Probing the Coexistence of Ferroelectric and Relaxor States in Bi0.5Na0.5TiO3-Based Ceramics for Enhanced Piezoelectric Performance.

To tackle the global restriction on the use of lead-based materials, a feasible strategy of developing a piezoelectric ceramic with a ferroelectric- and relaxor-coexisted hybrid state is proposed in order to reduce the energy barrier as well as to assist polarization rotation. A significantly enhanced piezoelectric coefficient, d33, of 173 pC/N along with a broadened high-temperature stability above 300 °C has been obtained. Further probing via piezoresponse force microscopy unveils the grain boundary-governed domain structures with complicated configurations, suggesting close correlations with the coexistence of ferroelectric and relaxor states. This work demonstrates a recipe for establishing a novel grain-based ferroelectric-relaxor hybrid state with improved piezoelectric performance, which can further be beneficial for realistic applications.