High inverse piezoelectric coefficient achieved in Sr²⁺‐doped KNN‐based lead‐free piezoceramics

High inverse piezoelectric coefficients are crucial for the effective use of piezoelectric ceramics as actuators. In this study, we focused on the design and preparation of (K 0.5− x Na 0.5− x Sr x ) (Nb 0.8 Ta 0.2 )O 3 ( x = 0, 0.01, 0.02, 0.03) by defect engineering and investigated the effect of Sr 2+ doping on its electrical properties. The results showed that a single perovskite phase can be achieved when Sr 2+ doping is less than 3 mol%. Furthermore, Sr 2+ doping was found to cause a linear decrease in both the Curie temperature ( T C ) and the orthorhombic–tetragonal phase transition temperature ( T O‐T ). The ceramic with x = 1% showed optimal piezoelectric properties, exhibiting an electric field‐induced strain of 0.124% under a low driving electric field of 20 kV/cm. This corresponds to an inverse piezoelectric coefficient () of 620 pm/V, which is comparable to that of commercial PZT piezoelectric ceramics. This study not only provides potential piezoelectric ceramics for actuators but also serves as a reference for developing high‐performance piezoelectric ceramics.