Structural stability and electronic properties of LiNiN

The structural stability and electronic properties of layered nitridometallate LiNiN have been investigated by first-principles calculations based on the density functional theory. Experiments show that LiNiN has a hexagonal structure, with alternate LiN and Ni planes stacking perpendicular to the Ni–N chains. However, our calculation shows that LiNiN in the simple tetragonal structure ( D 4 h 9 ) is more stable than the hexagonal one ( D 3 h ) . The phase transition between the hexagonal and tetragonal structures was discussed by supposing a medial phase and by calculating the transition pressure and energy barriers between them. The results suggest that the pressure-induced phase transition from tetragonal LiNiN to hexagonal one should be triggered by a negative pressure. Furthermore, electronic structure calculations suggest that tetragonal LiNiN may be more conductive than that of hexagonal phase, and the electronic conductivity of tetragonal LiNiN is isotropic, other than the anisotropic one for hexagonal LiNiN.