J. Phys.: Condens. Matter 21 (11 November 2009) 452205 (4pp) doi: 10.1088/0953-8984/21/45/452205
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Stable phases of iron at terapascal pressures
Chris J Pickard1 and R J Needs2
1 Department of Physics and Astronomy, University College London, Gower Street,
London WC1E 6BT,
UK
2 Theory of Condensed Matter Group, Cavendish Laboratory, J J Thomson Avenue,
Cambridge CB3 0HE,
UKAbstract.
We have used density-functional-theory methods to study phases of iron at terapascal (TPa)
pressures. Hexagonal-close-packed (hcp) iron is stable from below 0.1 TPa to multi-TPa
pressures, where we find a window of 7–21 TPa in which the face-centred-cubic (fcc) phase is
slightly more stable. At 34 TPa we find a transition to a body-centred-tetragonal (bct)
phase, which is a small distortion of the body-centred-cubic (bcc) structure. The bcc phase
also becomes more stable than the hcp above 35 TPa. The bct and bcc phases become
considerably more stable than hcp and fcc at even higher pressures, and we expect this
result to hold at high temperatures.
Print publication: Issue 45 (11 November 2009)Received 6 August 2009, in final form 5 October 2009
Published 21 October 2009
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