HR: 08:45h
AN: V41B-04    [PDF]
TI: Solid-Solid Transitions at High-PT: Implications for the Earth's Core
AU: * Belonoshko, A B
EM: anatoly@fysik.uu.se
AF: Applied Materials Physics, Department of Material Science and Engineering, The Royal Institute of Technology, Stockholm, 10044 Sweden
AU: * Belonoshko, A B
EM: anatoly@fysik.uu.se
AF: Condensed Matter Theory Group, AlbaNova University Center, The Royal Institute of Technology, Stockholm, 10691 Sweden
AU: Ahuja, R
EM: rajeev@fysik.uu.se
AF: Condensed Matter Theory Group, Department of Physics, Uppsala University, Uppsala, 75121 Sweden
AU: Simak, S I
EM: sergeis@fysik.uu.se
AF: Condensed Matter Theory Group, Department of Physics, Uppsala University, Uppsala, 75121 Sweden
AU: Johansson, B
EM: borje@fysik.uu.se
AF: Applied Materials Physics, Department of Material Science and Engineering, The Royal Institute of Technology, Stockholm, 10044 Sweden
AU: Johansson, B
EM: borje@fysik.uu.se
AF: Condensed Matter Theory Group, Department of Physics, Uppsala University, Uppsala, 75121 Sweden
AU: Burakovsky, L
EM: burakov@lanl.gov
AF: Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 United States
AU: Preston, D L
EM: dean@lanl.gov
AF: Applied Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545 United States
AB: Solid-solid (s-s) transtions can be separated in two groups: one pressure (P) induced and second temperature (T) induced. We will call P-induced s-s transitions those which occur on increasing the pressure (normally at low T) and T-induced s-s transitions those which occur on increasing T at a given P. While P-induced s-s transitions comparably easy to detect experimentally, T-induced s-s transitions might occur at such a high T where they might be misinterpreted as melting. This is particularly true if high-PT experiment is not supported by information on the structure of the emerging phase. We will present theoretical results which show that Xe [1], Fe [2], and Mo [3] exhibit T-induced s-s transitions. These transitions are in good agreement with experimental data, which, however, was interpreted as melting. Our results allow us to suggest that the stable phase in the Earth inner core is body centred cubic iron not the hexagonal closed packed phase. This interpretation allows us to dismiss the major controversy between the "low" and "high" iron melting temperatures. Since $bcc$ iron is less dense than $hcp$ iron, the presumable amount of light elements in the core is less than was thought before. The melting temperature of iron in the center of the Earth, when the $bcc$ phase is taken into account, is about 6900 K.\\ 1. A. B. Belonoshko, R. Ahuja, and B. Johansson, Molecular dynamics study of melting and fcc-bcc transitions in Xe. {\it Phys. Rev. Lett.} {\bf87}, 165505 (2001).\\ 2. A. B. Belonoshko, R. Ahuja, and B. Johansson, Stability of the body-centred-cubic phase of iron in the Earth's inner core. {\it Nature} {\bf 424}, 1032 (2003).\\ 3. A. B. Belonoshko, S. Simak, B. Johansson, L. Burakovsky, and D.L. Preston, High-pressure melting of Mo. {\it Phys. Rev. Lett.} (submitted).\\
DE: 3924 High-pressure behavior
DE: 5134 Thermal properties
DE: 5460 Physical properties of materials
DE: 8124 Earth's interior--composition and state (old 8105)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting