Mapping Octahedral Tilts and Polarization Across a Domain Wall in BiFeO3 from Z-Contrast Scanning Transmission Electron Microscopy Image Atomic Column Shape Analysis

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• 作者：AlbinaY. Borisevich ; Oleg S. Ovchinnikov ; Hye Jung Chang ; Mark P. Oxley ; Pu Yu ; Jan Seidel ; Eugine A. Eliseev ; Anna N. Morozovska ; Ramamoorthy Ramesh ; Stephen J. Pennycook ; Sergei V. Kalinin
• 刊名：ACS Nano
• 出版年：2010
• 出版时间：October 26, 2010
• 年：2010
• 卷：4
• 期：10
• 页码：6071-6079
• 全文大小：530K
• 年卷期：0
• ISSN：1936-086X

文摘

Oxygen octahedral tilts underpin the functionality of a large number of perovskite-based materials and heterostructures with competing order parameters. We show how a precise analysis of atomic column shapes in Z-contrast scanning transmission electron microscopy images can reveal polarization and octahedral tilt behavior across uncharged and charged domain walls in BiFeO₃. This method is capable of visualizing octahedral tilts to much higher thicknesses than phase contrast imaging. We find that the octahedral tilt transition across a charged domain wall is atomically abrupt, while the associated polarization profile is diffuse (1.5−2 nm). Ginzburg−Landau theory then allows the relative contributions of polarization and the structural order parameters to the wall energy to be determined.