Synergistic role of poling in enhancing structural heterogeneity in perovskite piezoelectrics

Abstract

Local structural heterogeneity is known to enhance the piezoelectric response of perovskite-based ferroelectrics. Here we investigate how this heterogeneity is affected by strong electric fields using dilute doped Eu⁺³ ions as local structural probes. We make use of the extreme sensitivity of the ⁵D₀ → ⁷F₂ hypersensitive transition of Eu⁺³ vis-à-vis the asymmetric distribution of the ligand field around the doped ion to demonstrate that a strong electric field (poling) increases the overall low-symmetry regions on the local length scale in a BaTiO₃ -based lead-free piezoceramic near the P4mm−Amm2 polymorphic phase boundary (PPB). Our study suggests that the mandatory treatment of poling given to a ceramic to make it piezoactive also contributes to the microscopic mechanisms that improve the system's piezo-response.