Temperature‐Insensitive (K,Na)NbO 3 ‐Based Lead‐Free Piezoactuator Ceramics

Abstract The development of lead‐free piezoceramics has attracted great interest because of growing environmental concerns. A polymorphic phase transition (PPT) has been utilized in the past to tailor piezoelectric properties in lead‐free (K,Na)NbO 3 (KNN)‐based materials accepting the drawback of large temperature sensitivity. Here a material concept is reported, which yields an average piezoelectric coefficient d 33 of about 300 pC/N and a high level of unipolar strain up to 0.16% at room temperature. Most intriguingly, field‐induced strain varies less than 10% from room temperature to 175 °C. The temperature insensitivity of field‐induced strain is rationalized using an electrostrictive coupling to…