title: Assessment of Strain-Generated Oxygen Vacancies Using SrTiO₃ Bicrystals.
abstract: Atomic-scale defects strongly influence the electrical and optical properties of materials, and their impact can be more pronounced in localized dimensions. Here, we directly demonstrate that strain triggers the formation of oxygen vacancies in complex oxides by examining the tilt boundary of SrTiO3 bicrystals. Through transmission electron microscopy and electron energy loss spectroscopy, we identify strains along the tilt boundary and oxygen vacancies in the strain-imposed regions between dislocation cores. First-principles calculations support that strains, irrespective of their type or sign, lower the formation energy of oxygen vacancies, thereby enhancing vacancy formation. Finally, current-voltage measurements confirm that such oxygen vacancies at the strained boundary result in a decrease of the nonlinearity of the I-V curve as well as the resistivity. Our results strongly indicate that oxygen vacancies are preferentially formed and are segregated at the regions where strains accumulate, such as heterogeneous interfaces and grain boundaries.
authors.forename: Si-Young
authors.initials: SY
authors.lastname: Choi
authors.forename: Sung-Dae
authors.initials: SD
authors.lastname: Kim
authors.forename: Minseok
authors.initials: M
authors.lastname: Choi
authors.forename: Hak-Sung
authors.initials: HS
authors.lastname: Lee
authors.forename: Jungho
authors.initials: J
authors.lastname: Ryu
authors.affiliation: §Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Shibata
authors.affiliation: ∥Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan.
authors.forename: Teruyasu
authors.initials: T
authors.lastname: Mizoguchi
authors.affiliation: §Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: Eita
authors.initials: E
authors.lastname: Tochigi
authors.affiliation: ⊥Department of Quantum Engineering, Nagoya University, Nagoya 464-8603, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: #Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.
authors.forename: Suk-Joong L
authors.initials: SJ
authors.lastname: Kang
authors.affiliation: §Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ikuhara
keywords: Perovskites; bicrystals; oxygen vacancies; strain engineering