Stable Xenon Nitride at High Pressures

TL;DR

This paper demonstrates that high pressure enables the formation of a novel xenon nitride compound, XeN6, with high energy density and unique chemical structure, opening new possibilities for noble gas chemistry.

Contribution

It reveals that high pressure can induce reactivity between inert N2 and Xe, leading to the discovery of a stable XeN6 nitride with unprecedented bonding and high energy density.

Findings

XeN6 has a high-energy-density of ~2.4 kJ/g.

XeN6 features chair-shaped N6 hexagons and 12 Xe-N bonds.

High pressure facilitates the formation of noble gas nitrides.

Abstract

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.