Solid Nitrogen and Nitrogen-Rich Compounds as High-Energy-Density Materials

Polymeric allotropes of nitrogen and nitrogen-rich compounds containing N-N single bonds are attractive candidates for high-energy-density materials. However, the low kinetic stability of single bond in nitrogen means that these materials have to be synthesized under high pressure and temperature. Recent advances of experimental high-pressure techniques and computational structure prediction methods have enabled the investigation of many new nitrogen phases and nitrogen-rich compounds, and some have been successfully synthesized. Some of the recently synthesized materials have been retrieved at ambient conditions, and the large hysteresis warrants further application-inspired research. This review introduces the important classes of nitrogen-rich materials ranging from fundamental insight into bonding in nitrogen, to theoretical investigation of hypothetical compounds, and to laboratory realization of these energetic materials in diamond anvil cell. The progressive development of the field is narrated in chronological order, with the emphasis placed on recent progress in the last 2 years.