XPS Investigation\nof Co–Ni Oxidized Compounds\nSurface Using Peak-On-Satellite Ratio. Application to Co<sub>20</sub>Ni<sub>80</sub> Passive Layer Structure and Composition

XPS data processing for cobalt and nickel core-level\npeaks can\nbe complicated. This is especially true when analyzing a mixture of\noxide/oxyhydroxide/hydroxide compounds of these metals. The objective\nof this study is to develop a method for decomposing XPS spectra of\n2p core levels for nickel and cobalt-oxidized compounds. This methodology\nwas then employed to study the passivation layer of the Co<sub>20</sub>Ni<sub>80</sub> alloy. The analysis of Ni<sub>2p</sub> and Co<sub>2p</sub> photo peaks using a homemade code based on core-level peak\nstructure and satellites enables us to determine the chemical composition\nof the surface layer, knowledge of which is particularly important\nbecause it is directly linked to the anticorrosive properties it confers\non the surface of the oxidized alloy. The XPS analysis, coupled with\nsequential ion sputtering, revealed that the passive layer of the\nCo<sub>20</sub>Ni<sub>80</sub> alloy is heterogeneously covered with\neither oxidized cobalt compounds or oxidized nickel compounds. The\nmethod used also demonstrates that the chemical heterogeneity is associated\nwith the thickness heterogeneity of the passive layer.