Giant electrostrictive coefficient of KNN-based lead-free ferroelectrics

Abstract

The development of (K, Na)NbO3 (KNN)-based lead-free materials with excellent piezoelectric properties has become an vital aspects in recent years, based on the environmental friendliness and potential for device. As the typical electromechanical property, the electrostrictive effect is tightly linked to piezoelectric response, which is dominating the market of high-precision actuators. However, the electrostriction behaviors of KNN-based piezoelectric materials have been little studied as yet, evoking the exploration for the electrostrictive effect potential urgently. Here, a typical KNN-based piezoelectric material of (1-x)K0.5Na0.5NbO3-xBi0.5Na0.5ZrO3 (KNN-xBNZ, x = 0.09, 0.10, 0.11) has been concentrated on the enhanced relaxor characteristic due to destroyed ferroelectric long-range orders via introducing high content of BNZ, aiming to strengthen the electrostriction. A giant electrostrictive coefficient (Q33 ∼ 0.067 m4/C2) is achieved in KNN-0.1BNZ materials, nearly three times higher than that of reported Pb(Zr, Ti)O3-based materials, and comparable to some typical BaTiO3-based materials. The optimization of Q33 roots in the co-doped appropriate of Bi3+ and Zr4+ at A or B site, which induces the heterogeneous structure and then limits the range of movement for ions on B site. Significantly, a pretty frequency stability of the remarkable Q33 (>0.054 m4/C2 under the frequency of 1–100 Hz) is revealed, benefiting to application for some commercial fuel injectors’ actuators. This research provides a high-performance electrostrictive material, promoting the research of eco-friendly piezoelectric materials.