Effect of Zn Substitution on Structural, Magnetic, and Electric Properties of Ni 1−x Zn x Fe 1.78Al 0.2Gd 0.02 O 4 Nanoparticles

Abstract

Nanostructured Ni 1−xZn xFe 1.78Al 0.2Gd 0.02O4 (x = 0.0, 0.1, 0.3, and 0.5) ferrites have been prepared by citrate precursor method. The samples were characterized by several techniques including X-ray diffraction, FTIR spectroscopy, and magnetic and DC and AC electrical measurements. Rietveld analysis revealed crystallite size ranging from 5.8 to 6.7 nm for all samples with an increase in the lattice parameter upon increasing Zn content. With Zn substitution, the saturation magnetization MS first increases for x = 0.1 then decreases for x ≥ 0.2 indicating variation of cation occupancies upon Zn doping. That behavior of magnetization obeys the Yafet–Kittel (Y–K) model, and canting angles 𝜃Y−K were obtained for all samples. For the formed spinel structure, zinc substitution was found to induce a significant change in the cation distribution being proposed on the basis of the magnetization data and the lattice parameter obtained from the Rietveld analysis, and then confirmed by using theoretically calculated lattice parameter. DC electrical resistivity increases with the Zn content, and for whole samples, it increases with temperature then decreases, exhibiting two different behaviors. Variation of activation energy of electrical conduction was deduced from DC measurements. The effect of Zn content on dielectric properties was fully characterized from the AC measurements.