■ 일 시 : 2023년 3월 15일(수) 오후 4시
■ 장 소 : W1-1 (2425호 강의실)
■ 연 사 : 윤환희 박사
■ 주 제 : Atomic and electronic structures of local crystalline defects in perovskite stannates studied using analytical STEM
■ 주 관 : 신소재공학과 육종민 교수
■ Abstract :
Atomic and electronic structures of local crystalline defects in perovskite stannates studied using analytical STEM
The past decades have seen the rapid advance of transmission electron microscopy (TEM) techniques from aberration correction of the electron probe for a supreme spatial resolution to development of various spectroscopy detectors for better efficiency and higher energy resolutions. Nowadays, seeing atoms has become a daily routine to electron microscopists, and atomic-scale characterization accompanied by spectroscopic techniques is widely performed to understand the physical and chemical properties of diverse materials. In particular, combination of scanning TEM (STEM) and spectroscopy, which is known as analytical STEM, is an optimal tool to explore atomically resolved crystalline, elemental, chemical, and electronic structures of materials. In this talk, analytical STEM studies on the atomic and electronic structures of local crystalline defects in perovskite BaSnO3 are presented. One-dimensional crystalline defects, dislocations and a new type of metallic line defect, are investigated by analytical STEM and ab initio calculations. Experimental STEM images and the electron energy-loss spectroscopy (EELS) data obtained from the defects are interpreted using the structural relaxation and electronic band structure calculation results. The combined analysis reveals the local atomic configurations and the electronic structures of the atomic-scale defects, which enables us to explain the influence of the defects on the properties of the host BaSnO3. In addition, in-situ TEM study on thermally driven phase transformations between PtxSny alloys are briefly discussed as well.
[ref] H. Yun* , A. Prakash, T. Birol, B. Jalan, K.A. Mkhoyan* , “Dopant segregation inside and outside dislocation cores in perovskite BaSnO3 and reconstruction of the local atomic and electronic structures”, Nano Lett. 21, 43357 (2021); H. Yun, M. Topsakal, A. Prakash, B. Jalan, JS Jeong, T. Birol, KA Mkhoyan* , “Metallic line defect in wide-bandgap transparent perovskite BaSnO3”, Sci. Adv. 7, eabd4449 (2021).
첨부 : 연사 이력서 1부