The temperature sensitivity of enhanced piezoelectricity in (K,Na)NbO₃ perovskite-based lead-free piezoelectrics is one of the technical bottlenecks impeding practical applications. This work found a recipe that possesses a piezoelectric strain coefficient d₃₃* as high as 600 pm V⁻¹ over a wide temperature range up to 100 °C, which is additionally insensitive against the frequency of an applied electrical field. Electrical property measurement and nanostructure observation revealed that the high performance combining high piezoelectricity and excellent stability benefits from a diffused phase transition (DPT), which is closely associated with the transition from ferroelectric to relaxor behavior induced by the local structural disorder due to the complicated compositional modification. The high-resolution transmission electron microscopy images of Moiré fringes imply the existence of polar nanoregions (PNRs) that are responsible for the relaxor-like electrical behavior in the present materials. The findings and understanding obtained in this work should be valuable for pushing lead-free piezoelectric ceramics towards practical applications.

中文翻译：

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具有局部结构异质性的高性能无铅压电†

（K，Na）NbO ₃钙钛矿基无铅压电材料中增强压电性的温度敏感性是阻碍实际应用的技术瓶颈之一。这项工作找到了一种具有高达600 pm V ^-1的压电应变系数d ₃₃ *的配方。在高达100°C的宽温度范围内，它对施加的电场频率不敏感。电性能测量和纳米结构观察表明，结合了高压电性和出色稳定性的高性能得益于扩散相变（DPT），其与由于复杂的成分导致的局部结构紊乱引起的铁电行为向弛豫行为的转变密切相关修改。莫尔条纹的高分辨率透射电子显微镜图像表明存在极性纳米区域（PNR），该区域负责本材料中类似弛豫的电行为。