Unveiling the Origin of Ultrahigh Piezoelectricity in Sb Doped KNN Based Piezoceramics

Abstract

Substantial progress is made in the past two decades in improving the room-temperature piezoelectric coefficient of lead-free (K, Na)NbO3 (KNN) based ferroelectric ceramics, allowing them to rival commercial lead zirconate titanate. However, within the theoretical framework, the role of key element antimony (Sb) for the enhanced piezoelectricity has not been fully understood. In this work, a combination of machine learning, density function theory calculations, phase-field simulations and scanning transmission electron microscopy are utilized to establish the structure-property relationship of Sb doped KNN ceramics. This results demonstrate that a significant reduction in local ferroelectric distortion at doping site, attributed to the absence of empty d orbitals in the electron configuration of Sb, promotes polarization rotation, and results in enhanced dielectric and thus the piezoelectric properties. This work reveals the atomic-scale mechanisms underlying the high piezoelectric activity induced by Sb, and connects structural changes to electronic configurations, which is expected to facilitate the design of next-generation ferroelectric ceramics.