Synthesis and magnetic properties of monodisperse Fe3O4 nanoparticles

Abstract

We report the high temperature reaction of iron acetylacetonate in phenyl ether in the presence of oleic acid and oleylamine that was used to synthesize monodisperse Fe3O4 nanoparticles. X-ray diffraction profile and high-angle annular dark-field images give evidence of self-assembled arrays with nanoparticle size of 4 nm. Magnetization versus temperature in the temperature range 2.5–160 K was measured in zero-field-cooled and field-cooled experiments and a blocking temperature Tb=20 K was obtained. Above Tb the nanoparticles show superparamagnetic behavior and the magnetization versus field for various temperature follows the Langevin function. M-H curves below Tb indicate the ferromagnetic behavior with Hc=60–400 Oe for temperature T=2.5–18.5 K.