New High Pressure Phases of the Zn–N System

The high pressure phase diagram of the Zn–N system is enriched by structural searching methods. Nine energetically stable phases with the stoichiometries of ZnN₂, ZnN₃ and ZnN₄ and one metastable phase with the stoichiometry of ZnN₆ are proposed at different pressures. The survival pressure range of the stable high pressure phases is determined by the enthalpy difference analysis. The N–N single bond of the armchair N-chain in the ZnN₄ and ZnN₆ structures exhibits covalent sigma bonds characteristics with the N atom in a sp² hybridization state. All the predicted new structures are metallic phase. The charge transfer between the Zn and N atoms results in an ionic bond interaction. The exhibited high energy density properties of the proposed <i>P-1</i>-ZnN₄, <i>Ibam</i>-ZnN₄ and <i>P-1</i>-ZnN₆ phases allow them to be potential high energy density materials.