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

Large-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 V-K/Na'VO 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 d(33)* (2700 pm V-1), outperforming most lead-free piezoceramics and even some single crystals. Meanwhile, the strain deviation at high temperature of 100 degrees C-200 degrees 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 mu m), 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.

Automated summary

This study proposes a feasible strategy to enhance the strain performance and temperature stability of KNN-based piezoceramics by introducing V-K/Na'VO defect dipoles and constructing grain orientation. The textured ceramics exhibit a giant strain (1.35%) and a large converse piezoelectric coefficient (2700 pm V-1), outperforming most lead-free piezoceramics and even some single crystals. Furthermore, the strain deviation at high temperatures is significantly alleviated through texture engineering. A stack-type actuator fabricated from these ceramics demonstrates promising potential in precise positioning and optical modulation.