Huang Yuntao, Wu Yao, Wu Tiantian, Chen Jianwei, Wang Sijin, Xue Kan-Hao, Fu Zhengqian, Dong Wen, Zheng Ting, Zhang Shujun, Wu Jiagang
College of Materials Science and Engineering, Sichuan University, Chengdu, China.
College of Integrated Circuits & Engineering Research Center for Functional Ceramics Ministry of Education & Wuhan National Laboratory For Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China.
Sci Adv. 2025 Sep 5;11(36):eady5104. doi: 10.1126/sciadv.ady5104.
The pyroelectric effect plays a critical role in thermal imaging and energy harvesting. Despite extensive efforts to enhance performance through doping and composite engineering, the mechanisms underlying defect dipole coupling with phase structures remain poorly understood, impeding the advancement of defect-engineered symmetry modulation. Here, we report an abnormal pyroelectric phenomenon where the pyroelectric coefficient () increases notably when poling temperature exceeds the orthorhombic-to-tetragonal phase transition temperature () in potassium sodium niobate ceramics. The at 200°C ( = 45.4 × 10 C m K) rises more than sevenfold compared to poling within the orthorhombic phase ( = 6.5 × 10 C m K), representing the highest value reported to date and offering benefit for high-temperature thermal sensing. A dual mechanism is proposed, involving rigid-ion displacement and defect dipole alignment, which respectively contribute to increased displacement charge and space charge. Our findings establish a paradigm for optimizing high-temperature pyroelectrics through a simple, symmetry-confined thermal poling.
热释电效应在热成像和能量收集方面起着关键作用。尽管人们通过掺杂和复合工程等方式做出了大量努力来提高性能，但缺陷偶极与相结构耦合的潜在机制仍知之甚少，这阻碍了缺陷工程对称调制的进展。在此，我们报道了一种异常热释电现象，即在铌酸钠钾陶瓷中，当极化温度超过正交相到四方相的相变温度时，热释电系数（）显著增加。在200°C时（= 45.4 × 10 C m K），与在正交相内极化（= 6.5 × 10 C m K）相比，其上升了七倍多，这是迄今为止报道的最高值，对高温热传感有益。我们提出了一种双重机制，涉及刚性离子位移和缺陷偶极排列，它们分别导致位移电荷和空间电荷增加。我们的研究结果建立了一种通过简单的、对称受限的热极化来优化高温热释电材料的范例。
