Pressure-induced nitrogen-rich GeN20 with pentazolate units

Area of Science:

• Materials Science
• Computational Chemistry
• Inorganic Chemistry

Background:

• Polynitride compounds are of significant interest due to their unique nitrogen structures and high energy densities.
• Metal-bearing nitrogen-rich compounds, particularly those containing the pentazolate anion (cyclo-N5-), are highly sought after for research and applications.

Purpose of the Study:

• To explore the germanium-nitrogen system under high pressure using computational methods.
• To design and identify novel, stable, high-energy density materials based on nitrogen-rich compounds.

Main Methods:

• Comprehensive first-principles structure search simulations were employed to investigate the germanium-nitrogen system at high pressure (49 GPa).
• The stability of the predicted material was assessed through dynamic, mechanical, and thermal stability analyses.

Main Results:

• A previously unknown unconventional stoichiometric material, GeN20, was identified, predicted to be stable at 49 GPa.
• The compound Ge(N5)4, featuring the cyclo-N5- anion, was discovered, stabilized by strong covalent N-N bonds and charge transfer from Ge to N.
• Ge(N5)4 exhibits high energy density (4.1 kJ g-1), high detonation pressure (619 kbar), and high explosion velocity (11.42 km s-1), surpassing TNT, with environmentally friendly detonation products. It also possesses an indirect bandgap of 3.0 eV, indicating potential optical properties.

Conclusions:

• The computational discovery of Ge(N5)4 demonstrates the feasibility of synthesizing novel, high-performance energetic materials through rational design.
• The predicted stability and superior energetic properties of Ge(N5)4 suggest its potential for future applications.
• These findings provide valuable insights for the design and synthesis of advanced nitrogen-based functional materials.