He Liqiang, Zhang Le, Ran Yating, Chen Zibin, Liang Chuanxin, Hao Yanshuang, Li Jianwei, Xu Zhizhi, Yang Sen, Carpenter Michael A, Ren Xiaobing, Wang Dong
Frontier Institute of Science and Technology and School of Physics, State Key Laboratory for Mechanical Behavior of Materials and MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, P. R. China.
Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, UK.
Adv Sci (Weinh). 2025 Jul 11:e02973. doi: 10.1002/advs.202502973.
The miniaturization of domain size via point-defect modification has emerged as an effective strategy for optimizing piezoelectric properties in lead-free ferroelectrics, such as achieving large piezoelectric constants and slim-hysteresis electrostrain through polymorphic nanodomain design. However, this approach is not consistently reliable due to the uncontrollable deceleration of domain wall motion and polarization rotation (i.e., polar dynamics) caused by the random local fields around doping sites. In this work, an innovative strategy is proposed to enhance the polarization and electrostrain responses of nanodomain-patterned ferroelectrics through the design of a strain-enhanced glassy coexistent polar state (SGP), which can be established by incorporating large-radius cation Hf into (BaCa)Bi(TiZrSn)O compositions. The strain-enhanced crossover state between the neighboring glassy tetragonal and orthorhombic domains greatly facilitates overall polar dynamics. This is evidenced by the large dielectric figure of merit ε/tan δ ≈ 9.9×10 with thermal stability up to 23 K, surpassing most of reported lead-free ferroelectric ceramics. Importantly, compared to the initial matrix, significant improvements of 20.8% and 34.2% in maximum polarization and electrostrain amplitude are achieved, while maintaining a minimal polarization/strain hysteresis (≈5%). This work would pave a novel paradigm for designing superior functional ferroics by optimizing the domain dynamics.
通过点缺陷修饰使畴尺寸小型化已成为优化无铅铁电体压电性能的有效策略，例如通过多晶型纳米畴设计实现大压电常数和窄滞后电致应变。然而，由于掺杂位点周围随机局部场导致的畴壁运动和极化旋转（即极化动力学）的不可控减速，这种方法并不总是可靠的。在这项工作中，提出了一种创新策略，通过设计应变增强玻璃态共存极化态（SGP）来增强纳米畴图案化铁电体的极化和电致应变响应，该状态可通过将大半径阳离子Hf掺入（BaCa）Bi（TiZrSn）O组合物中建立。相邻玻璃态四方相和正交相畴之间的应变增强交叉态极大地促进了整体极化动力学。这通过高达23 K热稳定性的大介电品质因数ε/tan δ≈9.9×10得到证明，超过了大多数报道的无铅铁电陶瓷。重要的是，与初始基体相比，最大极化和电致应变幅度分别显著提高了20.
