Frequency and temperature dependent dielectric properties in the lead free Ba${}_{0.75}$Ce${}_{0.033}$Sr${}_{0.2}$Ti${}_{0.96}$Sn${}_{0.04}$O${}_3$ ceramics

Ba${}_{0.75}$Ce${}_{0.033}$Sr${}_{0.2}$Ti${}_{0.96}$Sn${}_{0.04}$O${}_3$ 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 (ε′′) and the dielectric factor (tan δ) 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:σ=σ${}_{DC}$+Aω${}^n$. At low frequencies, the conduction mechanism obeys to SPH model and to the CBH model at high frequencies.