具有超高电致伸缩效应的独特四方BaTiO3基弛豫剂的局部结构异质性,Journal of Materials Chemistry A

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具有超高电致伸缩效应的独特四方BaTiO3基弛豫剂的局部结构异质性
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2023-09-29 , DOI: 10.1039/d3ta04557a
Yonghao Yao ₁ , Lu Wang ₁ , Yuanpeng Zhang ₂ , Jue Liu ₂ , Chuanrui Huo ₁ , Hui Liu ₁ , Jun Chen _{1,

3}

Affiliation

弛豫铁电体具有纳米级结构异质性，并表现出优异的电性能。然而，无铅对应物中复杂的局部结构尚未被很好地破译，这阻碍了对结构和性能之间对应关系的理解。_{在此，独特的四方BaTiO 3} -(Bi _0.5 Li _0.5 )TiO ₃的温度依赖性局部结构利用中子全散射研究了具有超高电致伸缩效应的弛豫剂。尽管长程结构经历了四方相变到立方相变，但在 100 至 500 K 温度范围内，局部尺度 1–10 Å 的显着四方畸变持续存在。有趣的是，纳米级的 Li-Bi 簇存在于 Ba 基体中，即使在高于T _{m 的温度下，这些簇也表现出较大的极性位移}。随着温度的升高，观察到局部极化方向逐渐无序，同时自发极化的幅度几乎恒定。人们发现这种现象导致扩散相变期间宏观偏振消失。这些发现有助于更好地理解局部化学异质性在弛豫行为中的作用，并为利用短程化学有序设计弛豫提供了结构基础。

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Local structure heterogeneity in unique tetragonal BaTiO3-based relaxor featuring ultrahigh electrostrictive effect

Relaxor ferroelectrics are characterized by nanoscale structural heterogeneity and show superior electrical properties. However, the complicated local structures in lead-free counterparts are not well deciphered, impeding the understanding of the corresponding relationships between structure and properties. Herein, the temperature-dependent local structures of the unique tetragonal BaTiO₃-(Bi_0.5Li_0.5)TiO₃ relaxor, which presents an ultrahigh electrostrictive effect, were studied using neutron total scattering. Significant tetragonal distortion at the 1–10 Å local scale persisted between 100 and 500 K, despite the long-range structure having undergone a tetragonal to cubic phase transition. Interestingly, nanoscale Li–Bi clusters were indicated to present in the Ba matrix, with these clusters showing large polar displacements even at temperatures above T_m. A gradual disorder in the local polarization direction with increasing temperature was observed, accompanied by a nearly constant magnitude of the spontaneous polarization. This phenomenon was found to lead to a vanishing of macroscopic polarization during the diffuse phase transition. These findings have contributed to a better understanding of the role of local chemical heterogeneity in the relaxor behavior, and have provided a structural foundation for designing relaxors by utilizing short-range chemical ordering.

更新日期：2023-09-29

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