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

Abstract

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.

Stability, Chemical Bonding, and Electron Lone Pair Localization in AsN at High Pressure by Density Functional Theory Calculations

“…Indeed, while in both systems the orientation of the electron LPs is apparently and consistently adopted to minimize the electrostatic repulsive energy due to LPs interactions, compared to cg-N, where an all-gauche conformation drives the minimization of the LP repulsive energy, a partial trans conformation seems to favor this process in AsN, opening new perspectives about the possible existence of other stable or metastable AsN structures with different gauche/trans conformation ratio. A similar occurrence has been reported, for example, in the high pressure single-bonded polymeric structures of N, where black phosphorus type N (bP-N) exhibits two-thirds of the dihedral angles in gauche conformation (67°) and one-third in trans conformation (180°), 69 leading to the loss of the all-gauche helicity characterizing cg-N. These findings are extremely relevant, not only to the fundamental chemistry of pnictogens, but also to materials science for designing new advanced materials with ultralow thermal conductivity, because the presence of LPs has been indicated as a highly desirable key feature to achieve thermoelectric performance.…”

Primitive to conventional geometry projection for efficient phonon transport calculations

“…Figure 4 shows the thermal conductivities of bulk N2, GeTe, and CrCl3 as a function of temperature from 30 to 400 K. The crystalline N2 system considered here (a non-molecular solid that exists under high pressure 34,35 ) has isotropic thermal transport, i.e., 𝜅 𝑥𝑥 = 𝜅 𝑦𝑦 = 𝜅 𝑧𝑧 (offdiagonal terms are zero for all systems considered here), and has the highest 𝜅 of the three systems considered, with room temperature 𝜅 = 112.39 W/m-K. The large calculated 𝜅 values for N2 are expected given its strong covalent bonding and light atomic masses, with density and mass similar to those of diamond, the prototypical ultrahigh thermal conductivity material 51 .…”

“…We demonstrate the convenience of this PTS method by calculating phonon transport properties based on DFT for three materials from different space groups: GeTe with space group R3m, solid N2 with space group I213, and ferromagnetic CrCl3 with space group R-3. These are representative materials with different levels of complexity in conventional cells and have important applications in thermoelectrics (GeTe) [30][31][32][33] , energy storage (N2) 34,35 , and two-dimensional magnetism (CrCl3) [36][37][38][39][40] .…”

N-Methylene-C bridged tetrazole and 1,2,4-triazole energetic salts as promising primary explosives

“…11 In recent studies, nitrogen-rich energetic heterocycles have garnered considerable attention from researchers owing to their notable characteristics, including a high heat of formation, exceptional detonation performance, robust thermal stability, and eco-friendliness. [12][13][14][15] Among these nitrogen-rich compounds, triazole and tetrazole have emerged as particularly promising candidates, exhibiting commendable detonation properties when combined with energetic groups such as nitro and nitramino moieties. Consequently, they are frequently employed in the synthesis of novel energetic materials.…”