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Thermodynamic stability of Fe/O solid solution at inner-core conditions

Alfè, A; Price, GD; Gillan, MJ; (2000) Thermodynamic stability of Fe/O solid solution at inner-core conditions. Geophysical Research Letters , 27 (16) 2417 - 2420. 10.1029/2000GL011567. Green open access

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Abstract

We present a new technique which allows the fully ab initio calculation of the chemical potential of a substitutional impurity in a high-temperature crystal, including harmonic and anharmonic lattice vibrations. The technique uses the combination of thermodynamic integration and reference models developed recently for the ab initio calculation of the free energy of liquids and anharmonic solids. We apply the technique to the case of the substitutional oxygen impurity in h.c.p. iron under Earth's core conditions, which earlier static ab initio calculations indicated to be thermodynamically very unstable. Our results show that entropic effects arising from the large Vibrational amplitude of the oxygen impurity give a major reduction of the oxygen chemical potential, so that oxygen dissolved in h.c.p. iron may be stabilised at concentrations up a few mol % under core conditions.

Type:Article
Title:Thermodynamic stability of Fe/O solid solution at inner-core conditions
Open access status:An open access version is available from UCL Discovery
DOI:10.1029/2000GL011567
Publisher version:http://dx.doi.org/10.1029/2000GL011567
Language:English
Additional information:Copyright 2000 by the American Geophysical Union
Keywords:Generalized-gradient approximation, High-pressure, First-principles, Earths core, Energy calculations, Iron, Phase, Feo, Temperature
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences
UCL > School of BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
UCL > VP Research

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