Investigation of structural, morphological and electromagnetic properties of scandium doped nickel-copper-zinc ferrites

Abstract

Various polycrystalline Ni0.3Cu0.2Zn0.5ScxFe2-xO4 (x = 0.00, 0.02, 0.04, 0.05 and 0.07) were synthesized by standard solid-state reaction technique. The composition was calcinated at 1173 K and the samples, prepared from these powders, were sintered at 1373, 1423, 1473 and 1523 K for 5 h in air. The result of compositional variation on structural, morphological and electromagnetic properties of Scandium (Sc3+) doped Ni-Cu-Zn ferrites was investigated. The X-ray diffraction measurements confirmed the single-phase cubic spinel structure of these compositions, and no traces of extra peaks corresponding to any unreacted ingredient were found. Lattice constant increases with substitution of Sc3+ in the place of Fe3+. Theoretical density and bulk density decrease with the increase of Sc3+ substitution. Bulk density of Ni0.3Cu0.2Zn0.5ScxFe2-xO4 reaches the maximum value for x = 0.05 sintered at 1423 K. The average grain sizes increase with increasing Sc3+ substitution up to x = 0.05 then it starts to decrease. The real part of initial permeability decreases for x = 0.02, then it increases for x values up to 0.05 after that it decreases again for x = 0.07. The doping of Sc3+ affects the magnetization may be by alteration of the cation distribution. The maximum saturation magnetization is observed 79 Am2/kg for x = 0.05 sintered at 1423 K. At lower frequency range (up to 105 Hz) dielectric constant decreases rapidly with increasing frequency but at higher frequencies (above 105 Hz) it becomes constant and show negligibly small values which is a good agreement with the Maxwell-Wagner model. Dielectric constant and AC resistivity show similar behavior at different frequency ranges. The resistivity mechanism has been explained on the basis of electron hoping between Fe2+ and Fe3+, and it is concluded that at higher concentrations some Sc3+ may possibly occupy A-sites besides a large portion of it going to B-sites, whereas for lower concentrations Sc3+ preferentially occupy B-sites in the Ni-Cu-Zn ferrites system.