title: Synthesis and stability of xenon oxides Xe2O5 and Xe3O2 under pressure.
abstract: The noble gases are the most inert group of the periodic table, but their reactivity increases with pressure. Diamond-anvil-cell experiments and ab initio modelling have been used to investigate a possible direct reaction between xenon and oxygen at high pressures. We have now synthesized two oxides below 100 GPa (Xe2O5 under oxygen-rich conditions, and Xe3O2 under oxygen-poor conditions), which shows that xenon is more reactive under pressure than predicted previously. Xe2O5 was observed using X-ray diffraction methods, its structure identified through ab initio random structure searching and confirmed using X-ray absorption and Raman spectroscopies. The experiments confirm the recent prediction of Xe3O2 as a stable xenon oxide under high pressure. Xenon atoms adopt mixed oxidation states of 0 and +4 in Xe3O2 and +4 and +6 in Xe2O5. Xe3O2 and Xe2O5 form extended networks that incorporate oxygen-sharing XeO4 squares, and Xe2O5 additionally incorporates oxygen-sharing XeO5 pyramids. Other xenon oxides (XeO2, XeO3) are expected to form at higher pressures.
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Dewaele
authors.affiliation: TCM Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Worth
authors.affiliation: Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK.|Department of Materials Science &Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK.|Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan.
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Pickard
authors.affiliation: TCM Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Needs
authors.affiliation: European Synchrotron Radiation Facility, BP220, 38043 Grenoble Cedex, France.
authors.forename: Sakura
authors.initials: S
authors.lastname: Pascarelli
authors.affiliation: European Synchrotron Radiation Facility, BP220, 38043 Grenoble Cedex, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Mathon
authors.affiliation: European Synchrotron Radiation Facility, BP220, 38043 Grenoble Cedex, France.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Mezouar
authors.affiliation: Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577, Japan.|Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8500, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Irifune