Prof. Jaeyong Kim [Hanyang University, Korea]

Title: High Density Hydrogen Storage in TiZrNi Quasicrytals and Perspectives under High Pressure

Time: 10:00 - 11:00 AM, Monday, January 16, 2017

Place: Conference room 410, HPSTAR (Shanghai)

Host: Dr. Bin Chen

Abstract

Although Ti-based quasicrystals are known to uptake a large amount of hydrogen exceeding the density of liquid hydrogen, their reasons for the absorbing mechanism including the diffusion and exact locations of foreign atoms are not clearly understood because of their structural and chemical complexity. Structural complexity includes an inherent relatively short-range atomic ordering and a 5-fold symmetry which is forbidden in the concept of solid state physics. The maximum value of hydrogen loading capacity in Ti53Zr27Ni20 quasicrystals by using a gas-phase loading was near 2.0 wt. %. Theoretical calculation and modeling of their approximant phases predict that a significant amount of interstitial sites are still available for hosting hydrogen.

To realize the prediction, we squeezed TiZrN quasicrystal samples using a diamond anvil cell up to 28 GPa under hydrogen environment and estimated the hydrogen loading amount by analyzing the peak shifts in XRD after hydrogenation. Quasicrystal phase sustained to the applied pressure with uniform shift of the main peaks suggesting that hydrogen atoms diffuse into the interstitials homogeneously without phase transformation. The maximum value of hydrogen loading at 28 GPa was near 4 wt. % with a completely reversible process. The results of hydrogen loading values at high pressures for TiZrNi alloys exhibiting different phases depending on cooling rates will be discussed. Effects of hydrogen on structural stability, electrical conductivity and magnetization values will also be presented with the introduction of a newly established high pressure research center in Korea.

Biography of the Speaker:

Research Interests
•Reactions and structures of gas molecules on metal oxides
•Dynamics and absorptions of hydrogen in complex materials
•Quasicrystals and their applications on hydrogen storage
•Studies of materials under high pressure
•Characterization of metallic thin films
•Construction of the wiggler beamline at Pohang Synchrotron Light Source (PLS-5A)

Professional History
•Mar. 2005 - present: Professor, Department of Physics, Hanyang University, Seoul
•Sept. 2013- present:  Chairperson of the Department of Convergence Nanoscience
•Aug 2016- present:  Director of HYU-HPSTAR-CIS High Pressure Research Center
•Mar. 2011 –Feb. 2012: Visiting scholar, Brookhaven National Laboratory, Upton, NY
•Sept. 2009 –Feb. 2011: Chairperson of the Physics Department, Hanyang University, Seoul
•Feb. 2003- Feb.2005: Physicist, Beamline Division at Pohang Accelerator Laboratory (PAL)
•1999 –2003: Research Associate, Chemistry Department of Brookhaven National Laboratory

Education
· Ph.D. in Physics, Washington University in St. Louis, Missouri, USA, May 1999.
· M.S. in Physics at Southern Illinois University at Edwardsville (SIUE), Illinois, USA, Aug.1993.
· B.S. in Physics at Sogang University, Seoul, Korea, Feb. 1985