Prediction of Gadolinium Polynitrides at High Pressures as High-Energy-Density Materials

Pressure-induced nitrogen-rich compounds hold significant application prospects in high-energy-density materials. Utilizing first-principles calculations and swarm-intelligence structure search methods, we have identified ten new types of Gd-N compounds with different configurations, such as one-dimensional N-chains composed of N6 rings or N8 rings, and two-dimensional N-layers constructed of N14 rings, N18 rings, or N18 + N6 rings. Moreover, the predicted Gd-N compounds exhibit different magnetic properties, and a magnetic phase diagram is constructed in the pressure range of 0 to 200 GPa. Remarkably, the volumetric energy density (11.58–17.79 kJ/cm3) of Gd polynitrides with high nitrogen content, including P-1(I)-GdN6, P-1(II)-GdN6, R-3-GdN8, C2mm-GdN9, and P1-GdN10, surpassed that of TNT (7.05 kJ/cm3), making them promising candidates for energetic materials. The discovery of diverse chain-like and layered structures in the GdNx compounds highlights the role of gadolinium in inducing the diversity and complexity of nitrogen arrangements.