CUED Publications database

A stable compound of helium and sodium at high pressure

Dong, X and Oganov, AR and Goncharov, AF and Stavrou, E and Lobanov, S and Saleh, G and Qian, GR and Zhu, Q and Gatti, C and Deringer, VL and Dronskowski, R and Zhou, XF and Prakapenka, VB and Konôpková, Z and Popov, IA and Boldyrev, AI and Wang, HT (2017) A stable compound of helium and sodium at high pressure. Nature Chemistry, 9. pp. 440-445. ISSN 1755-4330

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Helium is generally understood to be chemically inert and this is due to its extremely stable closed-shell electronic configuration, zero electron affinity and an unsurpassed ionization potential. It is not known to form thermodynamically stable compounds, except a few inclusion compounds. Here, using the ab initio evolutionary algorithm USPEX and subsequent high-pressure synthesis in a diamond anvil cell, we report the discovery of a thermodynamically stable compound of helium and sodium, Na 2 He, which has a fluorite-Type structure and is stable at pressures >113â €..GPa. We show that the presence of He atoms causes strong electron localization and makes this material insulating. This phase is an electride, with electron pairs localized in interstices, forming eight-centre two-electron bonds within empty Na 8 cubes. We also predict the existence of Na 2 HeO with a similar structure at pressures above 15â €..GPa.

Item Type: Article
Divisions: Div C > Applied Mechanics
Div C > Materials Engineering
Depositing User: Cron Job
Date Deposited: 04 Jul 2018 20:10
Last Modified: 13 Apr 2021 08:56
DOI: 10.1038/nchem.2716