DC resistivity of Ni–Zn ferrites prepared by oxalate precipitation method

Polycrystalline ferrites with general formula Ni1−xZnxFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) were prepared by oxalate precipitation method. The samples were characterized by X-ray diffraction (XRD), IR and scanning electron microscope (SEM) techniques. All compositions show cubic Spinel structure. Lattice constant increases with increase in zinc content, obeying Vegardʹs law. The physical densities are about 98.14% of their X-ray density. Average crystallite size lies in the range 27.59–31.49 nm. Infrared studies show two absorption bands near about 400 cm−1 and 600 cm−1 for octahedral and tetrahedral sites, respectively. The resistivity of all the samples was studied. It is observed that the resistivity of nickel–zinc ferrites prepared by oxalate precipitation method is higher than that prepared by ceramic and citrate precursor method. It is attributed to greater homogeneity and smaller grain size. Activation energy in paramagnetic region is higher than that of ferrimagnetic region.