Synthesis and characterization of superparamagnetic iron nanocomposites by hydrazine reduction

Superparamagnetic iron nanocomposites were synthesized via a modified oxidation-reduction process. Magnetic iron nanoparticles were prepared first with a moderate reducing agent such as hydrazine. Then. iron nanoparticles obtained were modified by nickel ions in aqueous solution to form core-shell structure nanocomposites. The morphology and magnetic properties of iron nanocomposites were examined by transmission electron microscopy (TEM), VSM and SQUID magnetometer. Temperature dependent magnetization and susceptibility data indicate that the nanocomposites are superparamagnetic above 110 K. The diameter of the iron nanocomposites is determined to be about 6 nm from TEM. showing good agreement with the value acquired by Langevin function fit. X-ray diffraction (XRD) was used to investigate the crystal structure of the iron nanocomposites. (C) 2004 Elsevier B.V. All rights reserved.