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Soft X-ray STXM & Ptychography: Imaging chemical phases and dynamics

Speaker

Prof. Young-Sang Yu, Department of Physics, Chungbuk National University

Education

- Feb. 2012  Seoul National University, Seoul, South Korea: 

                 Ph.D. in Material Science & Engineering. (Advisor: Prof. Sang-Koog Kim)

                 Thesis: Gaussian-Pulse-Induced Magnetic Vortex Dynamics in Ferromagnetic Nanostructures.

- Mar. 2003 ~ Jan. 2012  Seoul National University, Seoul, South Korea: 

                                    M.S. & Ph.D. course in Materials Science & Engineering.

- Mar.1998 ~ Feb. 2003  Seoul National University, Seoul, South Korea: 

                                  B.S. in Materials Science & Engineering.

PROFESSIONAL EXPERIENCES

- Sep. 2021 ~ Present  Assistant professor, Chungbuk National University, Department of Physics.

- Oct. 2015 ~ Aug. 2021  Physicist / Beamline Scientist (Beamline 5.3.2.2, 11.0.2.2 & 7.0.1.2), Advanced Light Source, Lawrence Berkeley National Laboratory.

- Jul. 2014 ~ Sep. 2015  Advanced Light Source Collaborative Postdoctoral Fellow, Advanced Light Source, Lawrence Berkeley National Laboratory, Department of Chemistry, University of Illinois at Chicago.

- Nov. 2012 ~ Jun. 2014  Joint Postdoctoral Fellow, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Department of NanoEngineering, University of California San Diego.

- Mar. 2012 ~ Oct. 2012  Postdoctoral Fellow, Nanospinics Laboratory, Seoul National University.

| Date | Thursday, September 23rd, 2021

| Time | 10:00 ~ 11:00

| Venue | 온라인 강의 ( https://snu-ac-kr.zoom.us/j/89656456434?pwd=UlFrLzZMZitGN05BbEtGQm9JclAvZz09) 

             회의 ID: 896 5645 6434

             암호: 865917

Abstract

Techniques capable of dynamic imaging of chemical states at high spatial resolution are essential for elucidating the complex phenomena at the nanoscale that underpin materials’ properties. These observations must occur at multiple scales, but are particularly critical at the single particle level, where incomplete reactions and failure at the crucial length and time scales are prone to occur. For example, battery function is determined by the efficiency and reversibility of the electrochemical phase transformations at solid electrodes, creating the need to accurately define relationships between chemistry, mechanics and morphology far from equilibrium. Conventional transmission X-ray microscopy is an ideal probe of these spatial and temporal dynamics and have been developed to elucidate the physics underlying and transitions between chemical phases. In turn, the spatial resolution of X-ray microscopes has been limited by the quality of Fresnel zone plates used to focus X-rays until the development of diffractive imaging methods. Ptychographic imaging techniques combined with spectral sensitivity, which are adopted at the COherent Scattering and MICroscopy (COSMIC, BL 7.0.1.2) beamline, ideally can resolve nanoscale chemical and morphological features and interactions while following real-time kinetics, revealing how chemical processes evolve and materials function. 

In this talk, I will present recent accomplishments to adapt scanning transmission X-ray microscopy & ptychographic imaging to investigate chemical/mechanical evolution of energy materials. The main objectives are explored and develop a multimodal, multidimensional, and multilength scale methodology to follow the chemical and microstructural evolution at the nanoscale. On the scale of a single particle, we have measured chemical phase distribution and propagation as a function of state-of-charge as well as temperature, illustrating our ability to spatiotemporally resolve the dynamics of the Li intercalation in battery particles. Furthermore, we have demonstrated the highest resolution X-ray images ever recorded in both 2 and 3 dimensions with spectral sensitivity. Our efforts for demonstration of multidimensional, multilength scale, and multimodal visualizations will allow spectro-microscopy with faster data acquisition rates in ALS-U to perform dynamic 3D measurements over larger field-of-view, with higher spatial resolution, under specific sample environments, such as varying temperature, applied voltage, or other-directed influences.

| Host | Prof. Sang-Koog Kim (880-5854)