Prof. Choong-Shik Yoo [Washington State University, USA]

  Series Lecture IV  

Title: High Pressure Kinetics: Pressure-induced solidification of water in dynamic-DAC

Time: 10:00 - 11:00 AM, Tuesday, May 24, 2016

Place: Auditorium Room 410, Building 6, HPSTAR (Shanghai)

Host: Dr. Ho-Kwang Mao

Abstract:

Beauty of crystal facets and dendrites found in ice flakes and quenched metals has captured one’s imagination as well as fundamental scientific interest in understanding the crystal growth mechanism associated with the roughening-faceting transition, surface instability, and fractal and dendritic pattern formation. The use of external pressure, on the other hand, provides important advantages to study crystal growth such as a faster transmission of pressure than thermal and chemical diffusion, a homogeneous variation of physical and chemical environment, and no significant gravitational convection. As a result, it enables one to observe more fundamental and accurate phenomena of crystal growth that can be readily compared with theoretical expectations. Yet, it has been challenges to precisely control the pressure and the compression rate in both conventional static and dynamic experiments. To remedy this situation, we have developed a novel technique, dynamic-diamond anvil cell (d-DAC), capable of precisely controlling the compression rate over a large pressure range. In this paper, we present the pressure-induced solidification of water observed in d-DAC, exhibiting (i) slow diffusion-controlled two-dimensional fractal growth, (ii) fast interfacial-controlled three-dimensional dendrite growth, (iii) shock crystal growth, and (iv) metastable crystal growth from super-compressed water.

Biography of the Speaker:

Choong-Shik Yoo is a Professor in the Department of Chemistry and in the internationally recognized WSU Institute for Shock Physics. Prior to his arrival at WSU, he worked for nearly 20 years at the Lawrence Livermore National Laboratory where he developed and led a large multi-disciplinary research group in High Pressure Physics. Professor Yoo received his Ph.D in Physical Chemistry in 1986 from UCLA. 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. Dr. 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. 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.