Effect of dc electric field on conductivity and giant permittivity of KxTiyNi1−x−yO

Abstract

Activation energies $\left(E_a\right)$ for electrode and grain boundary (GB) conduction are found to be greater than that of the bulk conduction. This implies that both electrode and GB act as two insulating barriers affecting conductivity and dielectric relaxations in ${\mathrm{K}}_x{\mathrm{Ti}}_y{\mathrm{Ni}}_{1-x-y}\mathrm{O}$ . Decrease in $E_a$ for electrode conduction above $T>295\mathrm{K}$ leads to relatively greater loss due to the dc-charge transportation between electrodes and dielectric. The Cole-Cole equation has been modified to explain ${\epsilon }^{\prime }$ over a wide range of frequency $(10–{10}^7\mathrm{Hz})$ . Impedance spectroscopic study has also been employed to distinguish electrode relaxation from GB relaxation.