Magnetic properties of Cr doped Fe3O4 porous nanoparticles prepared through a co-precipitation method using surfactant

Magnetic Cr3+xFe3+2 − xFe2+O4 (0 x 0.1) porous nanoparticles were prepared by the aqueous co-precipitation method. The resulting magnetic nanoparticles were characterized by using an x-ray diffraction (XRD), field enhanced scanning electron microscope (FESEM), transmission electron microscope (TEM), and vibrating sampling magnetometer (VSM). The nitrogen gas adsorption/desorption isotherm showed a microporous structure of the obtained magnetic materials. A rod and round shape of Fe3O4 was observed as using polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB) surfactant, respectively. The Fe3O4 nanoparticles exhibited superparamagnetic properties with easy separation and re-dispersion in solution by using an external magnet. More remarkably, the saturation magnetization (Ms) was enhanced up to 1.2 times for doping Cr3+ into the Fe3O4 lattice. The effect of surfactants and Cr3+ doping concentrations on size and the magnetic properties of Fe3O4 nanoparticles are studied.