Room temperature AC impedance and dielectric studies of Bi and Sr doped PrCo0.6Fe0.4O3 perovskites

Abstract

In this study, Bi and Sr doped PrCo0.6Fe0.4O3 perovskites were synthesised by citrate sol-gel auto-combustion method and sintered at 900°C. The X-ray diffraction pattern shows that all compounds have orthorhombic crystal structure with Pbnm space group and a small amount of secondary phase was observed only in the sample with higher Bi content (Pr0.8Bi0.2Co0.6Fe0.4O3). The average grain sizes of the samples were below 400 nm and the corresponding elemental composition was confirmed from EDS spectra. The oxidation states of elements and the presence of oxygen vacancies were obtained from XPS spectra. The vacancies were found to be more in the Sr-doped compound. Finally, from the detailed complex impedance analysis, it was found that the grain boundary resistance is dominant at room temperature. The variation of dielectric properties and AC conductivity with frequency reveals that the relaxation process was due to Maxwell-Wagner type of interfacial polarisation.