Stability, Elastic Properties, and Deformation of LiBN: 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 LiBN from 0 to100 GPa. Two new structures with space groups P4̅2 m and Pnma were discovered. The theoretical calculations revealed that Pnma LiBN is stable with respect to a mixture of /LiN, BN, and /N above 22 GPa. The electronic band structure revealed that Pnma LiBN 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 LiBN 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.