Prediction of pressure-induced stabilization of noble-gas-atom compounds with alkali oxides and alkali sulfides

摘要

The cubic antifluorite structure comprises a face-centered cubic sublatticeof anions with cations on the tetrahedral sites. The voids in the antifluoritestructure that are crucial for superionicity in Li2O might also act as atomictraps. Trapping of guest atoms and small molecules within voids of a hoststructure leads to the formation of what are known as clathrate compounds. Herewe investigate the possibility of trapping helium or larger neon guest atomsunder pressure within alkali metal oxide and sulfide structures and find stablehelium and neon bearing compounds even at pressures below 1 GPa. Thesestructures are stabilized by a reduction in volume from incorporation of heliumor neon atoms within the antifluorite structure. Our study suggests a novelclass of alkali oxide and sulfide materials incorporating noble gas atoms thatmight potentially be useful for gas storage.