Stability of xenon oxides at high pressures

TL;DR

This study predicts the formation and stability of xenon oxides at high pressures using ab initio calculations, providing insights into xenon's reactivity deep within Earth’s interior and its potential role in the missing xenon paradox.

Contribution

It introduces the first theoretical prediction of stable xenon oxides at high pressures and analyzes their electronic properties and stability in Earth's mantle conditions.

Findings

Xenon oxides become thermodynamically stable above 83 GPa.

Large charge transfer occurs in these xenon oxides.

Xenon silicates are unstable and decompose at mantle pressures.

Abstract

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 atmospheric missing xenon paradox. Using the ab initio evolutionary algorithm, we predict the thermodynamical stabilization of Xe-O compounds at high pressures (XeO, XeO2 and XeO3 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.