Effect of rare-earth doping on adsorption of carbon atom on ferrum surface and in ferrum subsurface: A first-principles study

Abstract

The adsorption of carbon atom on Fe surface and in Fe subsurface with and without rare earth (La and Ce) substitution in the surface layer and subsurface layer was studied by first-principles calculations. The carbon atom is predicted to adsorb at hollow and long bridge site on Fe(100) and Fe(110), respectively. However, the carbon atom shifts to occupy preferentially hollow site on both Fe(100) and Fe(110) with rare earth atom doping at surface layer. The lower adsorption energies involved with stronger adsorption abilities were obtained for carbon atoms on Fe surface with rare earth doping at surface layer, which was determined by the electronic structure of the surface atoms. The La atom was pulled out the surface after carbon adsorption due to strong interaction of La–C, which is consistent with the more charge transfer. In the subsurface region, the carbon atom prefers to occupy at octahedral site with rare earth doping at surface layer in Fe slab. These strong adsorption energies of the carbon atoms on Fe surface and in Fe subsurface with rare earth pose relevant insights into the interaction between carbon and rare earth, which helps to understanding the influence mechanism of rare earth in carburizing.