Pressure-stabilized high-energy-density material YN 10 .

Polynitrogen compounds have been intensively studied for potential applications as high energy density materials, especially in energy and military fields. Here, using the swarm intelligence algorithm in combination with first-principles calculations, we systematically explored the variable stoichiometries of yttrium-nitrogen compounds on the nitrogen-rich regime at high pressure, where a new stable phase of YN 10 adopting I 4/ m symmetry was discovered at the pressure of 35 GPa and showed metallic character from the analysis of electronic properties. In YN 10 , all the nitrogen atoms were sp 2 -hybridized in the form of N 5 ring. Furthermore, the gravimetric and volumetric energy densities were estimated to be 3.05 kJ g -1 and 9.27 kJ cm -1 respectively. Particularly, the calculated detonation velocity and pressure of YN 10 (12.0 km s -1 , 82.7 GPa) was higher than that of TNT (6.9 km s -1 , 19.0 GPa) and HMX (9.1 km s -1 , 39.3 GPa), making it a potential candidate as a high-energy-density material.