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 sp(2) 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 P-1-ZnN4, Ibam-ZnN4 and P-1-ZnN6 phases allow them to be potential high energy density materials.