Understanding Strain‐Induced Phase Transformations in BiFeO 3 Thin Films
- Materials Science and Technology Division Oak Ridge National Lab Oak Ridge TN 37831 USA
- Advanced Photon Source Argonne National Laboratory Argonne IL 60439 USA
- Department of Physics University of Michigan Ann Arbor MI 48109 USA
- Center for Nanophase Materials Sciences Oak Ridge National Lab Oak Ridge TN 37830 USA
Experiments demonstrate that under large epitaxial strain a coexisting striped phase emerges in BiFeO 3 thin films, which comprises a tetragonal‐like ( T ′) and an intermediate S ′ polymorph. It exhibits a relatively large piezoelectric response when switching between the coexisting phase and a uniform T ′ phase. This strain‐induced phase transformation is investigated through a synergistic combination of first‐principles theory and experiments. The results show that the S ′ phase is energetically very close to the T ′ phase, but is structurally similar to the bulk rhombohedral ( R ) phase. By fully characterizing the intermediate S ′ polymorph, it is demonstrated that the flat energy landscape resulting in the absence of an energy barrier between the T ′ and S ′ phases fosters the above‐mentioned reversible phase transformation. This ability to readily transform between the S ′ and T ′ polymorphs, which have very different octahedral rotation patterns and c / a ratios, is crucial to the enhanced piezoelectricity in strained BiFeO 3 films. Additionally, a blueshift in the band gap when moving from R to S ′ to T ′ is observed. These results emphasize the importance of strain engineering for tuning electromechanical responses or, creating unique energy harvesting photonic structures, in oxide thin film architectures.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- AC02-05CH11231; FG02-06ER46273; AC02-06CH11357; AC05-00OR22725
- OSTI ID:
- 1342586
- Alternate ID(s):
- OSTI ID: 1212888; OSTI ID: 1214486; OSTI ID: 1401626
- Journal Information:
- Advanced Science, Journal Name: Advanced Science Vol. 2 Journal Issue: 8; ISSN 2198-3844
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- Germany
- Language:
- English
Web of Science
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