Abstract
Ba0.75Ce0.033Sr0.2Ti0.96Sn0.04O3 ceramic was prepared by solid-state route. X-ray diffraction (XRD) analysis of the compound shows a tetragonal phase with the space group of P4mm at room temperature. The imaginary part of the impedance (Z '') as a function of frequency reveals the presence of relaxation phenomena. Nyquist plots of impedance exhibit a semicircle arcs at different temperatures and an electrical equivalent circuit of (R1//CPE1) - (R2//CPE2) has been purposed to describe the impedance results. The imaginary part of the complex permittivity (epsilon '') and the dielectric factor (tan delta) show a drastic decrease with the frequency. The decrease can be interpreted by the polarization type of Maxwell-Wagner. On the basis of the universal power law of Jonscher, the conductivity can be written as: sigma = sigma(DC) + A omega(n). At low frequencies, the conduction mechanism obeys to SPH model and to the CBH model at high frequencies.