Influence of external electric field on the physical characteristics of lead free BZT- BCT piezoceramic

The electrical poling of piezoceramics is an essential process, to maximize their piezocoefficient prior to applications, which can significantly alter their other physical properties. In this study, the effect of poling on the properties of lead free 0.5Ba(Zr0.2Ti0.8)O-3-0.5(Ba0.7Ca0.3)TiO3 exhibiting large piezocoefficient was investigated. The sample revealed octahedral distortion induced structural transformation upon poling. The impedance spectrum displayed the resonance modes in poled state, where maximum power transmission is feasible. The polarization hysteresis loop exhibited an asymmetry with an internal bias electric field of 41 V/mm due to the field induced orientational defect. The strain measurements revealed 50% enhancement in electrostriction for the sample after poling. Additionally, the sample revealed an incremental change in bandgap due to B-site cationic off-centre displacements induced by the octahedral distortion. Importantly, the poling induced large internal bias field and the near UV bandgap of the sample facilitated the observed large photovoltaic response with giant open circuit voltage of 18 V which could open up an additional application in the fields such as photovoltaic and UV detector for this versatile compound. (C) 2019 Elsevier B.V. All rights reserved.