Predicted Pressure-Induced High-Energy-Density Iron Pentazolate Salts

Metal-pentazolate compounds as candidates for novel high-energy-density materials have attracted extensive attention in recent years. However, dehydrated pentazolate salts of transition metal iron are rarely reported. We predict two new iron pentazolate salts Fdd2-FeN_10 and P\bar1(No.1)-FeN_10 using a constrained crystal search method based on first-principles calculations. We propose that the stable Fdd2-FeN_10 crystal may be synthesized from FeN and N_2 above 20 GPa, and its formation enthalpy is lower than the reported iron pentazolate salt (marked as P\bar1(No.2)-FeN_10). Crystal P\bar1(No.1)-FeN_10 is composed of iron bispentazole molecules. Formation enthalpy, phonon spectrum and ab initio molecular dynamics calculations are performed to show their thermodynamic, mechanical and dynamic properties. Moreover, the high energy density (3.709 kJ/g, 6.349 kJ/g) and good explosive performance indicate their potential applications as high-energy-density materials.