FERROMAGNETIC MATERIALS OBTAINED THROUGH ULTRASONICATION. 1. MAGHEMITE/GOETHITE NANOCOMPOSITES

Maghemite (gamma-Fe2O3)/goethite (alpha-FeOOH) composite nanometric particles were prepared through an one-pot synthesis protocol, involving a chemical precipitation process performed under ultrasonication of iron sulfate in an aqueous basic solution. As proved by infrared spectroscopy, X-ray diffraction and electronic microscopy, the resulted ferromagnetic composite is composed of goethite acicular nanoparticles of average diameters less than 10 nm and lengths around or higher than 100 nm, surrounded by maghemite spherical nanoparticles with a diameter less than 100 nm. The composite nanoparticles functionalized with OH groups belonging to goethite showed also good magnetic properties specific to maghemite (the saturation magnetization is varying from 59.6 emu/g at room temperature to 75.5 emu/g at low temperature).