Stable Xenon Nitride at High Pressures

Nitrides in many ways are fascinating since they often appear as superconductors, high energy density and hard materials. Though there exist a large variety of nitrides, noble gas nitrides are long missing in nature. Pursuit of noble gas nitrides has therefore become the subject of topical interests, but remains as a great challenge since molecular nitrogen (N2, a major form of nitrogen) and noble gases are both inert systems and do not interact at normal conditions. We show through a swarm structure searching simulation that high pressure can lift the reactivity of both N2 and xenon (Xe), making chemical reaction of them possible. The resultant nitride has a peculiar stoichiometry of XeN6, possessing a high-energy-density of approximately 2.4 kJg-1, rivaling that of the modern explosives. Chemically, XeN6 is more intriguing with the appearance of chaired N6 hexagons and an emergent 12-fold Xe by acceptance of unprecedentedly 12 Xe-N weak covalent bonds. Our work opens up the possibility of achieving Xe nitrides whose formation is long sought as impossible.