Giant Electric Field‐Induced Strain with High Temperature‐Stability in Textured KNN‐Based Piezoceramics for Actuator Applications

Abstract

AbstractLarge‐strain (K,Na)NbO3 (KNN) based piezoceramics are attractive for next‐generation actuators because of growing environmental concerns. However, inferior performance with poor temperature stability greatly hinders their industrialized procedure. Herein, a feasible strategy is proposed by introducing ‐ defect dipoles and constructing grain orientation to enhance the strain performance and temperature stability of KNN‐based piezoceramics. This textured ceramics with 90.3% texture degree exhibit a giant strain (1.35%) and a large converse piezoelectric coefficient d33* (2700 pm V−1), outperforming most lead‐free piezoceramics and even some single crystals. Meanwhile, the strain deviation at high temperature of 100 °C–200 °C is obviously alleviated from 61% to 35% through texture engineering. From the perspective of practical applications, piezo‐actuators are commonly utilized in the form of multilayer. In order to illustrate the applicability on multilayer actuators, a stack‐type actuator consisted of 5 layers of 0.4 mm thick ceramics is fabricated. It can generate large field‐induced displacement (11.6 µm), and the promising potential in precise positioning and optical modulation are further demonstrated. This work provides a textured KNN‐based piezoceramic with temperature‐stable giant strain properties, and facilitates the lead‐free piezoceramic materials in actuator applications.