Exploration of Si-N compounds as high energy density materials.

The non-molecular phases of polymeric nitrogen formed under high pressure have potential applications in the area of high energy density materials (HEDMs). Herein, we explored silicon-based nitride materials using a structural search algorithm combined with first-principles calculations. We predicted new phases of SiN that are identified to be metastable together with the previously reported stable compositions of SiN and SiN. Among these, -SiN consists of a polymeric nitrogen chain, which is quenchable at ambient pressure, suggesting potential applications in HEDMs. Dissociation of SiN can lead to a remarkably high volumetric energy density of 12.81 kJ cm, which is ∼1.3 times larger than that of conventional TNT. Furthermore, an excellent performance in terms of detonation velocity (13.46 km s) and detonation pressure (110.42 GPa) highlights SiN as a promising HEDM. Molecular dynamics simulation using machine-learned potentials for 50 ps indicates that the structure is stable up to 1500 K and can trigger an explosion at nearly 2000 K temperature. The potential of -SiN is evident from its high detonation performance and volumetric energy density, making it ideal for scenarios where compact warhead dimensions are essential. This work highlights the possibility of utilizing silicon-based nitrides to significantly boost the performance of HEDMs.