Influence of temperature on the electric, dielectric and AC conductivity properties of nano-crystalline zinc substituted cobalt ferrite synthesized by solution combustion technique

Abstract

Cobalt–zinc nanoferrites with formulae Co$_{1-x}$ Zn$_{x}$Fe$_{2}$O$_{4}$, where x = 0.0, 0.1, 0.2 and 0.3, have been synthesized by solution combustion technique. The variation of DC resistivity with temperature shows the semiconducting behavior of all nanoferrites. The dielectric properties such as dielectric constant ($\varepsilon$’) and dielectric loss tangent (tan $\delta )$ are investigated as a function of temperature and frequency. Dielectric constant and loss tangent are found to be increasing with an increase in temperature while with an increase in frequency both, $\varepsilon$’ and tan $\delta$, are found to be decreasing. The dielectric properties have been explained on the basis of space charge polarization according to Maxwell–Wagner’s two-layer model and the hopping of charge between Fe$^{2+}$ and Fe$^{3+}$. Further, a very high value of dielectric constant and a low value of tan $\delta$ are the prime achievements of the present work. The AC electrical conductivity ($\sigma _\mathrm{AC})$ is studied as a function of temperature as well as frequency and $\sigma _\mathrm{AC}$ is observed to be increasing with the increase in temperature and frequency.