title: Unexpected Trend in Stability of Xe-F Compounds under Pressure Driven by Xe-Xe Covalent Bonds.
abstract: Xenon difluoride is the first and the most stable of hundreds of noble-gas (Ng) compounds. These compounds reveal the rich chemistry of Ng's. No stable compound that contains a Ng-Ng bond has been reported previously. Recent experiments have shown intriguing behaviors of this exemplar compound under high pressure, including increased coordination numbers and an insulator-to-metal transition. None of the behaviors can be explained by electronic-structure calculations with fixed stoichiometry. We therefore conducted a structure search of xenon-fluorine compounds with various stoichiometries and studied their stabilities under pressure using first-principles calculations. Our results revealed, unexpectedly, that pressure stabilizes xenon-fluorine compounds selectively, including xenon tetrafluoride, xenon hexafluoride, and the xenon-rich compound Xe2F. Xenon difluoride becomes unstable above 81 GPa and yields metallic products. These compounds contain xenon-xenon covalent bonds and may form intercalated graphitic xenon lattices, which stabilize xenon-rich compounds and promote the decomposition of xenon difluoride.
authors: State Key Lab of Superhard Materials, Jilin University , Changchun 130012, P. R. China.|College of Physics and Electronic Information, Luoyang Normal University , Luoyang 471022, P. R. China.|Beijing Computational Science Research Center , Beijing 10084, P. R. China.
authors: Feng
authors: F
authors: Peng
authors: Beijing Computational Science Research Center , Beijing 10084, P. R. China.
authors: Jorge
authors: J
authors: Botana
authors: State Key Lab of Superhard Materials, Jilin University , Changchun 130012, P. R. China.
authors: Yanchao
authors: Y
authors: Wang
authors: State Key Lab of Superhard Materials, Jilin University , Changchun 130012, P. R. China.
authors: Yanming
authors: Y
authors: Ma
authors: Beijing Computational Science Research Center , Beijing 10084, P. R. China.|Department of Chemistry and Biochemistry, California State University Northridge, California 91220, United States.
authors: Maosheng
authors: M
authors: Miao