Effects of manufacturing conditions and heating on properties of electrochemically produced magnetite nano-powders

Electrochemical (EC) synthesis of magnetite (Fe3O4) nano-powders of specific characteristics is investigated in the range of current densities of J=200–1000 mA/dm2, and temperatures of T=295–361 K. The obtained powders and their modification upon heating in air and argon atmosphere are examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmition electron microscopy (TEM), laser light scattering particle size distribution measurements, magnetic measurements by Faraday method and SQUID, and measurements of specific electrical resistivity. It has been established that structure, morphology, magnetic and electrical properties of the powders can be adjusted by using adequate EC synthesis conditions, and/or by their subsequent heating in the appropriate atmosphere. The temperature induced magnetite reordering, the magnetite to maghemite (γ-Fe2O3), and the maghemite to haematite (α-Fe2O3) phase transitions were examined, too.