New high-pressure van der Waals compound Kr(H2)4 discovered in the krypton-hydrogen binary system

Annette K. Kleppe, Mónica Amboage, Andrew P. Jephcoat

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The application of pressure to materials can reveal unexpected chemistry. Under compression, noble gases form stoichiometric van der Waals (vdW) compounds with closed-shell molecules such as hydrogen, leading to a variety of unusual structures. We have synthesised Kr(H 2) 4 for the first time in a diamond-anvil high-pressure cell at pressures a ‰ 5.3a €...GPa and characterised its structural and vibrational properties to above 50a €...GPa. The structure of Kr(H 2) 4, as solved by single-crystal synchrotron X-ray diffraction, is face-centred cubic (fcc) with krypton atoms forming isolated octahedra at fcc sites. Rotationally disordered H 2 molecules occupy four different, interstitial sites, consistent with the observation of four Raman active H 2 vibrons. The discovery of Kr(H 2) 4 expands the range of pressure-stabilised, hydrogen-rich vdW solids, and, in comparison with the two known rare-gas-H 2 compounds, Xe(H 2) 8 and Ar(H 2) 2, reveals an increasing change in hydrogen molecular packing with increasing rare gas atomic number.

Original languageEnglish
Article number4989
JournalScientific reports
Volume4
DOIs
Publication statusPublished - May 16 2014

ASJC Scopus subject areas

  • General

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