Wen Lanji, Wu Xiaojun, Yin Jie, Zhang Yumin, Yang Diyan, Wu Jiagang
College of Materials Science and Engineering, Sichuan University, Chengdu, 610064, P. R. China.
Small. 2024 Jul;20(28):e2307326. doi: 10.1002/smll.202307326. Epub 2024 Feb 28.
Among pyroelectric materials, BiNaTiO (BNT)-based relaxors are particularly noteworthy due to their significant polarization fluctuation near the depolarization temperature (T), resulting in a large pyroelectric response. What has been overlooked is the dynamic behavior of inherent polar structures, particularly the temperature-dependent evolution of polar nanoregions (PNRs), which significantly impacts the pyroelectric behavior. Herein, based on the large pyroelectric response origination (the ferroelectric-relaxor phase transition), the mixed nonergodic and ergodic relaxor (NR+ER) critical state is constructed, which is believed to trigger the easily fluctuating polarization state with excellent pyroelectric response. Composition engineering (with Li, Sr, and Ta) strategically controls the relaxor process and modulates the dynamic behavior of inherent polar structures by the random field effect. The pyroelectric coefficient of more than 1441 µCmK at room temperature (RT), more than 9221 µCmK (RT), and ≈107911 µCmK (T) are achieved in the Li-doped sample, the Sr-doped sample, and the (Li+Ta) co-doped sample, respectively. This work earns the highest RT pyroelectric coefficient in BNT-based relaxors, which is suitable for pyroelectric applications. Furthermore, it provides a strategy for modulating the pyroelectric performance of BNT-based relaxors.
在热释电材料中，基于铋钠钛矿（BNT）的弛豫铁电体尤其值得关注，因为它们在去极化温度（Td）附近存在显著的极化涨落，从而产生较大的热释电响应。然而，人们忽略了固有极性结构的动态行为，特别是极性纳米区域（PNRs）随温度的演变，这对热释电行为有重大影响。在此，基于大的热释电响应起源（铁电-弛豫相变），构建了混合非遍历和遍历弛豫（NR+ER）临界状态，据信它能触发具有优异热释电响应的易波动极化状态。成分工程（通过锂、锶和钽）通过随机场效应策略性地控制弛豫过程并调节固有极性结构的动态行为。在锂掺杂样品、锶掺杂样品和（锂+钽）共掺杂样品中，室温（RT）下的热释电系数分别超过1441 μC/m²K、超过9221 μC/m²K和≈107911 μC/m²K（Td）。这项工作在基于BNT的弛豫铁电体中获得了最高的室温热释电系数，适用于热释电应用。此外，它为调节基于BNT的弛豫铁电体的热释电性能提供了一种策略。
