Electrical transport properties of nanocrystalline and bulk nickel ferrite ceramics by complex impedance spectroscopy
Sanjeet Kumar Paswan1#, Lagen Pradhan 2 Manoranjan Kar2 and Lawrence Kumar1
Central University of Jharkhand Ranchi
Nickel ferrite has high electrical resistivity, low eddy current and dielectricvloss. It is considered as good candidate for microwave application. Its electrical properties depends upon the several factors such as method of preparation, grain size etc. In this work, comparative study on the electrical ransport properties of nanocrystalline NiFe2O4 and its bulk counterparts is reported using complex impedance spectroscopy technique.The synthesized sample by citrate sol-gel method has been sintered at two different temperatures 700 and 900°C. The dielectric properties and ac conductivity have been investigated as a function of both frequency and temperature. The frequency dependent dielectric measurement has been analyzed using modified Debye model.The frequency dependent ac conductivity behavior obeys the Jonscher’s power law. The temperature dependence dc conductivity has been analyzed using Arrhenius equation for the determination of activation energy. The variation of loss tangent as a function of temperature at different frequency has been investigated. The real part of impedance decreases monotonically with increase in both temperature and frequency. The conduction due to grain and grain boundary, and mechanism of conduction has been analyzed by Nyquist plots (cole-cole plot). The impedance spectra show two semicircles in the temperature range 550-625 K.The
observed semicircles have been successfully modelled by an equivalent circuit model. The present study provides in- depth understanding of behavior of localized electric charge carriers leading to polarization mechanism.