Thermally stable piezoelectric properties of (K, Na)NbO3-based lead-free perovskite with rhombohedral-tetragonal coexisting phase

A feasible replacement for lead-based piezoelectric ceramics is desperately required for increasing environmental concerns. Benefiting from the construction of a rhombohedral-tetragonal (R-T) phase boundary, a potential lead-free candidate (Na0.5K0.5)NbO3-(Bi0.5Li0.5)TiO3-BaZrO3 is presented in this study, with a large piezoelectric coefficient d33 of 330 pC/N and a unipolar strain of 0.16% at 4 kV/mm. More importantly, the piezoresponse is extremely thermally stable that the strain can maintain a considerable value of 0.12% at the temperature as high as 190 °C, rendering the current system very promising for piezoelectric actuator applications. The temperature dependent phase structure evolution as well as piezoelectric response is investigated systematically for interpretation of underlying mechanisms.

Graphical abstractA niobate-based lead-free piezoelectric ceramic with outstanding thermal stability is presented by constructing a rhombohedral-tetragonal (R-T) phase boundary. The unipolar strain can maintain 0.12% up to 190 °C. Experimental evidences and phenomenological explanations reveal the importance of phase structure engineering in lead-free piezoelectrics.Download high-res image (220KB)Download full-size image