Jackson, Jennifer M. and Sturhahn, Wolfgang and Lerche, Michael and Zhao, Jiyong and Toellner, Thomas S. and Alp, E. Ercan and Sinogeikin, Stanislav V. and Bass, Jay D. and Murphy, Caitlin A. and Wicks, June K. (2013) Melting of compressed iron by monitoring atomic dynamics. Earth and Planetary Science Letters, 362 . pp. 143-150. ISSN 0012-821X. http://resolver.caltech.edu/CaltechAUTHORS:20130405-153307407
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We present a novel method for detecting the solid–liquid phase boundary of compressed iron at high temperatures using synchrotron Mössbauer spectroscopy (SMS). Our approach is unique because the dynamics of the iron atoms are monitored. This process is described by the Lamb–Mössbauer factor, which is related to the mean-square displacement of the iron atoms. Focused synchrotron radiation with 1 meV bandwidth passes through a laser-heated ^(57)Fe sample inside a diamond-anvil cell, and the characteristic SMS time signature vanishes when melting occurs. At our highest compression measurement and considering thermal pressure, we find the melting point of iron to be T_M=3025±115 K at P=82±5 GPa. When compared with previously reported melting points for iron using static compression methods with different criteria for melting, our melting trend defines a steeper positive slope as a function of pressure. The obtained melting temperatures represent a significant step toward a reliable melting curve of iron at Earth's core conditions. For other terrestrial planets possessing cores with liquid portions rich in metallic iron, such as Mercury and Mars, the higher melting temperatures for compressed iron may imply warmer internal temperatures.
|Additional Information:||© 2012 Published by Elsevier B.V. Received 25 November 2011. Received in revised form 21 November 2012. Accepted 27 November 2012. Editor: L. Stixrude. Available online 8 January 2013. We thank D.L. Lakstanov for help with experiments, G. Shen, D. Zhang, H.-K. Mao, and P. D. Asimow for helpful discussions, and the NSF and Caltech for support of this research. We thank two anonymous reviewers and the editor, L. Stixrude, for helpful comments and suggestions. Use of the Advanced Photon Source was supported by the U.S. D.O.E., O.S., O.B.E.S. (DE-AC02- 06CH11357). Sector 3 operations are partially supported by COMPRES (NSF EAR 06-49658). SEM and nanoSIMS analyses were carried out at the Caltech GPS Division Analytical Facility (funded in part by the MRSEC Program of the NSF under DMR-0080065).|
|Subject Keywords:||iron; melting; dynamics; high-pressure; Mössbauer|
|Official Citation:||Jennifer M. Jackson, Wolfgang Sturhahn, Michael Lerche, Jiyong Zhao, Thomas S. Toellner, E. Ercan Alp, Stanislav V. Sinogeikin, Jay D. Bass, Caitlin A. Murphy, June K. Wicks, Melting of compressed iron by monitoring atomic dynamics, Earth and Planetary Science Letters, Volume 362, 15 January 2013, Pages 143-150, ISSN 0012-821X, 10.1016/j.epsl.2012.11.048. (http://www.sciencedirect.com/science/article/pii/S0012821X12006747)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||05 Apr 2013 23:03|
|Last Modified:||11 Jun 2015 21:47|
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