Effect of Divalent / Trivalent Doping on Structural, Electrical and Magnetic Properties of Spinel Ferrite Nanoparticles

Abstract

Five nanosized divalent/trivalent doped spinel ferrites (a) Cu-Zn co-doped nickel ferrite (Ni0.6Cu0.2Zn0.2Fe2O4), (b)Cd-doped cobalt ferrite (Co0.9Cd0.1Fe2O4), (c) Al-doped cobalt ferrite (CoAl0.3Fe1.7O4), (d) Ru-doped cobalt ferrite (CoRu0.04Fe1.96O4), and (e) Ni-doped gamma ferric oxide (Fe2.55Ni0.12 □0.33O4; where □, is Fe vacancy) are synthesized by coprecipitation method. Energy dispersive X-ray (EDS) and ICPES analysis confirm the stoichiometry of the elemental composition of the synthesized materials. The X-ray diffraction pattern (XRD) confirmed the cubic structure with enlarged lattice parameters as compared to undoped compounds. The size and crystalline structure are confirmed by scanning electron micrographs (SEM), transmission electron microscopy (TEM), and Histogram found approx. 18-52nm. Selected area electron diffraction (SAED) pattern exhibited the lattice planes which indicates the particle is crystalline in nature. Electrical conductivity, Seebeck voltage and Hall effect measurements for these samples showed n-type semiconductors. All samples show typical hysteresis behavior with a decrease in saturation magnetization, and an increase in coercivity as compared to respective undoped ferrites. The remanence ratio was found in the range of 0.11 to 0.47 indicating multi-domain structure for all samples except Fe2.55Ni0.12 □0.33O4, which have single domain structure (MR/Ms=0.58). The observed irreversibility of zero-field cooled (ZFC)-field cooled (FC) curve for Fe2.55Ni0.12 □0.33O4, is indicative of ferromagnetism.