Energetic, mechanical, and vibrational stability of metastable OsC phase

摘要

The assessment of experimental and theoretical results shows controversy about the mechanical stability of OsC phases. The stability of WC-structured, NiAs-structured, and CoSn-structured OsC phases has been investigated by using first-principles calculations. Present results show that WC-OsC and NiAs-OsC are both unstable, energetically and vibrationally, at zero pressure. Further calculations show WC-OsC can be stabilized under high pressure but not NiAs-OsC, which is unstable even under very high pressure. It is found that the interaction between Os atoms in parallel x-y plane: is responsible for the deep instability of NiAs structure, while the greatly increased interaction under high pressure between nearest C-Os atoms is responsible for the stabilization of WC-OsC under high pressure.