Ordered Helium Trapping and Bonding in Compressed Arsenolite: Synthesis of As4O6·2He
Résumé
Compression of arsenolite has been studied from a joint experimental and theoretical point of view. Experiments on this molecular solid at high pressures with different pressure-transmitting media have been interpreted thanks to state-of-the-art ab initio calculations. Our results confirm arsenolite as one of the most compressible minerals and provide evidence for ordered helium trapping above 3 GPa between adamantane-type As4O6 cages. Our calculations indicate that, at relatively small pressures, helium establishes rather localized structural bonds with arsenic forming a new compound with stoichiometry As4O6·2He. All properties of As4O6·2He are different to those of parent As4O6. In particular, pressure-induced amorphization, which occurs in arsenolite above 15 GPa, is impeded in As4O6·2He; thus resulting in a mechanical stability of As4O6·2He beyond 30 GPa. Our work paves the way to explore the formation of new compounds by pressure-induced trapping and reaction of gases, small atomic or molecular species in the voids of molecular solids containing active lone electron pairs.
Domaines
Physique [physics]| Origine | Fichiers produits par l'(les) auteur(s) |
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