High resistance and giant permittivity study of Ni 0.4 Zn 0.6 Fe 2 O 4 spinel ferrite as a function of frequency and temperature

The present research work concerns the study of the resistance and of the permittivity of the compound Ni 0.4 Zn 0.6 Fe 2 O 4 spinel ferrite as a function of frequency in a wide temperature range [300 K, 700 K]. The sample was prepared by the solid-state reaction. The X-ray powder diffraction study confirmed the obtention of a single pure phase. Using the impedance spectroscopy, the equivalent electrical circuit of the sample is determined. Thus, two relaxation times were revealed to depend on frequency and temperature. Besides, the variation of the ac conductivity as a function of frequency and temperature was described by the universal power law. The giant resistance evolution as a function of frequency and temperature was studied. Conduction and relaxation processes were found to be thermally activated with an activation energy around 250 meV. The obtained results were interpreted by the model the jump of charge carriers. A gain permittivity around 10 4 was measured over a wide range of temperature and frequency. Its variation as a function of frequency and temperature was explained using the model of Maxwell–Wanger. This study also shows the importance of grains and grain boundaries contributions in this colossal permittivity of this compound. These results make the compound suitable for super capacitor and insulator layer in electronic devices, if a film deposition process will be set up.