Solvothermal synthesis, characterization and magnetic properties of nearly superparamagnetic Zn-doped Fe3O4 nanoparticles

We report a facile solvothermal method for synthesizing nearly superparamagnetic Zn-doped Fe3O4 nanoparticles with controllable doping concentration. All samples demonstrate a typical spinel structure with small size (less than 20 nm). The Zn ion doping effect on the structure, morphology and magnetism of Fe3O4 nanoparticles have been systematically studied by XRD, TEM, FTIR, XPS and FMR. It is found that the saturation magnetization of Fe3O4 first increases then decreases with increasing Zn doping concentration due to the different site occupation of Zn ions. In contrast, dynamic magnetic measurements demonstrate that the Lande g-factor shows a monotonic increasing trend by the increase of Zn doping concentration.