Subsurface Oxygen Vacancy Mediated Surface Reconstruction and Depolarization of Ferroelectric BaTiO3 (001) Surface

Abstract The interplay between surface reconstruction and depolarization of ferroelectric oxide surfaces is strongly influenced by oxygen vacancies (VO). Using in‐situ atomic‐resolution electron microscopy imaging and spectroscopy techniques, it is directly observed that a clean BaTiO3 (001) surface...

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Main Authors: Jeehun Jeong, Jaejin Hwang, Yaolong Xing, Zhipeng Wang, Jaekwang Lee, Sang Ho Oh
Format: Article
Language:English
Published: Wiley 2025-04-01
Series:Advanced Science
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Online Access:https://doi.org/10.1002/advs.202412781
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author Jeehun Jeong
Jaejin Hwang
Yaolong Xing
Zhipeng Wang
Jaekwang Lee
Sang Ho Oh
author_facet Jeehun Jeong
Jaejin Hwang
Yaolong Xing
Zhipeng Wang
Jaekwang Lee
Sang Ho Oh
author_sort Jeehun Jeong
collection DOAJ
description Abstract The interplay between surface reconstruction and depolarization of ferroelectric oxide surfaces is strongly influenced by oxygen vacancies (VO). Using in‐situ atomic‐resolution electron microscopy imaging and spectroscopy techniques, it is directly observed that a clean BaTiO3 (001) surface stabilizes into (2 × 1) BaO‐terminated reconstruction during vacuum annealing. This surface reconstruction is achieved with accommodating BaO deficiency and incorporates TiOx adunits. The cooperative atomic rumpling in both the surface and subsurface layers, arranged in a tail‐to‐tail configuration, is stabilized by planar accumulation of VO in the subsurface TiO2 layer. This reduces the net polarization of surface unit cells, contributing to overall depolarization. Under this atomic rumpling, the polarization‐down (P↓) state is energetically favored over the polarization‐up (P↑) state, as the P↓ state requires less atomic relaxation in the bulk layers to achieve dipole inversion at the subsurface. The energetic preference for VO in the subsurface TiO2 layer of the P↓ state is confirmed through calculations of VO formation energy and the energy barrier for surface‐to‐subsurface migration. These findings reveal that the presence of VO in the subsurface layer lifts the degeneracy in the double‐well potential between the P↓ and P↑ states in BaTiO3 (001).
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spelling doaj-art-ad72b25cb10d4eb2840c7f44c75475442025-08-20T03:14:12ZengWileyAdvanced Science2198-38442025-04-011216n/an/a10.1002/advs.202412781Subsurface Oxygen Vacancy Mediated Surface Reconstruction and Depolarization of Ferroelectric BaTiO3 (001) SurfaceJeehun Jeong0Jaejin Hwang1Yaolong Xing2Zhipeng Wang3Jaekwang Lee4Sang Ho Oh5Department of Energy Engineering KENTECH Institute for Energy Materials and Devices Korea Institute of Energy Technology (KENTECH) Naju 58330 Republic of KoreaDepartment of Physics Pusan National University Busan 46241 Republic of KoreaDepartment of Energy Engineering KENTECH Institute for Energy Materials and Devices Korea Institute of Energy Technology (KENTECH) Naju 58330 Republic of KoreaDepartment of Energy Engineering KENTECH Institute for Energy Materials and Devices Korea Institute of Energy Technology (KENTECH) Naju 58330 Republic of KoreaDepartment of Physics Pusan National University Busan 46241 Republic of KoreaDepartment of Energy Engineering KENTECH Institute for Energy Materials and Devices Korea Institute of Energy Technology (KENTECH) Naju 58330 Republic of KoreaAbstract The interplay between surface reconstruction and depolarization of ferroelectric oxide surfaces is strongly influenced by oxygen vacancies (VO). Using in‐situ atomic‐resolution electron microscopy imaging and spectroscopy techniques, it is directly observed that a clean BaTiO3 (001) surface stabilizes into (2 × 1) BaO‐terminated reconstruction during vacuum annealing. This surface reconstruction is achieved with accommodating BaO deficiency and incorporates TiOx adunits. The cooperative atomic rumpling in both the surface and subsurface layers, arranged in a tail‐to‐tail configuration, is stabilized by planar accumulation of VO in the subsurface TiO2 layer. This reduces the net polarization of surface unit cells, contributing to overall depolarization. Under this atomic rumpling, the polarization‐down (P↓) state is energetically favored over the polarization‐up (P↑) state, as the P↓ state requires less atomic relaxation in the bulk layers to achieve dipole inversion at the subsurface. The energetic preference for VO in the subsurface TiO2 layer of the P↓ state is confirmed through calculations of VO formation energy and the energy barrier for surface‐to‐subsurface migration. These findings reveal that the presence of VO in the subsurface layer lifts the degeneracy in the double‐well potential between the P↓ and P↑ states in BaTiO3 (001).https://doi.org/10.1002/advs.202412781depolarizationferroelectricsin‐situ high‐resolution transmission electron microscopyperovskite oxidessurface reconstructions
spellingShingle Jeehun Jeong
Jaejin Hwang
Yaolong Xing
Zhipeng Wang
Jaekwang Lee
Sang Ho Oh
Subsurface Oxygen Vacancy Mediated Surface Reconstruction and Depolarization of Ferroelectric BaTiO3 (001) Surface
Advanced Science
depolarization
ferroelectrics
in‐situ high‐resolution transmission electron microscopy
perovskite oxides
surface reconstructions
title Subsurface Oxygen Vacancy Mediated Surface Reconstruction and Depolarization of Ferroelectric BaTiO3 (001) Surface
title_full Subsurface Oxygen Vacancy Mediated Surface Reconstruction and Depolarization of Ferroelectric BaTiO3 (001) Surface
title_fullStr Subsurface Oxygen Vacancy Mediated Surface Reconstruction and Depolarization of Ferroelectric BaTiO3 (001) Surface
title_full_unstemmed Subsurface Oxygen Vacancy Mediated Surface Reconstruction and Depolarization of Ferroelectric BaTiO3 (001) Surface
title_short Subsurface Oxygen Vacancy Mediated Surface Reconstruction and Depolarization of Ferroelectric BaTiO3 (001) Surface
title_sort subsurface oxygen vacancy mediated surface reconstruction and depolarization of ferroelectric batio3 001 surface
topic depolarization
ferroelectrics
in‐situ high‐resolution transmission electron microscopy
perovskite oxides
surface reconstructions
url https://doi.org/10.1002/advs.202412781
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AT zhipengwang subsurfaceoxygenvacancymediatedsurfacereconstructionanddepolarizationofferroelectricbatio3001surface
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