Dielectric and impedance studies on the double perovskite Ba2BiTaO6

Abstract

High temperature dielectric measurement on rhombohedral Ba2BiTaO6 shows an anomaly at 250 °C where there is a structural transition from the room temperature rhombohedral (R-3) to high temperature cubic (Fm-3m) phase as inferred from the high temperature X-ray diffraction data. Impedance spectroscopic study reveals that the contribution to the electrical response comes from grain as well as from grain boundary. Grain boundary capacitance does not show significant temperature dependence whereas grain capacitance increases with increasing temperature. Both of these conduction processes are similar in nature as indicated from the close value of activation energies as derived from the Arrhenius plot.