Atomistic insights on enhanced passivity: DFT study of substitutional Mo on Cr2O3 and Fe2O3 surfaces

Xian Huang (1) , Dominique Costa (1) , Boubakar Diawara (1) , Vincent Maurice (1) , Philippe Marcus (1)

1 IRCP - Institut de Recherche de Chimie Paris

Substitution of a metal cation by Mo and its effects on vacancy formation on (0001)-oriented chromia and hematite surfaces were studied using DFT calculations to provide atomistic insights on the experimentally observed Mo-enhanced passivity. The substitution is favoured energetically, resulting in Mo more enriched in the Fe-rich than in the Cr-rich oxide zones in passive oxide films. The presence of substitutional Mo disfavours the formation of O vacancies and favours metal vacancies, more significantly in Fe2O3 than in Cr2O3, suggesting a prevention of passivity breakdown in chloride-rich environment and a cure of the Fe-rich weak sites of passivity by Mo.

Mots clés: stainless steel; DFT; passive films; Mo effects; vacancies

Domaines: Chimie inorganique; Chimie théorique et/ou physique

Xian Huang, Dominique Costa, Boubakar Diawara, Vincent Maurice, Philippe Marcus. Atomistic insights on enhanced passivity: DFT study of substitutional Mo on Cr2O3 and Fe2O3 surfaces. Corrosion Science, 2023, 224, pp.111543. ⟨10.1016/j.corsci.2023.111543⟩. ⟨hal-04224716⟩