Prediction of erbium-nitrogen compounds as high-performance high-energy-density materials

To explore high-energy-density materials, intense attention has been focused on how to stabilize the N-N bond in nitrogen-rich compounds. Here, we report several stable phases of erbium-nitrogen compounds ErNas high-energy-density materials. Specifically, the phase diagrams of stable high-pressure structuresImmm-ErN₂,C2-ErN₃,P1--ErN₄, andP1--ErN₆, are theoretically studied by combining first-principles calculation with particle swarm optimization algorithm. In these erbium-nitrogen compounds, the N-N bonds are stabilized as diatomic quasi-molecule N₂, helical-like nitrogen chains, armchair nitrogen chains, and armchair-anti-armchair nitrogen chains, respectively. Among them, theP1--ErN₆harbors excellent stability at high thermal up to 1000 K. More importantly, theP1--ErN₆has outstanding explosive performance with high-energy-density of 1.30 kJ g^-1, detonation velocity of 10.87 km s^-1, and detonation pressure of 812.98 kbar, which shows its promising application prospect as high-energy-density materials.