Enhanced electromechanical properties of CaZrO 3 -modified (K 0.5 Na 0.5 )NbO 3 -based lead-free ceramics

Pairing of large strain response and high d 33 with high T c in (K 0.5 Na 0.5 )NbO 3 -based materials is of high significance in practical applications for piezoelectric actuators. Here, we report remarkable enhancement in the electromechanical properties for (1-x)(K 0.52 Na 0.48 ) (Nb 0.95 Sb 0.05 )O 3 -xCaZrO 3 (KNNS-xCZ) lead-free ceramics through the construction of a rhombohedral ( R )-tetragonal ( T ) phase boundary. We investigated the correlation between the composition-driven phase boundary and resulting ferroelectric, piezoelectric, and strain properties in KNNS-xCZ ceramics. The KNNS-xCZ ceramics with x=0.02 exhibited a large strain response of 0.23% while keeping a relatively large d 33 of 237pC/N, which was mainly ascribed to the coexistence of R and T phases confirmed by the XRD and dielectric results. It was found that pairing of large strain response and high d 33 in KNN-based materials was achieved. As a consequence, we believe that this study opens the possibility to achieve high-performance lead-free electromechanical compounds for piezoelectric actuators applications.