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Temperature of the inner-core boundary of the Earth: Melting of iron at high pressure from first-principles coexistence simulations
 

Summary: Temperature of the inner-core boundary of the Earth: Melting of iron at high pressure from
first-principles coexistence simulations
Dario Alfè*
Department of Earth Sciences and Department of Physics and Astronomy, Materials Simulation Laboratory,
and London Centre for Nanotechnology, UCL, Gower Street, London WC1E 6BT, United Kingdom
Received 11 December 2008; published 11 February 2009
The Earth's core consists of a solid ball with a radius of 1221 Km, surrounded by a liquid shell which
extends up to 3480 km from the center of the planet, roughly half way toward the surface the mean radius of
the Earth is 6373 km . The main constituent of the core is iron, and therefore the melting temperature of iron
at the pressure encountered at the boundary between the solid and the liquid the inner-core boundary ICB
provides an estimate of the temperature of the core. Here I report the melting temperature of Fe at pressures
near that of the ICB, obtained with first-principles techniques based on density-functional theory. The calcu-
lations have been performed by directly simulating solid and liquid iron in coexistence and show that and at a
pressure of 328 GPa iron melts at 6370 100 K. These findings are in good agreement with earlier
simulations, which used exactly the same quantum-mechanics techniques but obtained melting properties from
the calculation of the free energies of solid and liquid Fe.
DOI: 10.1103/PhysRevB.79.060101 PACS number s : 64.70.D , 71.15.Pd, 91.45.Kn
The study of iron under extreme conditions has a long
history. In particular, numerous attempts have been made to
obtain its high-pressure melting properties.1­9

  

Source: Alfè, Dario - Departments of Earth Sciences & Physics and Astronomy, University College London

 

Collections: Physics; Geosciences