Impedance and modulus analysis of barium calcium titanate ferroelectric ceramics

BaTiO3-based derivatives have been explored in recent times for potential applications in energy harvesting and ultrasonics. To this end, energy harvesting and conversion applications require an understanding of the conduction and loss mechanisms. The conduction mechanism in Ba0.9Ca0.1TiO3 (BCT) ceramics is studied using impedance spectroscopy at different temperatures. Impedance analysis suggests the presence of two types of relaxation processes corresponding to grain and grain boundary contributions. The relaxation mechanism follows non-Debye-type behavior. The high resistance of the grain (bulk) in the ferroelectric region does not contribute to the high losses; the losses probably result from the phase transition. In addition, BCT ceramics exhibit a negative temperature coefficient of resistance (NTCR). The open-circuit pyroelectric voltage shows a twofold increase compared to (Ca, Zr) modification in BaTiO3.