报告一：Perspectives of Hydrogen Storage in Aperiodic Ti-based Quasicrystals and High Pressure Research Center in Korea
报告人：Prof. Jaeyong Kim
Department of Physics, and HYU-HPSTAR-CIS High Pressure Research Center, Hanyang University, Seoul, Korea
摘要：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 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 48 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 Hanyang University and a newly established high pressure research center in Seoul.
报告人简介：Jaeyong Kim is Professor of Physics Department at Hanyang University in Seoul, Korea since 2005. After completing Research Associate experience at Brookhaven National Laboratory in 2003, he jointed Pohang Synchrotron Light Source where he constructed a wiggler beamline. His current research area includes structure and dynamics of gas molecules on solid surfaces, formation and application of meta-stable materials, and high pressure physics focused on hydrogen storage at extreme condition. He serves as the director of the High Pressure Research Center at Hanyang University since 2016. The research center is the first organized high pressure dedicated research center in Korea supported by National Research Foundation, and performs an international collaboration with HPSTAR in China and Carnegie Institution for Science in Washington D.C.
报告二：High-Pressure: an unique dimension towards new understanding and applications
摘要：In this talk, I would like to present two progresses we recently made using extreme pressure condition on superconducting hydrogen-rich compound and lithium ion battery material. From a variety of in-situ measurements, it is revealed that phosphine, the recently discovered high pressure superconductor, undergoes two steps of polymerization at high pressure. The final product P4H6 is responsible for the superconductivity, proving a crucial information in understanding the superconducting mechanism of this system. LTO is an important lithium ion battery material with excellent cycling performance. However, it shows poor electronic and ionic conductivity, which limit its application. Our high pressure experiments indicate that the crystalline LTO turns into amorphous under extreme compression and its conductivity is greatly enhanced simultaneously. Theoretical calculations reveale that the amorphous phase induced by high pressure can promote diffusion of Li+ and increase its ionic conductivity by providing ion migration defects. This finding offers a new idea for improving the conductivity of a LTO anode in Li-ion batteries using a high-pressure technique.
报告人简介：“”XScienceNatureReview of Modern PhysicsPhysics Review LettersPNASAdvanced MaterialsSCI90余2200Scientific ReportsAmerican Journal of NanomaterialsJournal of Spectroscopy