Superionic xenon–water compounds under high pressure

The reaction of water ice with other substances or compounds under high temperatures and pressures have important implications for the composition and evolution of planetary interiors. In recent years, the exploration for stable compounds of the noble gases xenon combined with water ice has been a concern in field of high-pressure science. To explore this question, using crystal structure predictions and first-principles calculations, we found stable xenon-water compounds at high pressure. Further molecular dynamics simulations show that the Xe-H2O compounds exhibit superionic states behavior at high temperature and pressure conditions, in which the xenon and oxygen atoms framework is fixed and hydrogen atoms diffuse freely like a liquid. The insertion of xenon atoms may alter the superionicity of pure water, reducing the pressure and temperature that superionic states is formed.