Exploration of Si-N compounds as high energy density materials

Area of Science:

• Materials Science
• Chemistry
• Physics

Background:

• Non-molecular polymeric nitrogen phases are explored for high energy density materials (HEDMs).
• Silicon-based nitride materials offer a promising avenue for novel HEDM development.

Purpose of the Study:

• To investigate silicon-based nitride materials for potential HEDM applications.
• To predict and characterize new metastable phases of silicon nitride.

Main Methods:

• Utilized a structural search algorithm combined with first-principles calculations.
• Employed molecular dynamics simulations with machine-learned potentials.

Main Results:

• Predicted new metastable phases of SiN6, alongside stable Si3N4 and SiN2.
• Identified Cc-SiN6 as a polymeric nitrogen chain structure, quenchable at ambient pressure.
• Cc-SiN6 exhibits high volumetric energy density (12.81 kJ cm-3), detonation velocity (13.46 km s-1), and detonation pressure (110.42 GPa).
• Demonstrated stability up to 1500 K, with explosion triggered near 2000 K.

Conclusions:

• Cc-SiN6 is a promising high energy density material with superior volumetric energy density compared to TNT.
• The material's stability and detonation characteristics make it suitable for applications requiring compact warhead dimensions.
• Silicon-based nitrides represent a viable strategy for significantly enhancing HEDM performance.