Aurivillius phase ceramics exhibit significant potential in high-temperature piezoelectric devices due to their high Curie temperature. However, the rapid decrease in electrical resistivity at high temperatures limits their application. In this work, a series of non-equimolar high-entropy piezoelectric ceramics [Ca_xSr_(1–x)/3Ba_(1–x)/3Pb_(1–x)/3]Bi₄Ti₄O₁₅ were designed and prepared via a conventional solid-state method, and the influence of configurational entropy on the microstructure and electrical properties was investigated. The results show that the pure Aurivillius phase was obtained for all compositions. Due to the hysteretic diffusion effect caused by high entropy design, the grain boundary density is effectively increased, leading to a degradation of electrical transport properties. The results of Raman and TEM indicate that disordered structure and various lattice distortions such as edge dislocations, twists, and tilts of oxygen octahedra coexist in high-entropy ceramics, which synergistically contribute to the increase in ceramic electrical resistivity. Consequently, the electrical resistivity at 500 °C increased by 1–2 orders of magnitude, the sample with x = 0.4 exhibits high electrical resistivity (1.18×10⁸ Ω·cm), and also boasts a high piezoelectric coefficient (14 pC/N) and an optimal operating temperature (>550 °C). This work highlights a way to obtain high-performance piezoelectric ceramics with high Curie temperature through the non-equimolar high-entropy composition design.

中文翻译：

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非等摩尔铋层状 [CaxSr（1–x）/3Ba（1–x）/3Pb（1–x）/3]Bi4Ti4O15 高熵陶瓷，居里温度高


Aurivillius 相陶瓷由于其高居里温度，在高温压电器件中表现出巨大的潜力。然而，高温下电阻率的快速下降限制了它们的应用。本工作采用常规固相方法设计制备了一系列非等摩尔高熵压电陶瓷 [Ca_xSr_{（1–x）/3}Ba_{（1–x）/3}Pb_{（1–x）/3}]Bi₄Ti₄O₁₅，并研究了构型熵对微观组织和电学性能的影响。结果表明，所有组合物均获得纯 Aurivillius 相。由于高熵设计引起的磁滞扩散效应，晶界密度有效增加，导致电输运性能下降。拉曼光谱和 TEM 结果表明，高熵陶瓷中存在无序结构和各种晶格畸变，如氧八面体的边缘位错、扭曲和倾斜，它们协同促进了陶瓷电阻率的增加。因此，500 °C 时的电阻率增加了 1-2 个数量级，x = 0.4 的样品表现出高电阻率 （1.18×10⁸ Ω·cm），并且还拥有高压电系数 （14 pC/N） 和最佳工作温度 （>550 °C）。这项工作突出了一种通过非等摩尔高熵成分设计获得高居里温度高性能压电陶瓷的方法。