Electrochemical synthesis of new magnetic mixed oxides of Sr and Fe: Composition, magnetic properties, and microstructure

An electrochemical method for the preparation of magnetic nanoparticles of new Sr-Fe oxides is presented in this work. It consists of the electrolysis of nitrate or chloride solutions with Sr2+ and Fe3+ salts using commercial Fe electrodes. Magnetic materials are collected as precipitates from nitra te media in the PH range 1-3 and from chloride media within the pH range 1- 12. The presence of 100-300 ppm aniline in acidic nitrate media yields a de crease in energy cost and particle size. Inductively coupled plasma analysi s of materials and energy-dispersive X-ray spectrometry of single particles confirm that they are composed of mixed oxides of Sr and Fe. Al synthesize d materials crystallize as inverse cubic spinels, usually with intermediate structures between magnetite and maghemite. They are formed by nanoparticl es with average sizes from 2 nm to similar to 50 ram, as observed by scanni ng electron microscopy. The electrogenerated mixed oxides have higher satur ation magnetization, but lower remanent magnetization and coercive field, t han commercial strontium hexaferrite with micrometric particle size.