Uranium Matrix Of Aluminum Thin Film Growth Behavior And Film-based Interface Reaction

In this paper, Al thin film growth behavior on U underlayers and interface reaction between U and Al were investigated by Auger Electron Spectroscopy (AES). Total energy pseudopotential calculations based on density functional theory (DFT) have been used to study the aluminum adsorption onto α-U (001) and UO₂ (001) surface, which explained and inferred experiment results reasonably. Primary results include:1) At the alternative deposition mode, Al interacts with uranium, electrons transfer from aluminum atoms to uranium atoms, and interface diffusion action is not visible. While at the continuously deposition mode, interface reaction between U and Al is comparatively stronger. At room temperature, Al nanometer thin film growth on uranium followed the volmer-weber(VW) mode.2) During the process of aluminum deposition onto UO₂ surface alternatively at room temperature, Al interacts with UO₂, and electrons transfer from aluminum atoms to uranium atoms. Interface diffusion between UO₂ and Al is more evident than that between U and Al. Aluminum diffuses into interface region of UO₂ and U, and a coexistence region including Al, U and UO₂ is formed. At room temperature, Al thin film growth on UO₂ followed the VW mode. Under the influence of diffusion action, intensity curves which determine thin film growth mode have some alteration.3) At room temperature, uranium oxides and aluminum oxides form contemporarily in interface region at the same oxygen exposure. And diffusion between Al₂O₃ and UO₂ is visible. After annealing, interface reaction between U and Al increases, and a new Auger emission appears at 60eV of kinetic energy, which is presumed to be UA1_X. In addition, carbon-rich region form, and uranium carbide is formed, which keep Al from diffusion into U, and C from diffusion to U surface.4) Study of Al adsorption onto a-U (001) and UO₂ (001) surface by density functional theory shows: Al adsorption actions are chemically adsorption, Al reacts with U, which form intermetallics, and Al atom preferentially inhabits interspaces on the surface.All of these results give a good fundamental understanding of Al thin film growth mode on U metal, and interface reaction behavior between Al and U, which are the important references on engineering application research of U anti-corrosion design.