Due to growing concern for the environment and human health, searching for high-performance lead-free piezoceramics has been a hot topic of scientific and industrial research. Despite the significant progress achieved toward enhancing piezoelectricity, further effort should be devoted to the synergistic improvement of piezoelectricity and its thermal stability. This study provides new insight into these topics. A new KNN-based lead-free ceramic material is presented, which features a large piezoelectric coefficient (d₃₃) exceeding 500 pC/N and a high Curie temperature (T_c) of ~200 °C. The superior piezoelectric response strongly relies on the increased composition-induced structural flexibility due to lattice softening and decreased unit cell distortion. In contrast to piezoelectricity anomalies induced via polymorphic transition, this piezoelectricity enhancement is effective within a broad temperature range rather than a specific small range. Especially, the hierarchical domain architecture composed by nano-sized domains along the submicron domains was detected in this material system, which further contributes to the high piezoelectricity.

中文翻译：

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实用的高性能无铅压电：超越多相共存的结构灵活性

由于对环境和人类健康的日益关注，寻找高性能无铅压电陶瓷一直是科学和工业研究的热门话题。尽管在增强压电性方面取得了重大进展，但仍需进一步努力以协同改进压电性及其热稳定性。这项研究为这些主题提供了新的见解。提出了一种新的基于 KNN 的无铅陶瓷材料，其具有超过 500 pC/N的大压电系数 (d ₃₃ ) 和高居里温度 (T _c) ~200 °C。由于晶格软化和减少的晶胞畸变，优异的压电响应强烈依赖于增加的成分诱导的结构灵活性。与通过多晶态转变引起的压电异常相比，这种压电增强在很宽的温度范围内是有效的，而不是在特定的小范围内。特别是，在该材料系统中检测到由纳米尺寸域沿亚微米域组成的分层域结构，这进一步有助于高压电性。