Controllable defect driven symmetry change and domain structure evolution in BiFeO 3 with enhanced tetragonality

作者：Chao Chen, Chang‐An Wang, Xiangbin Cai, Chao Xu, Caiwen Li, Jingtian Zhou, Zhenlin Luo, Zhen Fan, Minghui Qin, Min Zeng, Xubing Lu, Xingsen Gao, Ulrich Kentsch, Ping Yang, Guofu Zhou, Ning Wang, Ye Zhu, Shengqiang Zhou, Deyang Chen, Jun‐Ming Liu · 发表于：Nanoscale · 年份：2019 · DOI：10.1039/c9nr00932a · 被引用次数：34 · 研究领域：Multiferroics and related materials、Ferroelectric and Piezoelectric Materials、Ferroelectric and Negative Capacitance Devices

Defect engineering has been a powerful tool to enable the creation of exotic phases and the discovery of intriguing phenomena in ferroelectric oxides. However, the accurate control of the concentration of defects remains a big challenge. In this work, ion implantation, which can provide controllable point defects, allows us to produce a controlled defect driven true super-tetragonal (T) phase with a single-domain-state in ferroelectric BiFeO3 thin films. This point-defect engineering is found to drive the phase transition from the as-grown mixed rhombohedral-like (R) and tetragonal-like (MC) phase to true tetragonal (T) symmetry and induce the stripe multi-nanodomains to a single domain state. By further increasing the injected dose of the He ion, we demonstrate an enhanced tetragonality super-tetragonal (super-T) phase with the largest c/a ratio of ∼1.3 that has ever been experimentally achieved in BiFeO3. A combination of the morphology change and domain evolution further confirms that the mixed R/MC phase structure transforms to the single-domain-state true tetragonal phase. Moreover, the re-emergence of the R phase and in-plane nanoscale multi-domains after heat treatment reveal the memory effect and reversible phase transition and domain evolution. Our findings demonstrate the reversible control of R-Mc-T-super T symmetry changes (leading to the creation of true T phase BiFeO3 with enhanced tetragonality) and multidomain-single domain structure evolution through controll...