Influence of rare earth ion substitutions on the structural, optical, transport, dielectric, and magnetic properties of superparamagnetic iron oxide nanoparticles

Abstract

Superparamgnetic Fe 3 O 4 and RE:Fe 3 O 4 (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 (NdFeO 3) as a secondary phase in Nd:Fe 3 O 4 sample. The saturation magnetization (s M) 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 c H and remanence r M , indicate the superparamagnetic nature of the investigated samples. The calculated values of indirect optical band gap of Fe 3 O 4 and RE:Fe 3 O 4 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.

Altering the properties of the magnetic Co ferrite nanoparticles fabricated by modified inverse coprecipitation for high-frequency applications

“…All CoZn ferrite have nearly homogeneous nano-size particles with particles size are increasing with increasing Zn 2+ ions. Nature of the surface shows aggregation coalescence character that may be refers to: the surface tension (ST) and magnetic dipoles interactions at the surface [24,34]. It can be also seen in Fig.…”

“…to get fine homogeneity of CoZn ferrites nano-particles. After that the fine powders precipitated and washed for many times with deionized water in order to remove NO 3and Na + ions and salts [24]. Then the washed precursors dried in an oven at 80 O C for one week.…”

“…The data analyzed by the relation: αhν = A(hν − E 4 ) ,/" [24] for near edge absorption. hν is the energy of incident photon, α is the absorbance coefficient,…”

Structural, Dielectric and Magnetic properties of Yttrium doped Hematite Nanoparticle

“…So localized dipoles cannot orient towards field direction or very few may be localised in the field direction and henceshow small value of dielectric constant. This is a general trend exhibited by ionic solids in which more electrons are free and contribute to conduction[41,42].…”

Effect of Anionic Group [SiO4]4-/[PO4]3- on the Luminescence Properties of Dy3+-Doped Tungstate Structural Compounds

“…As an important activator, Dy 3+ ions have been studied in detail in many matrices [24,25]. For scheelite structural matrices, Dy 3+ ions can also be incorporated into the crystal lattice as an effective activator.…”