Piezoelectrics exhibit mechanical strain in response to electrical stimuli and vice versa. A high level of electric-field-induced strain with minimal hysteresis is desired for piezoelectric materials when used as actuators. The past two decades have seen extensive research into lead-free piezoelectrics to replace Pb(Zr,Ti)O₃ and compositional engineering has been demonstrated to be an effective method to tailor their functional properties. Doped (K,Na)NbO₃ (KNN) compositions with elaborate compositional tuning can exhibit enhanced electromechanical properties. However, a balance between enhanced properties and non-toxicity of the dopants should be considered. In this work, we propose to use microstructural engineering to enhance the properties. Based on phase-field simulations, we propose to take advantage of depolarization energies generated by polar-nonpolar interfaces, to increase the contribution of domain wall motion to electric-field-induced strain. Heterogeneous ferroelectric-paraelectric microstructures were introduced into a KNN ceramic via a two-step sintering process. Their presence was characterized by high-resolution transmission electron microscopy. Enhanced reversible domain wall motion was verified by in situ high-energy X-ray diffraction. Electric-field-induced strain is enhanced by 62% and 200% at 25 °C and 150 °C, respectively. Considering lead-free piezoelectrics also represent an emerging class of biomaterials for medical technology, the non-toxicity and biocompatibility of the investigated compositions are examined by in vitro cell viability assays. Our results demonstrate that microstructural engineering is a promising alternative approach to enhance the electric-field-induced strain of lead-free piezoelectrics while maintaining biocompatibility

压电体响应于电刺激表现出机械应变，反之亦然。当用作致动器时，压电材料需要具有最小滞后的高水平电场诱导应变。在过去的二十年里，人们对无铅压电材料进行了广泛的研究，以取代 Pb(Zr,Ti)O ₃并且成分工程已被证明是一种调整其功能特性的有效方法。掺杂 (K,Na)NbO ₃(KNN) 具有精细成分调整的成分可以表现出增强的机电性能。然而，应该考虑掺杂剂的增强特性和无毒性之间的平衡。在这项工作中，我们建议使用微结构工程来增强性能。基于相场模拟，我们建议利用极性-非极性界面产生的去极化能量，增加畴壁运动对电场诱导应变的贡献。通过两步烧结过程将异质铁电-顺电微结构引入 KNN 陶瓷中。它们的存在以高分辨率透射电子显微镜为特征。通过原位验证增强的可逆畴壁运动高能 X 射线衍射。电场诱导应变在 25 °C 和 150 °C 下分别增强了 62% 和 200%。考虑到无铅压电也代表了一类新兴的医疗技术生物材料，所研究的组合物的无毒和生物相容性通过体外细胞活力测定进行检查。我们的研究结果表明，微结构工程是一种有前景的替代方法，可以增强无铅压电材料的电场诱导应变，同时保持生物相容性