Prof. Takuo Okuchi [Institute for Planetary Materials, Okayama University, Japan]

Title: Ultrafast time-resolved analysis of shock-driven structure transformation of forsterite using power laser and XFEL at SACLA

Time: 14:00 - 15:00, Monday May 21, 2018

Place: Conference room 410, HPSTAR (Shanghai)

Host: Toshimori Sekine

Polycom: 02120004

Abstract:

In order to understand shock-compression processes of planetary materials occurred in the early solar system, we are analyzing time-resolved structure evolution of shock-compressed single crystal of forsterite (Mg2SiO4) using power laser and x-ray free electron laser (XFEL) in combination at SACLA, SPring-8. Using this state-of-the-art pump-probe scheme very effective for studying dynamically compressed states of materials, it was demonstrated that forsterite crystal structure was first strongly compressed in one-dimension, then strong shearing of the structure occurred, and finally it started to transform into another structures which are relevant for those observed in the heavily-shocked meteorites. Such structure transformation processes have been first observed in sub-nanosecond timescale at SACLA very recently, which will be presented and discussed here.

Biography of the Speaker:





Ph.D., Tokyo Institute of Technology, Applied Physics, 1998

M. A., Tokyo Institute of Technology, Applied Physics, 1995

B. A., Kyoto University, Geology and Mineralogy, 1993

Graduate Advisor: E. Takahashi

Post-Graduate Advisors: T. Koda, R. J. Hemley, and H. K. Mao

Research Interests: High Pressure Mineral Physics, Crystallography, Neutron Scattering, NMR

Positions Held:

2008-current, Associate Professor, Institute for Study of the Earth's Interior/Institute for Planetary Materials, Okayama University

2006-2007, Research Fellow, Institute for Advanced Research, Nagoya University (Joint Appointment)

2006 Visiting Fellow, Steacie Institution for Molecular Sciences, National Research Council, Canada (Joint Appointment)

2003-2005 Visiting Fellow, Geophysical Laboratory, Carnegie Institution of Washington (JSPS Research Abroad)

1998-2001 PRESTO Research Fellow of Japan Science and Technology Agency (Joint Appointment)

1998-2007 Assistant Professor, Graduate School of Environmental Studies, Nagoya University  

1998 Postdoctoral Research Fellow, Institute of Low Temperature Science, Hokkaido University (JSPS-PD)

1995-1998 Predoctoral Research Fellow (JSPS-DC1)  

Selected Recent Peer-reviewed Publications:

W. P. Hsieh, F. Deschamps, T. Okuchi, J. F. Lin, Effects of iron on the lattice thermal conductivity and dynamics of Earth's deep mantle, Proceedings of the National Academy of Sciences USA, in press

N. Purevjav, T. Okuchi, X.Wang, C. Hoffmann, N. Tomioka, Determination of hydrogen site and occupancy in hydrous Mg2SiO4 spinel by single-crystal neutron diffraction, Acta Crystallographica, 74, B115 (2018).

T. Okuchi, N. Purevjav, N. Tomioka, Quantitative analysis of hydrogen site and occupancy in a deep-earth hydrous mineral by time-of-flight single crystal Laue neutron diffraction (in Japanese) Journal of the Crystallographic Society of Japan, 59, 309 (2017).

N. Tomioka, T. Okuchi, A new high-pressure form of Mg2SiO4 highlighting diffusionless phase transitions of olivine, Scientific Reports, 7, 17351 (2017).

R. Iizuka-Oku, T. Yagi, H. Gotou, T. Okuchi, T. Hattori, A. Sano-Furukawa, Hydrogenation of iron in the early stage of Earth's evolution, Nature Communications, 8, 14096 (2017).