The Stable or Metastable Phases in Compressed Zn-O Systems**Supported by the National Natural Science Foundation of China under Grant No 11347007, the Qing Lan Project, the Colleges and Universities in Jiangsu Province Natural Science Research Project under Grant No 14KJB460013, and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Abstract

Variable-composition evolutionary structure searches are used to explore stable stoichiometries for the Zn-O system below 300 GPa. Our results confirm the previous structural phase transition sequence of pressurised ZnO. ZnO is thermodynamically stable up to 300 GPa and zinc peroxide (ZnO2, space group Pa3̄) is metastable under lower pressure. Insulating I4/mcm-ZnO2 is thermodynamically stable between 128.3–300 GPa. Insulated metastable P3121-ZnO2, controlling the pressure range of 51.5–128.3 GPa, has a wide band gap compared to the Pa3̄-ZnO2 and I4/mcm-ZnO2. Phonon and elastic constant calculations conclude the dynamical and mechanical stability for the explored thermodynamically stable or metastable structures.