Dr. Bin Chen [University of Hawaii, USA]

Title: Pressure-induced structural transition in liquid Fe-Ni-C alloys: Implications for composition and evolution of planetary cores | 压力作用下的液态Fe-Ni-C合金结构变化：行星内核成份及演变的影响

Time: 2:00 - 3:00 PM, Wednesday, November 9, 2016

Place: Conference room 410, HPSTAR (Shanghai)

Host: Dr. Li Zhang & Lin Wang

Abstract

Understanding and modeling of planetary core processes such as dynamo and heat flow via convection in liquid outer cores hinge on the knowledge on properties of liquid iron alloys, which are dictated by their liquid structure. Due to experimental challenges, the measurements of iron liquids alloyed with the lighter elements are severely scarce. In this study, the short-range atomic structures of iron liquids alloyed with nickel and carbon have been investigated up to 7 GPa and 1673 K using multi-angle energy-dispersive X-ray diffraction in a Paris-Edinburgh type large volume press. By analyzing the splitting of the second peak in the pair distribution function (PDF) of the liquids, we found that the Fe-Ni (Fe90Ni10) alloyed with 3 and 5 wt.% carbon underwent a liquid structure transition at ~5 GPa. First-principles molecular dynamics (MD) simulations show that the splitting of the second peak is due to connection schemes of 1, 2 3, 4 atom-sharing with the second nearest neighbors, and the coordination number with face-shared connection increases significantly as a results of the transition, corroborating the experimental observations. The polyamorphic transition in the Fe-Ni-C liquids might be related to a fundamental structural change in liquid Fe alloys and may exist in other Fe-light-element alloys. The understanding of the polyamorphic transition in the Fe alloys could provide insights into the structures and dynamics of the planetary cores.

Biography of the Speaker:

EDUCATION

Ph.D. in Geology, University of Illinois at Urbana Champaign (UIUC) 2004-2009

Dissertation Title: Nature and dynamics of Earth and planetary cores from high-pressure properties of ironrich alloys

Dissertation Advisor: Prof. Jie (Jackie) Li

M.S. in Isotope Geochemistry, University of Science and Technology of China (USTC) 2001-2004

Thesis Title: An oxygen isotope study of some ultrahigh pressure metamorphic rocks in the Sulu terrain and its constraints on fluid activity during exhumation of continental plate

Thesis Advisor: Prof. Yong-Fei Zheng

B.S. in Geochemistry, University of Science and Technology of China (USTC) 1997-2001

Thesis Title: One-dimensional model of oxygen isotope transport and exchange during fluid flow and its applications

Thesis Advisor: Prof. Yong-Fei Zheng

PROFESSIONAL EXPERIENCE

Assistant Researcher, Hawaii Institute of Geophysics and Planetology (HIGP), School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (UHM) 01/2014-present

Tenure-track Assistant Researcher in High-Pressure Mineral Physics, HIGP, UHM

Collaborative Faculty in the Department of Geology and Geophysics, UHM

Research Assistant Professor, Dept. Geology, UIUC, Urbana, IL 03/2013-12/2013

 Serve as Chief Technology Officer at the COMPRES Technology Center (COMPTECH), stationed at the Advance Photon Source of Argonne National Laboratory

Assistant Research Scientist, Dept. Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 12/2011-02/2013

Research Fellow, Dept. Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 5/2011-11/2011

Texaco Postdoctoral Fellow, GPS Division, Caltech, Pasadena, CA 08/2009-4/2011

Postdoctoral Research Associate, Dept. Geology, UIUC, Urbana, IL 05/2009-08/2009

Research Assistant, Dept. Geology, UIUC, Urbana, IL 08/2004-05/2009

Teaching Assistant, Dept. Geology, UIUC, Urbana, IL 2007