Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3]
We present a multi-scale approach to predict equilibrium defect concentrations across oxide/oxide hetero-interfaces. There are three factors that need to be taken into account simultaneously for computing defect redistribution around the hetero-interfaces: the variation of local bonding environment...
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| Format: | Article |
| Language: | en_US |
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Royal Society of Chemistry
2017
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| Online Access: | http://hdl.handle.net/1721.1/107888 https://orcid.org/0000-0003-1855-0708 https://orcid.org/0000-0001-8966-4169 https://orcid.org/0000-0002-2688-5666 |
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| author | Yang, Jing Youssef, Mostafa Youssef Mahmoud Yildiz, Bilge |
| author2 | Massachusetts Institute of Technology. Department of Materials Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Materials Science and Engineering Yang, Jing Youssef, Mostafa Youssef Mahmoud Yildiz, Bilge |
| author_sort | Yang, Jing |
| collection | MIT |
| description | We present a multi-scale approach to predict equilibrium defect concentrations across oxide/oxide hetero-interfaces. There are three factors that need to be taken into account simultaneously for computing defect redistribution around the hetero-interfaces: the variation of local bonding environment at the interface as epitomized in defect segregation energies, the band offset at the interface, and the equilibration of the chemical potentials of species and electrons via ionic and electronic drift-diffusion fluxes. By including these three factors from the level of first principles calculation, we build a continuum model for defect redistribution by concurrent solution of Poisson's equation for the electrostatic potential and the steady-state equilibrium drift-diffusion equation for each defect. This model solves for and preserves the continuity of the electric displacement field throughout the interfacial core zone and the extended space charge zones. We implement this computational framework to a model hetero-interface between the monoclinic zirconium oxide, m-ZrO[subscript 2], and the chromium oxide Cr[subscript 2]O[subscript 3]. This interface forms upon the oxidation of zirconium alloys containing chromium secondary phase particles. The model explains the beneficial effect of the oxidized Cr particles on the corrosion and hydrogen resistance of Zr alloys. Under oxygen rich conditions, the ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] heterojunction depletes the oxygen vacancies and the sum of electrons and holes in the extended space charge zone in ZrO[subscript 2]. This reduces the transport of oxygen and electrons thorough ZrO[subscript 2] and slows down the metal oxidation rate. The enrichment of free electrons in the space charge zone is expected to decrease the hydrogen uptake through ZrO[subscript 2]. Moreover, our analysis provides a clear anatomy of the components of interfacial electric properties; a zero-Kelvin defect-free contribution and a finite temperature defect contribution. The thorough analytical and numerical treatment presented here quantifies the rich coupling between defect chemistry, thermodynamics and electrostatics which can be used to design and control oxide hetero-interfaces. |
| first_indexed | 2024-09-23T08:08:24Z |
| format | Article |
| id | mit-1721.1/107888 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T08:08:24Z |
| publishDate | 2017 |
| publisher | Royal Society of Chemistry |
| record_format | dspace |
| spelling | mit-1721.1/1078882022-09-30T07:49:56Z Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO2/Cr2O3 Yang, Jing Youssef, Mostafa Youssef Mahmoud Yildiz, Bilge Massachusetts Institute of Technology. Department of Materials Science and Engineering Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Yang, Jing Youssef, Mostafa Youssef Mahmoud Yildiz, Bilge We present a multi-scale approach to predict equilibrium defect concentrations across oxide/oxide hetero-interfaces. There are three factors that need to be taken into account simultaneously for computing defect redistribution around the hetero-interfaces: the variation of local bonding environment at the interface as epitomized in defect segregation energies, the band offset at the interface, and the equilibration of the chemical potentials of species and electrons via ionic and electronic drift-diffusion fluxes. By including these three factors from the level of first principles calculation, we build a continuum model for defect redistribution by concurrent solution of Poisson's equation for the electrostatic potential and the steady-state equilibrium drift-diffusion equation for each defect. This model solves for and preserves the continuity of the electric displacement field throughout the interfacial core zone and the extended space charge zones. We implement this computational framework to a model hetero-interface between the monoclinic zirconium oxide, m-ZrO[subscript 2], and the chromium oxide Cr[subscript 2]O[subscript 3]. This interface forms upon the oxidation of zirconium alloys containing chromium secondary phase particles. The model explains the beneficial effect of the oxidized Cr particles on the corrosion and hydrogen resistance of Zr alloys. Under oxygen rich conditions, the ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] heterojunction depletes the oxygen vacancies and the sum of electrons and holes in the extended space charge zone in ZrO[subscript 2]. This reduces the transport of oxygen and electrons thorough ZrO[subscript 2] and slows down the metal oxidation rate. The enrichment of free electrons in the space charge zone is expected to decrease the hydrogen uptake through ZrO[subscript 2]. Moreover, our analysis provides a clear anatomy of the components of interfacial electric properties; a zero-Kelvin defect-free contribution and a finite temperature defect contribution. The thorough analytical and numerical treatment presented here quantifies the rich coupling between defect chemistry, thermodynamics and electrostatics which can be used to design and control oxide hetero-interfaces. 2017-04-05T20:40:12Z 2017-04-05T20:40:12Z 2016-12 2016-07 Article http://purl.org/eprint/type/JournalArticle 1463-9076 1463-9084 http://hdl.handle.net/1721.1/107888 Yang, Jing, Mostafa Youssef, and Bilge Yildiz. “Predicting Point Defect Equilibria across Oxide Hetero-Interfaces: Model System of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3].” Phys. Chem. Chem. Phys. 19.5 (2017): 3869–3883. © Royal Society of Chemistry 2017 https://orcid.org/0000-0003-1855-0708 https://orcid.org/0000-0001-8966-4169 https://orcid.org/0000-0002-2688-5666 en_US http://dx.doi.org/10.1039/C6CP04997D Physical Chemistry Chemical Physics Creative Commons Attribution 3.0 Unported license http://creativecommons.org/licenses/by/3.0/ application/pdf Royal Society of Chemistry Royal Society of Chemistry |
| spellingShingle | Yang, Jing Youssef, Mostafa Youssef Mahmoud Yildiz, Bilge Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] |
| title | Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] |
| title_full | Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] |
| title_fullStr | Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] |
| title_full_unstemmed | Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] |
| title_short | Predicting point defect equilibria across oxide hetero-interfaces: model system of ZrO[subscript 2]/Cr[subscript 2]O[subscript 3] |
| title_sort | predicting point defect equilibria across oxide hetero interfaces model system of zro subscript 2 cr subscript 2 o subscript 3 |
| url | http://hdl.handle.net/1721.1/107888 https://orcid.org/0000-0003-1855-0708 https://orcid.org/0000-0001-8966-4169 https://orcid.org/0000-0002-2688-5666 |
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