Spontaneous formation of filled-shell CsI-Xenon solid solutions under high temperature and high pressure

Abstract

Different stoichiometries compounds formed by filled-shell (FS) insulators (e.g., xenon) have been extensively predicted and successfully synthesized under extreme conditions. However, theoretical prediction on solid solution formed by FS materials is lacking. Here, by combining structure searching and ab initiohybrid Metropolis-Monte Carlo/molecular dynamics simulations, we predict that the noble gas xenon and CsI can form thermodynamically stable substitutional solid solutions with hexagonal close-packed at high temperature and high pressure, in which Xe, Cs and I exhibit similar electronegativity and strong metallic feature that are analogous to the solid solution alloys. The existence of short-range order among constituent compositions improves the stability of solid solution. These results shed a new insight on the chemical reactivity between noble gases and alkali-halide compounds and provide valuable reference to understand the formation of multicomponent solid solutions under extreme conditions.