Stability and diffusion properties of Ti atom on α-uranium surfaces: A first-principles study

Titanium (Ti) film is experimentally used to provide good protection for uranium (U) surface from corrosion, but the performance of the protector is limited by the strength of the Ti/U interface. Therefore, it is important to further understand the interaction between Ti atoms and U surfaces. Here the first-principles density functional theory approaches with spin polarization and non-spin polarization have been employed to study the stability and diffusion properties of Ti atoms on alpha-uranium (001) and (100) surfaces. The energetic, geometric parameters and electronic structures have been analyzed. For Ti/U(001) surface, it is found that the most energetically favoured configuration is Ti atom occupying the hollow2 site. Ti atom tends to diffuse from hollow1 site to hollow2 site via the longbridge site. The U-Ti bond is dominated by the hybridization between Ti 3d and U 5f states, and the negative charge is transferred to the first U layer from the adsorbed Ti atom. For Ti/U(100) surface, the hollow site is the most preferred site for the adsorption of Ti atom. Ti atom will overcome a low barrier of similar to 0.2 eV when it diffuses from one hollow site to another via the longbridge site. The topmost two U layers get electrons from Ti atom and the deeper U layers. (C) 2014 Elsevier B.V. All rights reserved.