Predicted the structural diversity and electronic properties of Pt-N compounds under high pressure

The nitrogen-rich transition metal nitrides have attracted considerable attention due to their potential application as high energy density materials. Here, a systematic theoretical study of PtN (x) compounds has been performed by combining first-principles calculations and particle swarm-optimized structure search method at high pressure. The results indicate that several unconventional stoichiometries of PtN2, PtN4, PtN5, and Pt3N4 compounds are stabilized at moderate pressure of 50 GPa. Moreover, some of these structures are dynamically stable even when the pressure release to ambient pressure. The P (1) over bar PtN5 can release about 1.23 kJ g(-1) and 1.71 kJ g(-1), respectively, upon the decomposition into elemental Pt and N-2. The electronic structure analysis shows that all crystal structures are indirect band gap semiconductors, except for the metallic Pt3N4 with Pc phase, and the metallic Pt3N4 is a superconductor with estimated critical temperature T (c) values of 3.6 K at 50 GPa. These findings not only enrich the understanding of transition metal platinum nitrides, but also provide valuable insights for the experimental exploration of multifunctional polynitrogen compounds.