Structural and electrical properties of Zn1-xNixFe2O4 ferrite

The phase purity, the homogeneity, lattice structure and cell parameters of the Zn1-xNixFe2O4 was checked by XRD technique. The Ni doping effects on the electrical properties in Zn1-xNixFe2O4 was investigated using conductance spectroscopy. When introducing nickel in Zn ferrite, the conductivity of the material increases. This effect disappears at high temperature (T > 600 K). The conductivity spectra can be splitted in three regions. In the first one, the conductivity is frequency independent. In the second region, the conductivity can be described by the omega(n) law. It decreases with increasing frequency in the third region. DC conductivity analysis proves that electronic conduction was dominated by thermally activated Hopping of Small Polaron (SPH) at high temperature and Variable Range Hopping (VRH) at low temperature. For T > T-s, where T-s is the temperature at which appears a change in the slope of sigma T-dc(1000/T) curves, the activation energy decreases when increasing Ni content (from E-a=665 meV for x=0 to E-a = 283 for x=0.5). For all Ni compositions, the activation energy is equal to 280 meV when temperature is lower than T-s. From AC-conductivity study, it is found that activation energy decreases with increasing Ni concentration and varies significantly when increasing frequency. Also, the variation of the exponent "n" confirms that hopping model is the dominating mechanism in the system. (C) 2015 Elsevier B.V. All rights reserved.