HR: 0830h
AN: S21E-0377    [PDF]
TI: New Experimental Evidence of "Low" Melting Temperatures of Iron
AU: * Boehler, R
EM: boe@mpch-mainz.mpg.de
AF: Max-Planck-Institut fuer Chemie, Postfach 3060, Mainz, 55020 Germany
AB: There is still large disagreement in the properties of iron at core pressures derived from diamond cell experiments, shock compression, and theory. Theoretical estimates of the melting temperatures of iron show considerable disagreement and shock data are in disagreement with regards to the onset of melting and the question of a solid-solid transition near 200 GPa. There is, however, growing agreement on the melting temperatures among diamond cell groups using a variety of different methods to detect melting. In view of recent claims (1) that a possible hcp-bcc transition in iron could have been misinterpreted as melting, we present new evidence of melting at Megabar pressures. Visual observation of motion of molten iron is combined with the microscopic analysis of surface textures. The observed features cannot be explained by solid-solid transitions, clearly demonstrating that indeed melting temperatures were reported in the earlier diamond cell work. New high pressure X-ray measurements on laser-heated iron demonstrate a complex phase behavior which is most likely due to the small differences in the free energies of the various high pressure phases. 1) Belonoshko et al. (2003) Nature 424, 1032.
DE: 3924 High-pressure behavior
SC: Seismology [S]
MN: 2003 Fall Meeting