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 ˉ phase of PtN₄ and the P 1 ˉ phase of PtN₅ can release about 1.23 kJ g⁻¹ and 1.71 kJ g⁻¹, respectively, upon the decomposition into elemental Pt and N₂. 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.