New MgO-H_(2)O compounds at extreme conditions

The reaction of water and other materials has been the central topic under high-pressure physics research,because the Earth,super-Earth,Uranus,Neptune and other planets contain a great amount of water inside.However,the reaction between star-rich MgO and water under ultra-high pressure remains still poorly understood.Here,using ab initio evolutionary structure prediction researches of the structures of MgO-H_(2)O system at 300 GPa-600 GPa,we find that(MgO)2H_(2)O and MgO(H_(2)O)2 could become stable.The(MgO)2H_(2)O compounds may be an important component of super-Earth and the ice-rock boundary of Uranus and Neptune.Furthermore,it may be the reservoir under high pressure before the forming of the Earth’s core or other super-Earths.The current findings could expand our knowledge and improve our understanding of the evolution and composition of planets.