Pohang University of Science and Technology · Materials Science
Si-Yong Choi 교수의 연구실은 전자현미경을 활용한 원자해상도 분석을 바탕으로 복잡한 산화물 표면의 구조적 재구성과 비등방성 거동을 규명하고 있습니다. 특히 티타니아, 칼슘지르코네이트계 페로브스카이트, 스트론티타나이트 등 다양한 산화물 재료에서의 잠재적 결함, 비등방성 변형, 산소 공석 형성 기전을 원자 차원에서 규명하고 있습니다. 전기장에 의한 극대적 기계적 변형과 결함의 상호작용 메커니즘을 밝혀내는 데 초점을 두고 있으며, 이는 고성능 센서 및 액추에이터 소자 개발에 기여하고 있습니다.
Figures are computed from collected data and may differ slightly.
Determining the atomic structures of oxide surfaces is critical for understanding their physical and chemical properties but also challenging because the breaking of atomic bonds in the formation of the surface termination can involve complex reconstructions. We used advanced transmission electron microscopy to directly observe the atomic structure of reduced titania (TiO2) (110) surfaces from directions parallel to the surface. In our direct atomic-resolution images, reconstructed titanium atom
We demonstrate that an exceptionally large strain can be induced in CaZrO3-modified alkaline-niobates by electric fields. The maximum induced strain of our niobate-based ceramics could reach more than 1,000 pm/V, which is a much higher value than that of commercial soft PZT ceramics. Atomic-scale annular bright-field (ABF) and annular dark-field (ADF) scanning transmission electron microscopy (STEM) directly revealed that individual single grains were composed of an electrically duplex core–shel
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 disl
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