging, magnetic nanoparticles organize themselves
in clusters of different shape, which depends mainly on the magnetic natur
e of metals in a particular ferrofluid. Magnetization measurements demonstr
ate the change of magnetic signal, as compare to the flesh ferrofluids. (C)
1999 Acta Metallurgica Inc.