Mechanism of Co atom point defects on different termination surfaces of WC–Co/diamond interface by first-principles

Based on the density functional theory, the first-principles method had been used to calculate the binding energy, the charge density of the interface, Mulliken population, density of states, band structure and phonon dispersion analysis of Co atom point defects on the W-terminated surface and C-terminated surface of the WC–Co/Diamond film-base interface. The results showed that the binding energy of W-GD, W-VD, W-SD sites on the W termination surface with WC–Co/Diamond interface was gradually weakened. And the binding energy of C-GD, C-SD, C-VD sites on the C termination surface was the same as the former. From the charge density, Co atom on the W-terminated surface of WC(100) had a stronger influence on the film-base interface than the C-terminated surface. From the analysis of the Mulliken population, the ability of Co to transfer charge on W-terminated surface was stronger than C-terminated surface. According to the density of states analysis, the Fermi level state density of the W terminal surface was higher than that of the C terminal surface and the activity of the W terminal surface was higher than that of the C terminal surface. Through the analysis of the electronic energy band structure, the system indicated significant metallicity. The phonon spectrum showed that the presence of Co atoms on the W-terminated surface and C-terminated surface of the WC–Co/Diamond film-base interface is stable.