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Article Dans Une Revue Solid State Ionics Année : 2019

Transport properties of Ce-doped nickel oxide and relevance on the thermal growth of oxide scales on CeO2-coated nickel

Résumé

The growth of oxide scales on Ce02-coated Ni polycrystals, in the temperature range 800–1200 °C, is analyzed taking into account both the transport properties of Ce-doped Ni1-xO single crystals, under non-equilibrium conditions, and a formal analysis of transport properties of cation deficient p-type semi conducting oxides in presence of an external driving force. It was shown that a key feature of the beneficial influence of Ce02-coatings on the layer growth is the kinetic demixing of cations, leading to an enrichment of cerium in the inner oxidation scale. It follows a higher cationic vacancy concentration near the metal/oxide interface, leading to a lower vacancy concentration gradient across the layer and a decrease of the driving force of diffusion controlling the oxidation kinetics. Further, the lower cation mobility in the outer layer due to the depletion of Ce4+, leads to a blocking effect of the outward diffusion of cations. It follows a local excess of Ni2+ and the formation of new oxide units which also contribute to a decrease of the oxidation rate.
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Dates et versions

hal-04472412 , version 1 (22-02-2024)

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N. Mahiouz, Z. Halem, N. Halem, G. Petot-Ervas. Transport properties of Ce-doped nickel oxide and relevance on the thermal growth of oxide scales on CeO2-coated nickel. Solid State Ionics, 2019, 339, pp.114943. ⟨10.1016/j.ssi.2019.04.006⟩. ⟨hal-04472412⟩
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