Thursday, November 29, 2012

1211.6520 (Qiang Zhu et al.)

Stability of xenon oxides at high pressures    [PDF]

Qiang Zhu, Daniel Y. Jung, Artem R. Oganov, Colin W. Glass, Carlo Gatti, Andriy O. Lyakhov
Xenon, which is quite inert under ambient conditions, may become reactive under pressure. The possibility of formation of stable xenon oxides and silicates in the interior of the Earth could explain the atomspheric missing xenon paradox. Using the ab initio evolutionary algorithm, we predict the thermodynamical stabilization of Xe-O compounds at high pressures (XeO, XeO$_2$ and XeO$_3$ at pressures above 83, 102 and 114 GPa, respectively). Our calculations indicate large charge transfer in these oxides, suggesting that large electronegativity difference and pressure are the key factors favoring the formation of xenon compounds. Xenon compounds in the Earth's mantle, however, cannot directly explain the missing xenon paradox: xenon oxides are unstable in equilibrium with metallic iron in the Earth's lower mantle, while xenon silicates are predicted to spontaneously decompose at all mantle pressures ($<$136 GPa). This does not preclude Xe atoms from being retained in defects of mantle silicates and oxides.
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