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Controllable defect driven symmetry change and domain structure evolution in BiFeO3 with enhanced tetragonality

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Abstract

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 controllable defect engineering. This work also provides a pathway to generate large tetragonality (or c/a ratio) that could be extended to other ferroelectric material systems (such as PbTiO3, BaTiO3 and HfO2) which might lead to strong polarization enhancement.

Graphical abstract: Controllable defect driven symmetry change and domain structure evolution in BiFeO3 with enhanced tetragonality

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Publication details

The article was received on 29 Jan 2019, accepted on 05 Apr 2019 and first published on 05 Apr 2019


Article type: Communication
DOI: 10.1039/C9NR00932A
Citation: Nanoscale, 2019, Advance Article

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    Controllable defect driven symmetry change and domain structure evolution in BiFeO3 with enhanced tetragonality

    C. Chen, C. Wang, X. Cai, C. Xu, C. Li, J. Zhou, Z. Luo, Z. Fan, M. Qin, M. Zeng, X. Lu, X. Gao, U. Kentsch, P. Yang, G. Zhou, N. Wang, Y. Zhu, S. Zhou, D. Chen and J. Liu, Nanoscale, 2019, Advance Article , DOI: 10.1039/C9NR00932A

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