Superionic to superionic phase change in water: consequences for the interiors of uranus and neptune

Using density functional molecular dynamics free energy calculations, we show that the body centered cubic (bcc) phase of superionic ice previously believed to be the only phase is, in fact, thermodynamically unstable compared to a novel phase with oxygen positions in face centered cubic lattice sit...

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Bibliographic Details
Published in:Physical review letters 2013-04, Vol.110 (15), p.151102-151102, Article 151102
Main Authors: Wilson, Hugh F, Wong, Michael L, Militzer, Burkhard
Format: Article
Language:English
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Summary:Using density functional molecular dynamics free energy calculations, we show that the body centered cubic (bcc) phase of superionic ice previously believed to be the only phase is, in fact, thermodynamically unstable compared to a novel phase with oxygen positions in face centered cubic lattice sites. The novel phase has a lower proton mobility than the bcc phase and may exhibit a higher melting temperature. We predict a transition between the two phases at a pressure of 1±0.5  Mbar, with potential consequences for the interiors of ice giants such as Uranus and Neptune.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.110.151102