Abstract:
Based on density functional theory and the crystal structure prediction methods, USPEX and AIRSS, stable intermediate compounds in the Ni-X (X = B, C, and N) systems and their structures were determined in the pressure range of 0-400 GPa. It was found that in the Ni-B system, in addition to the known ambient-pressure phases, the new nickel boride, Ni2B3-Immm, stabilizes above 202 GPa. In the Ni-C system, Ni3C-Pnma was shown to be the only stable nickel carbide which stabilizes above 53 GPa. In the Ni-N system, four new phases, Ni6N-R3, Ni3N-Cmcm, Ni7N3-Pbca, and NiN2-Pa3, were predicted. For the new predicted phases enriched by a light-element, Ni2B3-Immm and NiN2-Pa3, mechanical and electronic properties have been studied.
