学术报告：Physics of two-dimensional material system through the synergistic combination of density functional theory and electron microscopy

报告题目：Physics of two-dimensional material system through the synergistic combination of density functional theory and electron microscopy

报告人：Dr. Junhao Lin (林君浩)，JSPS fellow，National Institute of Advanced Industrial Science and Technology (AIST), Japan

时间：2017年6月23日下午3点

地点：南校园显示材料与技术广东省重点实验室讲学厅

主持人：陈军教授

Abstract:

It is well documented that the structure of a material determines its physical properties. Revealing the structure-property correlations on single atom scale is an indispensable step in engineering the performance of materials with atomic precision. With the development of aberration corrector, scanning transmission electron microscopy (STEM) can now provide single atom imaging and spectroscopy, giving insightful information on the atomic structure and bonding of the material. Complemented by density functional theory (DFT) calculations, the underlying properties of the system can be correlates back to the structures atom-by-atom. In this talk, I will show that the synergistic combination of STEM/EELS with DFT calculations serves as a powerful tool in understanding the physics in novel two-dimensional (2D) material system. Examples include chalcogen vacancy dynamics in 2D transition-metal dichalcogenide (TMD) [1-3], phase transition and structural ordering in telluride TMD [4,5], interlayer fusion in Pd-based noble metal dichalcogenides [6], and etc. Besides, I will discuss our preliminary results on monochromatic EELS and their applications in the newly emerging 1D inorganic perovskite quantum dots, where the optical properties of the materials can now be probed down to a single quantum object [7].

Reference:

[1] Junhao Lin. et al., Nature Nanotechnology, 9, 432 (2014)

[2] Junhao Lin, et al., ACS Nano, 9, 5189 (2015)

[3] Junhao Lin, et al., ACS Nano, 10, 2782 (2016)

[4] Peng Yu, et al., Advanced Materials, 29, 1603991 (2017)

[5] Jiadong Zhou, et al, Advanced Materials, 29, 1603471 (2017)

[6] Junhao Lin, et al., Physical Review Letters, accepted

[7] Junhao Lin, et al., Nano Letters, 16, 7198 (2016)

报告人简历：

林君浩，1986年生，美国田纳西州Vanderbilt大学物理学博士。博士期间在美国橡树岭国家实验室师从周武博士与Sokrates Pantelides教授进行新兴二维材料的结构与性能研究，广泛结合使用高分辨扫描透射电镜和第一性泛函原理计算作为主要研究工具，以第一作者或共同第一作者在Nature Nanotechnology，Nature Materials，Nano Letters等高影响期刊发表重要研究成果。2015年底博士毕业后赴日本继续进行低电压原位扫描透射电镜的博士后研究工作。现任日本学术振兴会研究员（JSPS fellow），在日本国立产业综合研究所Kazu Suenaga教授指导下进行球差纠正扫描透射电镜在二维材料上的应用研究，主要研究方向包括高低温下原子尺度物相变化的原位表征，结合单色仪和球差纠正技术实现高能量和空间分辨率，并通过电子损失能谱探索单原子尺度下的物质的光学特性，以及利用低温低电压低辐照剂量来研究对电子辐照敏感的二维和钙钛矿材料。相关成果已陆续发表在Nano Letters, PRL等高水平期刊上。

Junhao was born in 1986 and obtained his PhD degree on Physics from Vanderbilt University, USA, in 2015. He performed his PhD thesis in Oak Ridge National Lab under the guidance of Prof. Wu Zhou and Prof. Sokrates Pantelides, and was trained in both theoretical density functional theory (DFT) and experimental scanning transmission electron microscopy (STEM), and combine these two techniques synergistically to investigate the structure-property correlations in two-dimensional (2D) materials. He is now a JSPS fellow in AIST, Japan, hosted by Dr. Kazu Suenaga, and continue the research mostly in 2D materials with low-voltage monochromatic S/TEM. His main research direction includes analysis of complex defect structures in materials, in-situ observation of the dynamical processes in structural transition under environmental stimulations, and optical properties of individual quantum object probed by the monochromatic valence electron energy loss spectroscopy (VEELS).