Abstract
The adsorption of oxygen on bcc Fe–Cr(100) surfaces with two different alloy concentrations is studied using ab initio density functional calculations. Atomic-scale analysis of oxygen–surface interactions is indispensable for obtaining a comprehensive understanding of macroscopic surface oxidation processes. Up to two chromium atoms are inserted into the first two surface layers. Atomic geometries, energies and electronic properties are investigated. A hollow site is found to be the preferred adsorption site over bridge and on-top sites. Chromium atoms in the surface and subsurface layers are found to significantly affect the adsorption properties of neighbouring iron atoms. Seventy-one different adsorption geometries are studied, and the corresponding adsorption energies are calculated. Estimates for the main diffusion barriers from the hollow adsorption site are given. Whether the change in the oxygen affinity of iron atoms can be related to the chromium-induced charge transfer between the surface atoms is discussed. The possibility to utilize the presented theoretical results in related experimental research and in developing semiclassical potentials for simulating the oxidation of Fe–Cr alloys is addressed.
Highlights
Iron–chromium alloys form the basis for the wide variety of transition metal alloys known as stainless steels
Yuan et al.[14] performed calculations based on the density functional theory (DFT) with the generalized-gradient approximation (GGA) to investigate the effect of segregating alloying elements on the oxygen adsorption on Fe(100) surfaces
Initial oxidation of Fe–Cr has been studied by medium-energy ion scattering (MEIS), Mössbauer and X-ray photoelectron spectroscopy (XPS)[2,22,23]
Summary
Iron–chromium alloys form the basis for the wide variety of transition metal alloys known as stainless steels. Already in 1976 Leygraf and H ultquist[10] investigated the initial oxidation of (110) and (100) surfaces in Fe and Fe–Cr using Auger electron spectroscopy (AES) and low-energy electron diffraction (LEED). They found that different oxides form on the (100) and (110) surfaces. Zimmermann and C iacchi[25] have investigated initial oxidation and oxide formation for the Cr(110) surface using molecular dynamics simulations and static structural DFT calculations They found that oxygen forms a perfect ad-layer before the actual formation of Cr oxides on the surface. Peruchetti et al.[27], Shinn and Madey[28] and Baca et al.[29] have investigated chemisorption of oxygen on Cr(100) and Cr(110) surfaces
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