The progress of next-generation electromechanical devices is substantially reliant upon achieving high electromechanical coupling performance in piezoelectric materials. Here, a local stress regulation strategy is introduced to significantly enhance the overall electromechanical response of lead-free piezoceramics. A remarkable large piezoelectric coefficient (d33) of ∼800 pC N−1 and longitudinal electromechanical coupling factor (k33) of 88% are obtained in (K,Na)NbO3 (KNN)-based textured piezoceramics. From both experimental examinations and theoretical simulation, including phase-field analyses, it is found that the improved piezoelectric performance primarily stems from the stress-induced elastic field aligned with the preferred crystallographic orientation, which constrains the domain size, resulting in nanoscale short-range ordered domain structures. Such structures facilitate the flexible rotation of electric dipoles within coexisting phases due to flattened free energy distribution, thereby leading to the exceptionally large piezoelectric response. This understanding provides valuable guidance for the design of novel lead-free piezoceramics with excellent piezoelectric performance.

中文翻译：

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(K,Na)NbO3 基无铅织构压电陶瓷的超高机电响应


下一代机电设备的进步很大程度上依赖于压电材料实现高机电耦合性能。在这里，引入了局部应力调节策略，以显着增强无铅压电陶瓷的整体机电响应。在(K,Na)NbO3 (KNN)基织构压电陶瓷中获得了~800 pC N−1 的显着大压电系数 (d33) 和 88% 的纵向机电耦合因子 (k33)。从实验检查和理论模拟（包括相场分析）发现，压电性能的改善主要源于与首选晶体取向一致的应力引起的弹性场，这限制了畴尺寸，导致纳米级短程有序域结构。由于平坦的自由能分布，这种结构有利于共存相内电偶极子的灵活旋转，从而导致异常大的压电响应。这一认识为设计具有优异压电性能的新型无铅压电陶瓷提供了宝贵的指导。