Magnetic evaluation of nanostructure of gold-iron composite particles synthesized by a reverse micelle method

Iron-gold nanocomposite powder was synthesized by sequential reduction of Fe2+ and AU(3+) in reversed micelles. The UV-Vis absorption spectrometry and magnetic separation experiment indicated that the powder is composed of composite nanoparticle containing both iron and gold. XRD indicated that gold exists as metal, and X-ray absorption near edge structure showed that the magnetic phase was Fe3O4. TEM observation indicated that the nanocomposite was single-nanosized and has a sharp size distribution. The magnetization was measured with a SQUID magnetometer and found to be superparamagnetic. The magnetic moment size was evaluated by fitting the lognormal distribution function and the Langevin function to the magnetization data. These results were discussed taking account of the core-shell structure. (C) 2003 Elsevier B.V. All rights reserved.