First-principles study of the microstructure evolution of the diamond (110) surface with the adsorption of Fe atoms

Understanding the diamond graphitization mechanism is an essential subject in manufacturing research since it helps elucidate the reason for the material removal. Our work addressed the mechanism of Fe-induced graphitization of diamond (1 1 0) surfaces (Dia-(1 1 0)-Surf) by first-principles calculations. The results pointed out that Fe atoms adsorbed at hollow sites could acquire the most stable configuration on the Dia-(1 1 0)-Surf. Meanwhile, the Fe adatom could change interlayer binding energies of CC bonds of various layered. As the amount of Fe atoms increased, the weakening/enhancement effect of CC bonds tended to be apparent. Interestingly, Fe adatoms not only changed interlayer binding energies of CC nearby but also affected the dissociation direction of the surface microstructure. The weakened CC bonds could provoke the flattening of the sixfold chair ring structure of C atoms. The extension direction of the sixfold chair ring structure changed from horizontal to oblique, resulting in eliminating lateral compressive stress. It might be the origin of the Fe-induced graphitization of Dia-(1 1 0)- Surf. Moreover, the migration behaviors of the Fe atom have been studied. It could be inferred that the migration activation energy and movement direction of Fe adatoms were associated with the material removal rate.