Zhu Banghua, Zhang Ji, Long Feixiang, Liu Jue, Sanson Andrea, Olivi Luca, Neuefeind Joerg C, Liu Hui, Chen Jun
Beijing Advanced Innovation Center for Materials Genome Engineering, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China.
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, China.
J Am Chem Soc. 2024 Oct 30;146(43):29694-29702. doi: 10.1021/jacs.4c10907. Epub 2024 Oct 19.
The high-entropy strategy has shown potential in advancing the energy-storage performance of dielectric capacitors, offering benefits to a range of electronic and electrical systems. However, designing high-performance high-entropy relaxor ferroelectrics (RFEs) presents challenges due to the unclear correlation between their core effects and local polarization heterogeneity. Here, we demonstrate that by engineering the local lattice distortion, a core effect in high-entropy systems, to manipulate the local polarization configuration, a giant energy density () of 18.7 J cm and high efficiency (η) of 85% can be achieved in (BiK)TiO-based high-entropy bulk RFE ceramics. Atomic-level local structural analysis unveils that the local lattice distortion field can be flattened by introducing ions with less size mismatch. The increase in configurational entropy from 1.54 to 2.06R is associated with a smoother polar displacement vector field and a reduction in the size of polar clusters to several unit-cell sizes with weak coupling. Consequently, a substantial decrease in hysteresis and an enhancement in the breakdown field strength can be obtained, leading to a significant improvement in energy density by over 6 times and efficiency by 3 times. Our research establishes a relationship between local lattice distortion, atomic polar displacement, and energy-storage performance in complex high-entropy systems, providing insights for enhancing energy-storage performance via a local structure design.
高熵策略在提升介电电容器的储能性能方面已展现出潜力，这对一系列电子和电气系统都有益处。然而，由于高性能高熵弛豫铁电体（RFE）的核心效应与局部极化不均匀性之间的关联尚不明确，设计此类材料面临挑战。在此，我们证明，通过调控高熵体系中的核心效应——局部晶格畸变，来操纵局部极化构型，在（BiK）TiO基高熵块状RFE陶瓷中可实现18.7 J/cm³的巨大能量密度（）以及85%的高效率（η）。原子级局部结构分析表明，引入尺寸失配较小的离子可使局部晶格畸变场变平缓。构型熵从1.54R增至2.06R，这与更平滑的极位移矢量场以及极性团簇尺寸减小至几个晶胞尺寸且耦合较弱有关。因此，可使滞后现象大幅减少，击穿场强增强，从而使能量密度显著提高6倍以上，效率提高3倍。我们的研究确立了复杂高熵体系中局部晶格畸变、原子极位移与储能性能之间的关系，为通过局部结构设计提升储能性能提供了思路。
