title: First-principles study on the incipient oxidization of Nb(110).
abstract: The incipient oxidization of Nb(110) has been investigated using the density functional theory method. We rationalize the well-known puzzle, i.e., Nb(110) is difficult to clean, by calculating the O dissolution, and the on-surface and subsurface adsorption at low concentration. It is found that the structure of on-surface O adsorption at 0.50 monolayer (ML) coverage has the largest binding energy and minimum work function, in agreement with experimental results. At 1.00 ML coverage, the inward diffusion of O atoms is promoted by O adatoms, attributed to the formation of a local electric field. Our theoretical results improve the understanding of the experiments showing that NbO(x) oxides on the surface can be formed and decomposed by treating samples at 1500-2000 K in vacuum. Furthermore, the thermodynamic analysis of the O/Nb(110) systems shows that bulk NbO is stable in vacuum, in agreement with the observed formation of NbO nanostructures on Nb(110).
authors.affiliation: School of Materials Science and Engineering, Beihang University, Beijing, People's Republic of China.
authors.forename: Qing-Gao
authors.initials: QG
authors.lastname: Wang
authors.forename: Jia-Xiang
authors.initials: JX
authors.lastname: Shang