Stabilized Nitrogen Framework Anions in the Ga-N System

Nitrogen-rich compounds have attracted significant fundamental and practical interest owing to their ability to accommodate diverse nitrogen-bonding patterns and their feasibility as high-energy-density materials. Herein, we examine a wide range of chemical compositions in the compressed Ga-N system using first-principles structural search and experimental preparation using a laser-heated diamond anvil cell. Our investigations have theoretically identified three thermodynamically stable stoichiometries─GaN₁₅, GaN₁₀, and GaN₅─with surprisingly versatile polymeric nitrogen framework topologies. Strikingly, our results show that the required synthetic pressures for forming polymeric nitrogen phases in GaN₁₀ and GaN₅ are much lower than that for pure solid nitrogen. Finally, we evaluated the energy involved in decomposing the compounds and validated that they are promising candidates for high-energy-density materials. These findings have broad implications for designing and synthesizing novel nitrogen-rich compounds through the reaction between p electron elements and nitrogen at modest pressures and for nitrogen chemistry under extreme conditions.