Synthesis of 0.7BiFeO3-0.3BaTiO3 ceramics : thermal, structural and AC impedance studies

Abstract

In a present paper results of the process of synthesis and study of a perovskite-type solid solution of the chemical composition (1-x)BiFeO3–xBaTiO3 for x=0.3 are reported. Synthesis of 0.7BiFeO3–0.3BaTiO3 (BF–BT) ceramics was carried out according to the solid-phase reaction from the mixture of powders. Simultaneous thermal analysis (STA) and X-ray diffraction method were utilized to study the synthesis of BF–BT ceramics. On the basis of STA analysis the optimum conditions of the thermal treatment were found. BF–BT ceramics was studied in terms of its microstructure (SEM), chemical composition (EDS), crystalline structure (XRD), and dielectric properties (impedance spectroscopy) at room temperature. It was found that dense BF–BT ceramics with a cubic structure of Pm3m space group and desired stoichiometry ( 3%) was fabricated under technological conditions differing in both sintering temperature (T=750 C–850 C) and soaking time (t=2h-40h). It was found that an increase in sintering temperature for T=100 C made it possible to decrease the soaking time 10 times. Impedance spectroscopy was utilized for characterizing dynamical dielectric properties of 0.7BF–0.3BT ceramics. The alternative representation of impedance data in a form of complex plot (Z00 vs. Z0) as well as simultaneous Bode plots (imaginary parts of impedance Z00, admittance Y00, electric modulus M00 and tan versus frequency in a log-log scale) were used for preliminary visual analysis. Kramers-Kronig transform test was utilized for experimental data validation. To analyze the room temperature impedance spectroscopy data complex nonlinear least squares fitting method was used and the data were fitted to the corresponding equivalent circuit consisting of resistors and constant phase elements. Agreement between experimental and simulated data was established.