AC conductivity and mechanism of conduction study of Ba0.2Sr1.8FeMoO6 double perovskite using impedance spectroscopy

The barium-stronium double perovskite Ba0.2Sr1.8FeMoO6 compound have been synthesized by the sol - gel method and characterized by X-ray diffraction (XRD) technique. The title material crystallizes in the monoclinic system with P2(1)/n space group. The dielectric properties, impedance characteristics, and modulus were studied over a range of frequency (200Hz to 5MHz) and temperature (318K-373K). The frequency and temperature dependence of dielectric permittivity, dielectric loss, and electric modulus is studied. The frequency analysis of modulus properties showed a distribution of relaxation times. Conductivity plots against frequency at a higher frequency suggested the response obeying the universal power law. The temperature behavior of the frequency exponents shows that the overlapping large polaron tunneling (OLPT) model is well adapted to this material. The activation energy associated with the impedance relaxation and the electric modulus spectra is close to the activation energy for dc conductivity indicating the similar nature of relaxation and conductivity.