Prof. Geun Woo Lee [KRISS, South Korea]

Title: Multiple pathways of ice nucleation under dynamic pressure and a liquid-liquid transition of Ti liquid metal

Time: 14:00 ~ 14:45, 16th July

Place: Conference room 410, HPSTAR (Shanghai)

Host: DuckYoung Kim

Polycom: 02120004

Abstract:

Water, due to its unique hydrogen bonds, is one of the materials exhibiting diverse phases in crystals and glasses. In particular, many metastable phases of ice crystals have been reported in various temperature and pressure range. Such metastable phases can be found in supercooled and supercompressed liquid. Dynamic diamond anvil cell (dDAC) combined with piezo-actuator provides an opportunity to rapidly reach the supercompressed regime. Here, we explore pathways of ice crystallization on deeply supercompressed water using dDAC at room temperature. We find that the supercompressed liquid water take various solidification paths detected by high-speed camera images and Raman spectroscopy. There are five different pathways of ice crystallization. We will discuss the detailed paths.

As another topic, we will show a liquid-liquid phase transition (LLPT) with Ti having positive melting slope. This is an interesting phenomenon, since the LLPT has been observed in covalent bonded materials or f-electron materials which have negative or maximum melting slopes. The LLPT of liquid Ti accompanies with diffusion anomaly. The details will be discussed.

Biography of the Speaker:

2007. 4 ~ Present: Principle Researcher, Korea Research Institute of Standards and Science (KRISS)

2009. 9 ~ Present: Professor, Department of Nano Science, University of Science and Technology, South Korea

2004. 12 ~ 2007. 3: Post-doctor at Lawrence Livermore National Laboratory,

- Crystals guest editor (2017)

- Scientific Reports Editor (2015~ now)

- Distinguished Scientist in KRISS