Enhanced piezoelectricity and temperature stability in LaFeO 3 ‐modified KNN‐based lead‐free ceramics

(0.96‐ x )K 0.48 Na 0.52 NbO 3 ‐0.04Bi 0.5 Na 0.5 ZrO 3 ‐ x LaFeO 3 ceramics (abbreviated as KNN‐BNZ‐LF1000 x ) with enhanced piezoelectric performance and temperature stability were prepared by the conventional solid‐state sintering method. It was found that the incorporation of LaFeO 3 gradually shifted the O‐T phase boundary toward room temperature, while maintaining the Curie temperature above 300°C. The optimal piezoelectricity was found at x  = 0.006, with relatively high piezoelectric constant d 33 of 345 pC/N as well as a high level of unipolar strain (0.126% at 3 kV/mm). Benefiting from the diffused phase transition induced by appropriate amount of LaFeO 3 content, the KNN‐BNZ‐LF6 sample possessed greatly enhanced the temperature stability of d 33 ∗ , which varied less than 8% in the temperature range of 20°C‐100°C.