superparamgnetic iron oxide nanoparticles (SPIONs), rare earth (RE) ions, structure, optical and activation energies, electrical conductivity, dielectric constant, saturation magnetization
Superparamgnetic Fe3O4 and RE:Fe3O4 (RE = Dy, Nd, La) nanoparticles with an average crystallite size in the range of 15–24 nm, were synthesized by co-precipitation method. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), UV–Vis spectroscopy, LCR bridge, and two-probe technique. X-ray diffraction patterns of all the investigated samples reveal the typical phase of magnetite structure, with a small contribution of orthoferrite (NdFeO3) as a secondary phase in Nd:Fe3O4 sample. The saturation magnetization (Ms) of the samples has values in the range from 41.8 to 52.3 emu/g, and decreases with RE ion doping depending on the ionic radius. Negligible values of the coercivity Hc and remanence Mr, indicate the superparamagnetic nature of the investigated samples. The calculated values of indirect optical band gap of Fe3O4 and RE:Fe3O4 nanoparticles are in the range of 0.9–1.25 eV. The dielectric constant of the samples decreases, while their activation energy increases with the increasing of ionic radii of dopants.
Tsinghua University Press
R. M. KERSHI, F. M. ALI, M. A. SAYED. Influence of rare earth ion substitutions on the structural, optical, transport, dielectric, and magnetic properties of superparamagnetic iron oxide nanoparticles. Journal of Advanced Ceramics 2018, 07(03): 218-228.