Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 31: Metal & Semiconductor substrates: Adsorption and reaction of small molecules – Poster
O 31.1: Poster
Montag, 9. März 2026, 18:00–20:00, P2
Investigating the native oxide layer of CoCrFeNi(100) by co-adsorption of O2 and H2: an XPS study — •Peter Richter, Kavya Harsha Kumar, Susanne Wolff, and Thomas Seyller — Technische Universität Chemnitz, Chemnitz, Deutschland
High-entropy alloys (HEAs) are a relatively new class of materials with potential applications under ambient conditions. Hence, understanding the formation and the properties of their native oxides is essential. In this study, we use X-ray photoelectron spectroscopy to investigate the native oxide layer present on CoCrFeNi(100) as well as on the clean surface subjected to controlled exposures of O2 and H2.
To evaluate the stability of the native oxide layer, samples were annealed in ultra-high vacuum at temperatures in the range of 350 to 1100 ∘C. Oxide reduction increased significantly at 700 ∘C and was complete at 1100 ∘C. The exposure of clean CoCrFeNi(100) surfaces to 1 to 1000 L of O2 leads to controlled oxidation, with Cr contributing most to oxide formation, followed by Co and Fe. The subsequent introduction of H2 at sample temperatures of up to 500 ∘C leads to systematic changes in the surface chemistry.
Experimentally, the information of the bonding configuration is best observed in the 2p core levels of Co, Cr, Fe and Ni. However, when using the Al Kα line, several Auger peaks overlap with the Co2p and Fe2p core levels. In addition, multiplet splitting and satellite features further complicate the evaluation of the XPS data. To improve this, we performed reference measurements and developed fitting models for the Auger lines using pure metal foils.
Keywords: High-Entropy alloy; CoCrFeNi; XPS; Magnetron sputtering; Epitaxie