MSE/BK21PLUS Special Seminar_Prof. Jaekwang Lee

Reference: MSE Professors

Subject: MSE/BK21PLUS Special Seminar_Prof. Jaekwang Lee

신소재공학과/BK21+ 특별세미나

신소재공학과/BK21+연구단에서 특별 세미나를 아래와 같이 개최하오니 대학구성원 여러분들의 많은 참여 바랍니다.

■ 일시: 2015년 04월 03일 (금) 16:00 ~

■ 장소: 공학 1동 202호 멀티미디어 강의실

■ 세미나 주제: Probing Defects using a Combination of Density-Functional Theory and Scanning Transmission Electron Microscope.

■ 초청연사: 이재광 교수 (부산대학교)

■ Host of Seminar: 오상호 교수

■ Date: 2015. 04. 03 (FRI), 16:00 ~

■ Place: BuildingⅠ, Room.202 Multimedia Room

■ Title: Probing Defects using a Combination of Density-Functional Theory and Scanning Transmission Electron Microscope.

■ Speaker: Prof. Jaekwang Lee (Pusan National University)

■ Host of a Seminar: Prof. Sang-Ho Oh

■ Abstract:

The combination of density functional theory (DFT) and scanning transmission electron microscopy (STEM) is a very powerful technique to directly investigate the structure, properties, chemistry and dynamics of defects1-5 in materials. Recently, two-dimensional materials such as graphene, hexagonal boron-nitride, and transition metal dichalcogenides have emerged among the hottest classes of materials owing to their promising properties for future applications. Here we report a direct, atomically-resolved observation of a single Si6 cluster trapped in a graphene nanopore. Though electron beams are known to induce irreversible atomic displacements, we first show that a 60 keV beam induces a reversible, oscillatory, conformational transformation: one of the Si atoms executes a back-and-forth motion between two sites within the Si6 cluster. Secondly, it has been observed that multivacancies in graphene are subject to reconstruction and partial or total filling by diffusing carbon adatoms (also known as the self-healing process). Stabilization of nanopores in graphene for extended periods of time has not yet been achieved. Here, using ab initio molecular dynamic simulation and STEM, we reveal that Si atoms successfully stabilize graphene nanopores by bridging dangling bonds along the perimeter of the pore.

Dept. of MSE / BK21+