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

Hoang Duy Nguyen, Trung Dzung Nguyen, Dai Hai Nguyen and Phuong Tung Nguyen

Abstract

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 (M_s) 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