Plasma oxidation as a tool to design oxide films at low temperatures

Interfacial oxidation, an established approach to produce surface thin films for catalysts, corrosion, ware protective coatings and electronic structures is currently performed by thermal, anodic, and plasma methods. Fundamental physical-chemical models that can allow film design, particularly on alloys are lacking and plasma oxidation is the least studied of these methods. In this work, plasma oxidation of three CuZr alloys (CuZr2, CuZr, and Cu51Zr14) has been studied using x-ray photoelectron spectroscopy and depth profiling methods. The dependence of the resulting oxide film on alloy composition and sample temperature during plasma oxidation is investigated. In contrast to thermal and electrochemical oxidation which lead to the formation of a zirconium oxide film, plasma oxidation leads to the formation of a copper oxide or metallic copper overlayer depending on temperature and copper concentration in the bulk. It is shown that plasma oxidation can be used to design oxide films at room temperature, which require high temperatures using thermal oxidation and are not achievable by anodic oxidation.