Effect of nickel substitutions on some properties of Cu–Zn ferrites

The spinel ferrite system Cu0.8−xZn0.2NixFe2O4; 0.0 ≤ x ≤ 0.8 is prepared by standard ceramic method. X-ray diffraction (XRD) measurements are used for analyzing the composition, lattice parameter, density, porosity and grain size of these compounds. The infrared spectra (IR) obtained at room temperature in the range 400–4000 cm−1 showed two absorption spectra. The high-frequency band (ν1) and low-frequency band (ν2) are assigned to the tetrahedral and octahedral complexes, respectively. The electrical measurements of these ferrites at various compositions were investigated from room temperature up to 650 K in the frequency range (102–105 Hz). The obtained results revealed semiconductor behavior with an increasing nickel concentration with change in the slope at transition temperature Tc. The determined Tc is found to increase with an increasing Ni concentration. The activation energies calculated at the magnetic region are found to decrease with an increasing Ni content. The relation of the universal exponent s with temperature gives evidence for the presence of the large overlap polaron (LOP) hopping conduction mechanism in these compounds. The obtained results of conductivity are explained in light of the hopping conduction occurring at the octahedral B-sites.