Effect of Niobium on the Defect Chemistry and Oxidation Kinetics of Tetragonal ZrO2
| Autor: | Mostafa Youssef, Uuganbayar Otgonbaatar, Bilge Yildiz, Wen Ma |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Metallurgy
Oxide Niobium chemistry.chemical_element Surfaces Coatings and Films Electronic Optical and Magnetic Materials Corrosion chemistry.chemical_compound Tetragonal crystal system General Energy chemistry X-ray photoelectron spectroscopy Oxidation state Physical chemistry Density functional theory Physical and Theoretical Chemistry Dissolution |
| Zdroj: | The Journal of Physical Chemistry C. 118:20122-20131 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/jp504874v |
| Popis: | Zirconium–niobium alloys are currently proposed for applications in water-cooled nuclear reactors. However, the mechanisms by which Nb impacts the corrosion resistance of these alloys are yet to be clarified. In this work, we utilize a thermodynamic framework informed by density functional theory calculations to predict the effect of Nb on the equilibria of charged defects in tetragonal ZrO2, and discuss how the changes in the defect concentrations affect the protectiveness of this oxide that grows natively on Zr alloys during oxidation. Our analysis shows that Nb dissolves predominantly in the oxidation state 5+ as a substitutional defect on the Zr sublattice, with charge compensation achieved by the negatively charged Zr vacancies. Moreover, Nb dissolution is limited to the oxygen-rich conditions, i.e., in the oxide surface facing oxidizing environment. We validate this finding by performing X-ray photoelectron spectroscopy on oxidized Zr–Nb alloys. The introduction of Nb in tetragonal ZrO2 is found to ... |
| Databáze: | OpenAIRE |
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