关键词: pnictogen nitrides, structural stability, electronic property, energy density

Abstract: Recent experimental advancements reported a chemical reaction between antimony and nitrogen under high temperature and high pressure, yielding crystalline antimony nitride (Sb$_{3}$N$_{5}$) with an orthorhombic structure. Motivated by this statement, we calculate the stability, elastic properties, electronic properties and energy density of the $Cmc2_{1}$ structure for pnictogen nitrides $X_{3}$N$_{5}$ ($X=$ P, As, Sb, and Bi) using first-principles calculations combined with particle swarm optimization algorithms. Calculations of formation enthalpies, elastic constants and phonon spectra show that P$_{3}$N$_{5}$, As$_{3}$N$_{5}$ and Sb$_{3}$N$_{5}$ are thermodynamically, mechanically and kinetically stable at 35 GPa, whereas Bi$_{3}$N$_{5}$ is mechanically and kinetically stable but thermodynamically unstable. The computed electronic density of states shows strong covalent bonding between the N atoms and the phosphorus group atoms in the four compounds, confirmed by the calculated electronic localization function. We also calculate the energy densities for Sb$_{3}$N$_{5}$ and find it to be a potentially high-energy-density material.

Key words: pnictogen nitrides, structural stability, electronic property, energy density