Center on Nanoenergy Research, State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures; School of Resources, Environment and Materials; Guangxi University, 530004, Nanning, China.
School of Chemistry & Chemical Engineering, Guangxi University, 530004, Nanning, China.
Nat Commun. 2023 Mar 30;14(1):1776. doi: 10.1038/s41467-023-37469-x.
Antiferroelectrics (AFEs) are promising candidates in energy-storage capacitors, electrocaloric solid-cooling, and displacement transducers. As an actively studied lead-free antiferroelectric (AFE) material, NaNbO has long suffered from its ferroelectric (FE)-like polarization-electric field (P-E) hysteresis loops with high remnant polarization and large hysteresis. Guided by theoretical calculations, a new strategy of reducing the oxygen octahedral tilting angle is proposed to stabilize the AFE P phase (Space group Pbma) of NaNbO. To validate this, we judiciously introduced CaHfO with a low Goldschmidt tolerance factor and AgNbO with a low electronegativity difference into NaNbO, the decreased cation displacements and [BO] octahedral tilting angles were confirmed by Synchrotron X-ray powder diffraction and aberration-corrected scanning transmission electron microscopy. Of particular importance is that the 0.75NaNbO-0.20AgNbO-0.05CaHfO ceramic exhibits highly reversible phase transition between the AFE and FE states, showing well-defined double P-E loops and sprout-shaped strain-electric field curves with reduced hysteresis, low remnant polarization, high AFE-FE phase transition field, and zero negative strain. Our work provides a new strategy for designing NaNbO-based AFE material with well-defined double P-E loops, which can also be extended to discover a variety of new lead-free AFEs.
反铁电体（AFE）在储能电容器、电卡固体制冷和位移传感器等领域具有广阔的应用前景。作为一种备受关注的无铅反铁电（AFE）材料，NaNbO 长期以来一直存在铁电（FE）类似的极化-电场（P-E）滞后回线，表现出较高的剩余极化和较大的滞后。受理论计算的启发，提出了一种新的策略来降低氧八面体倾斜角，以稳定 NaNbO 的 AFE P 相（空间群 Pbma）。为了验证这一点，我们巧妙地引入了 Goldschmidt 容忍因子较低的 CaHfO 和电负性差较小的 AgNbO 到 NaNbO 中，通过同步加速器 X 射线粉末衍射和像差校正扫描透射电子显微镜证实了阳离子位移和 [BO] 八面体倾斜角度的降低。特别重要的是，0.75NaNbO-0.20AgNbO-0.05CaHfO 陶瓷表现出 AFE 和 FE 状态之间高度可逆的相变，表现出明确的双 P-E 回线和具有较小滞后、低剩余极化、高 AFE-FE 相变场和零负应变的芽状应变-电场曲线。我们的工作为设计具有明确双 P-E 回线的 NaNbO 基 AFE 材料提供了一种新策略，也可扩展到发现各种新型无铅 AFE。
