Impedance spectroscopy and conduction mechanism of multiferroic Bi0.8(Ba0.9Ca0.1)0.8Fe0.8(Ti0.9Sn0.1)0.8O3

Abstract

Bi0.8(Ba0.9Ca0.1)0.8Fe0.8(Ti0.9Sn0.1)0.8O3 ceramic is synthesized by conventional solid-state reaction method and investigated by structural, Raman spectra, thermal and dielectric properties. It is crystallized in a biphasic system where it is distorted in rhombohedral-to-orthorhombic with R3c and Pnma space group, respectively. Furthermore, the ferromagnetic-paramagnetic phase transition (TN = 623 K) is detected by (DSC) and Raman spectroscopy The electrical properties of this compound have been studied using complex impedance spectroscopy in the 100 Hz–1006 MHz frequency range and temperature range 443–703 K. During its evolution, an anomaly is observed at 623 K, which corresponds to ferromagnetic-paramagnetic transition. Two semi-circles are observed in impedance plot indicating the presence of two relaxation processes in this compound associated with the grain and grain boundary. The relaxation behavior of the grain and grain boundary of the Bi0.8 (Ba0.9Ca0.1)0.8 Fe0.8(Ti0.9Sn0.1)0.8O3 are also obtained from the analyzed electrical modulus data. AC conductivity measured follows the power-law dependence σAC∼ωs typical for charge transport. Therefore, the experimental results are analyzed with various theoretical models. The calculated values of n1 decreased at lower frequencies with temperature, this behavior reveals that the conduction mechanism is correlated with barrier hopping. While the observed minimum in the temperature dependence at higher frequency exponent n2 strongly suggests that tunneling of the large polarons is the dominant transport process.