Assessment of Strain-Generated Oxygen Vacancies Using SrTiO3 Bicrystals

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• 作者：Si-Young Choi ; Sung-Dae Kim ; Minseok Choi ; Hak-Sung Lee ; Jungho Ryu ; Naoya Shibata ; Teruyasu Mizoguchi ; Eita Tochigi ; Takahisa Yamamoto ; Suk-Joong L. Kang ; Yuichi Ikuhara
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：June 10, 2015
• 年：2015
• 卷：15
• 期：6
• 页码：4129-4134
• 全文大小：431K
• ISSN：1530-6992

文摘

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鈥搗oltage measurements confirm that such oxygen vacancies at the strained boundary result in a decrease of the nonlinearity of the I鈥?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.