Preparation and characterization of amorphous nanometre sized Fe3O4powder

Abstract

A method for the preparation of amorphous Fe ₃ O ₄ powder with a particle size of ca. 25 nm is reported. Amorphous Fe ₃ O ₄ powder can be simply synthesized by slowly exposing amorphous Fe powder to the air. The amorphous properties of Fe ₃ O ₄ nanoparticles were characterized by X-ray diffraction, Mössbauer spectroscopy, transmission electron micrography, differential scanning calorimetry and quantum design SQUID magnetization measurements. This amorphous Fe ₃ O ₄ powder is superparamagnetic and its magnetization at room temperature is very low (<1.5 emu g ^-1 ); it crystallizes at 285±15 °C.