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Strong Premelting Effect in the Elastic Properties of hcp-Fe Under Inner-Core Conditions

Martorell, B; Vocadlo, L; Brodholt, J; Wood, IG; (2013) Strong Premelting Effect in the Elastic Properties of hcp-Fe Under Inner-Core Conditions. Science , 342 (6157) 466 - 468. 10.1126/science.1243651. Green open access

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Abstract

The observed shear-wave velocity VS in Earth’s core is much lower than expected from mineralogical models derived from both calculations and experiments. A number of explanations have been proposed, but none sufficiently explain the seismological observations. Using ab initio molecular dynamics simulations, we obtained the elastic properties of hexagonal close-packed iron (hcp-Fe) at 360 gigapascals up to its melting temperature Tm. We found that Fe shows a strong nonlinear shear weakening just before melting (when T/Tm > 0.96), with a corresponding reduction in VS. Because temperatures range from T/Tm = 1 at the inner-outer core boundary to T/Tm ≈ 0.99 at the center, this strong nonlinear effect on VS should occur in the inner core, providing a compelling explanation for the low VS observed.

Type:Article
Title:Strong Premelting Effect in the Elastic Properties of hcp-Fe Under Inner-Core Conditions
Open access status:An open access version is available from UCL Discovery
DOI:10.1126/science.1243651
Publisher version:http://dx.doi.org/10.1126/science.1243651
Language:English
Additional information:© 2013 The Authors. This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science 342 on 25 October 2013, DOI: 10.1126/science.1243651. PubMed ID: 24114785
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences

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