Capturing High-Energy Polymeric Nitrogen Structures Stabilized by Lutetium at Ambient Conditions.

Polynitrogen with high energy and environmental friendliness has exhibited potential application in military and civilian fields. In this study, first-principle calculations were employed to conduct a comprehensive investigation of the nitrogen-rich Lu-N compounds. The research yielded ten novel polynitrides: 2/-LuN, 1̅-LuN, 1̅-LuN, 2/-LuN, 1̅-LuN, 1̅-LuN, 1̅-LuN, -LuN, 4/-LuN, and -LuN. It is noteworthy that two novel polymeric nitrogen structures have been observed in our prediction: an infinite tripodic-N chain formed in 2/-LuN, and a heart-shaped N ring band formed in -LuN. Excellent stabilities were observed in the calculated Lu-N compounds; 2/-LuN and 1̅-LuN are quenchable under ambient conditions. Meanwhile, the polynitrogen structures of 1̅-LuN and -LuN are calculated to decompose into thermally stable N rings and infinite N-chains under ambient conditions, respectively. -LuN is thermodynamically stable due to its high symmetry and efficient packing of the chain-like N cage. Moreover, the Lu-N compounds, which display favorable energy density (mass energy density () = 1.60-3.59 kJ/g; volumetric energy density () = 11.32-15.65 kJ/cm), are prospective candidates for environmentally friendly high-energy density materials. These results provide a good theoretical guide for the experimental synthesis of new energetic materials.