Date 2021-04-06 
Time 16:00 
Title Atomic-Level Understanding toward Functionalizing Transition Metal Oxides 

■ 제 목:  Atomic-Level Understanding toward Functionalizing Transition Metal Oxides


 연 사:  최시영 교수 (포스텍 신소재공학과)              


■ 일 시:  2021년 4월 6(화) 오후 4시


■ Host : 정성윤 교수  


■ 참가자 접속정보 (3:50분까지 참가를 부탁드립니다)   

      접속 링크: 

      ID: 808 075 7553

      비밀번호: 2021mse


 Abstract : 


Properties of new functional materials strongly depend on the composition and atomic structure down to the level of single atoms, and thus characterization at the atomic scale has been a key technology in the long range ordered crystals. Scanning transmission electron microscopy (STEM) is an intuitive and powerful tool that can unveil the mysterious materials issues. In this talk, I will introduce two cases to understand the hidden phenomena on an atomic scale using STEM. 


(1) Ferroelectricity in CaTiO3: the oxygen octahedral rotation in CaTiO3 forms a fundamental atomic distortion in perovskite oxides, but only a few patterns are predominantly present at equilibrium. This has restricted the range of possible properties and functions of perovskite oxides, necessitating the utilization of nonequilibrium patterns of octahedral rotation. Designed metastable pattern of octahedral rotation has been recently found to lead to robust the ferroelectricity in CaTiO3 even at room temperature. The deep learning analysis on the atomic structures has been applied to understand the oxygen octahedral pattern and ferroelectricity.


(2) Metal-insulator transition in VO2: vanadium dioxide (VO2), an archetypal correlated oxide, show a metalinsulator transition (MIT) near room temperature and thus it can be regarded as a potential material to realize the metal-insulator transition in our real life. In the recent effort in our group, the variety of VO2 model experiments has been revealed through the intensive collaborations. Our results were obtained through the combination of thin-film synthesis, structural and electrical characterizations, and theoretical modeling, in order to reveal the controllable parameters affecting metal insulator transition in VO2, such as strain, composition, electronic coupling, and structural coupling.