Preparation of gamma-Fe2O3 Doped with Co2+ and Dy3+ by Sol-Gel Method

摘要

Pure and doped gamma-Fe2O3 nanoparticles were synthesized via Sol-gel method with ferric nitrate nonahydrate, tartaric acid and ethanol as raw materials, and CoCl2, DyCl3 as doping source. The prepared gamma-Fe2O3 and doped gamma-Fe2O3 were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). The effects of cobalt and dysprosium doping amount on structure, morphologies, and magnetic property were studied in detail. It was found when the actual amounts of doped Co2+ and doped Dy3+ reached the value of about 2.30, the saturation magnetization of Co2+ doped gamma-Fe2O3 and Dy3+ doped gamma-Fe2O3 all reached maximum value at 40.73 emu/g and 28.63 emu/g, respectively. When the actual amounts of doped Co2+ and doped Dy3+ continued to increase by more than 2.30, the saturation magnetization of their doped gamma-Fe2O3 all decreased, due to changes in the magnetization direction of doped crystal core originated from the formed "dopant-vacancy solid solution" in doped gamma-Fe2O3. Moreover, the dysprosium doping level of 8.55 led to formation of new soft magnetic and paramagnetic DyFe4,5O6 orthoferrite phase with orthorhombic symmetry.