The New High-Pressure Phases of Nitrogen-Rich Ag-N Compounds.

The high-pressure phase diagram of Ag-N compounds is enriched by proposing three stable high-pressure phases (P4/mmm-AgN 2 , P1-AgN 7 and P-1-AgN 7 ) and two metastable high-pressure phases (P-1-AgN 4 and P-1-AgN 8 ). The novel N 7 rings and N 20 rings are firstly found in the folded layer structure of P-1-AgN 7 . The electronic structure properties of predicted five structures are studied by the calculations of the band structure and DOS. The analyses of ELF and Bader charge show that the strong N-N covalent bond interaction and the weak Ag-N ionic bond interaction constitute the stable mechanism of Ag-N compounds. The charge transfer between the Ag and N atoms plays an important role for the structural stability. Moreover, the P-1-AgN 7 and P-1-AgN 8 with the high-energy density and excellent detonation properties are potential candidates for new high-energy density species.