LBNL 한인 모임

Abstract: Grain boundary defectstopological defects around grain boundaries (GB)play an essential role in electrical, optical, magnetic, mechanical, and chemical properties of the polycrystalline materials. When the grain size of the materials decreases to the nanometer scale, the grain boundary defects predominantly determine those properties, opening up a variety of new applications. Although researchers have sought ways to study the contribution of specific grain boundary defects to the properties, non-uniformity in grain size and shape and random misorientation between the grains make these tasks challenging. This presentation will first discuss controlling 3D heteroepitaxy of colloidal faceted nanocrystals to grow uniform multiple grains organized into a well-defined geometry which gives a new opportunity for overcoming such limitations from the non-uniformity and randomness. Within the resulting nanocrystals, we will see that three-dimensionally patterned strain field exist in the form of disclinations and dislocations. We will then discuss how we can apply the 3D hetroepitaxy to investigate the effect of microscopic grain geometry on the macroscopic properties. For example, we can obtain a correlation between the GB defects and the catalytic property, because the patterned strain creates exact GB structure in a periodic fashion that serves as the active sites for catalysis. Lastly, we will highlight that the epitaxy-based design principles can significantly extend the library of grain structures in the nanocrystalline materials.  


Biography: Myounghwan Oh is a postdoc working in Paul Alivisatos group at UC Berkeley and is investigating the properties of the grain boundary defects in the nanocrystalline materials through high-precision control of 3D heteroepitaxy. He received his B.S. in Chemical Biological Engineering from Seoul National University (SNU), Korea, followed by a M.S. in Interdisciplinary of Nanoscience and Technology and a Ph.D. in Chemical Biological Engineering. myoung19.jpg

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공지 KSEA Berkeley Chapter 소개 orppaha 2013.07.31 9816
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22 Solid state Li batteries. What is it? and where is it going? (190605 KSEA Berkeley Seminar) file 지미버틀러 2019.06.05 1306
21 2019 Apr. Farewell Dinner for Dr. Shin and Dr. Cho file 지미버틀러 2019.04.11 888
20 Photo-chemistry and -physics of Ir complexes (190410 KSEA Berkeley Chapter Seminar) file 지미버틀러 2019.04.11 927
19 A single-ion conducting borate network polymer as a viable electrolyte for Li-metal batteries (190410 KSEA Berkeley Chapter Seminar) file 지미버틀러 2019.04.11 723
18 Surface and Interfacial Chemistry of Bio-inspired Phenolic Coatings (190213 KSEA Berkeley Chapter Seminar) file 지미버틀러 2019.04.11 684
17 Study on the chemical/electronic structures of organic functional materials by combining photoemission spectroscopy with argon gas cluster ion beam sputtering (181214 KSEA Berkeley Chapter Seminar) file 지미버틀러 2019.04.11 752
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15 2018 Sep. Farewell Lunch for Dr. Kim file 지미버틀러 2019.04.10 878
14 Development of Innovative materials and process technology: 1. Microreactors for Better Chemical Processes 2. Peptide Self-Assembly (180813 KSEA Berkeley Chapter Seminar) file 지미버틀러 2019.04.10 699
13 2018 July Farewell Dinner for Prof. Kim and Prof. Lee file 지미버틀러 2019.04.10 755
12 2018 May Happy Hour file 지미버틀러 2019.04.10 695