Prof. Choong-Shik Yoo visited HPSTAR

Prof. Choong-Shik Yoo, a Professor in the Department of Chemistry of Washington State University(WSU) and in the internationally recognized WSU Institute for Shock Physics visited HPSTAR from May 03 to May 27, 2016.

His research expertise is on novel materials research under extreme environments of pressure, temperature, and chemical composition. His work has utilized static and dynamic high-pressure capabilities coupled with the state-of-the-art laser spectroscopic methods and x-ray diffraction and spectroscopy at the national synchrotron facilities. Prof. Yoo’s current research studies focus on energetic materials and processes, as well as developments of novel high energy density materials, reactive materials, wear-resistive super hard materials, and novel functional nanocomposites and intermetallics.

His pioneered work included using super-high pressures turned XeF₂, a white crystal used to etch silicon conductors to a compact material capable of storing vast amounts of energy, which is called "Ultra-Battery" or “Super battery as Energy-Dense as High Explosives.

Prof. Choong-Shik Yoo delivered serials of five talks about their recent research progress in high science during his visit in HPSTAR.

    1. “Barochemistry in Dense Molecular Solids”. In the first talk, he discussed about the basic principles governing the pressure-induced chemistry (or barochemistry) in dense solids and offer some insights into how to use these chemical concepts to develop yet been discovered novel structures and materials beyond the class of diamond and c-BN.

2. “Combinatory Chemistry in Dense Solid Mixtures”. Yoo described several examples of combinatory reactions in dense solid mixtures (both homogeneous and heterogeneous) in this talk and pointed out several important chemical concepts governing the transformations of dense mixtures, including internal chemical pressure, metastability, miscibility, and kinetics

3.  “High Energy Density Solids. In this talk”, Yoo shown some of their recent research efforts to lower the transition pressures and enhance the stability of recovered products at ambient condition.

4. "High Pressure Kinetics: Pressure-induced solidification of water in dynamic-DAC", he showed a novel developed technique by his group named dynamic-diamond anvil cell (d-DAC), which is capable of precisely controlling the compression rate over a large pressure range. He also presented their recent work on water phase transition utilized this newly developed technique.

5. "Dynamic Response of Solids: Time-resolved x-ray and spectroscopic studies". In this seminar, Yoo described their recent developments of time-resolved (TR) x-ray diffraction and TR spectroscopic/microscopic methods, capable of probing the time-evolution of crystal structures and chemical species of solids, subjected to thermal and mechanical ignitions and undergoing metal combustions and metathesis reactions.

Professor Yoo twice earned the DOE awards (1995 and 2006) for Excellence in Weapons Materials Research. He currently serves as the US Regional Editor for High Pressure Research and is a member of American Chemical Society, American Physical Society, American Geophysics Union, Materials Research Society, and Three Materials Society.