Ultra-incompressibility and high energy density of ReN 8 with infinite nitrogen chains

Nitrogen-rich transition metal nitrides are of great interests due to the unique physical and chemical properties. Here, we perform a detailed structural investigation of ReN 8 in the pressure range of 0–200 GPa via particle swarm optimization algorithm and first-principles calculations. Interestingly, four ReN 8 phases are firstly revealed to be stable within 200 GPa, N 2 dimers are found to be preferred in T -ReN 8 at pressure lower than 15.8 GPa and the infinite N ∞ chains become dominated in M -, T’ - and M’ -ReN 8 at higher pressure up to 200 GPa. We find that the Young’s moduli of M - and T’ -ReN 8 , about 850 GPa along [0.88 0 0.47] and [0 0 1] direction, are comparable to cubic BN, due to the presence of electronic accumulation in the N ∞ chains. Furthermore, M - and T’ -ReN 8 are found to be of high energy density of ~ 1.9 kJ/g (~ 11.0 kJ/cm 3 ). Graphical abstract Ultra-incompressibility of ReN 8 in special direction due to the high electronic accumulations in the polynitrogen chains.