Study of the surface segregation of carbon vacancies in

Density functional theory (DFT) calculations have been performed to study the surface segregation of carbon vacancies in TiCx in this work. The results confirm that the vacancies in the surface have the smaller formation energy and less effect on the electronic structure of TiCx than those in the bulk, which indicates that the carbon vacancies in TiCx prefer to segregate on the surface. It is also found that energy barriers for the migration of the vacancies are dependent on their locations, and the deeper the location of vacancies is in the bulk, the higher is the diffusion energy barrier needed.