Stability, Elastic Properties, and Deformation of LiBN₂: A Potential High-Energy Material

Searching for high-energy-density materials is of great interest in scientific research and for industrial applications. Using an unbiased structure prediction method and first-principles calculations, we investigated the phase stability of LiBN₂ from 0 to100 GPa. Two new structures with space groups P4̅2₁ m and Pnma were discovered. The theoretical calculations revealed that Pnma LiBN₂ is stable with respect to a mixture of ¹/₃Li₃N, BN, and ¹/₃N₂ above 22 GPa. The electronic band structure revealed that Pnma LiBN₂ has an indirect band gap of 2.3 eV, which shows a nonmetallic feature. The Pnma phase has a high calculated bulk modulus and shear modulus, indicating its incompressible nature. The microscopic mechanism of the structural deformation was demonstrated by ideal tensile shear strength calculations. It is worth mentioning that Pnma LiBN₂ is dynamically stable under ambient conditions. The decomposition of this phase is exothermic, releasing an energy of approximately 1.23 kJ/g at the PBE level. The results provide new thoughts for designing and synthesizing novel high-energy compounds in ternary systems.