Simulation of ion transport in layered cuprates La2 − x Sr x CuO4 − δ

Саввин, С.Н.; Мазо, Г. Н.; Ivanov-Schitz, A. K.

doi:10.1134/s1063774508020193

Cited by 18 publications

(21 citation statements)

References 28 publications

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“…6,12,13,[17][18][19][20][21][22][23] In support of our second hypothesis, lattice strain was recently shown to alter the oxygen defect chemistry as well as the oxygen reaction and diffusion kinetics on perovskite oxides.…”

Section: Introductionsupporting

confidence: 57%

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Han

Yildiz

2012

Energy Environ. Sci.

119

118

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The recently reported fast oxygen reduction kinetics at the interface of (La,Sr)CoO 3-δ (LSC 113 ) and (La,Sr) 2 CoO 4+δ (LSC 214 ) phases opened up new questions for the potential role of dissimilar interfaces in advanced cathodes for solid oxide fuel cells (SOFCs). Using first-principles based calculations in the framework of density functional theory, we quantitatively probed the possible mechanisms that govern the oxygen reduction activity enhancement at this hetero-interface as a model system. Our findings show that both the strongly anisotropic oxygen incorporation kinetics on the LSC 214 and the lattice strain in the vicinity of the interface are important contributors to such enhancement. The LSC 214 (100) surface exposed to the ambient at the LSC 113 /LSC 214 interface facilitates oxygen incorporation because the oxygen molecules very favorably adsorb on it compared to the LSC 214 (001) and LSC 113 (001) surfaces, providing a large source term for oxygen incorporation. Lattice strain field present near the hetero-interface accelerates oxygen incorporation kinetics especially on LSC 113 (001). At 500 °C 4×10 2 times faster oxygen incorporation kinetics is predicted in the vicinity of the LSC 113 /LSC 214 heterointerface with 50% Sr-doped LSC 214 compared to that on the single phase LSC 113 (001) surface.Contributions from both the anisotropy and local strain effects are of comparable magnitude. The insights obtained in this work suggest that hetero-structures which have a large area of (100) surfaces and smaller thickness in [001] direction of the Ruddlesden-Popper phases, and larger tensile strain near the interface would be promising for high-performance cathodes.Keywords: solid oxide fuel cell, oxygen reduction reaction, cathode, anisotropy, strain, perovskite, Ruddlesden-Popper, (La,Sr)CoO 3 , (La,Sr) 2 CoO 4+δ , density functional theory * Corresponding author. Email: byildiz@mit.edu 2 Graphical AbstractAnisotropic oxygen incorporation on (La,Sr) 2 CoO 4+δ and the lattice strain near the (La,Sr)CoO 3-δ / (La,Sr) 2 CoO 4+δ interface serve as two possible sources to accelerate the oxygen reduction kinetics on the hetero-structure by 4×10 2 times at 500 °C. Broader contextHigh efficiency and fuel flexibility of Solid Oxide Fuel Cells (SOFCs) render them attractive as a sustainable energy conversion technology. There is growing interest in the design of dissimilar interfaces at the nano-scale to enable high-performance SOFC cathodes with fast oxygen reduction reaction (ORR) kinetics at lower temperatures than their traditional operation temperature of 800 °C. A motivating example for this purpose has been the hetero-structure made of the (La,Sr)CoO 3-δ and (La,Sr) 2 CoO 4+δ phases with highly active interfaces. Two previous experimental reports have observed 10 3 -10 4 times enhancement in ORR kinetics at 500-550 °C arising from the interface of these two phases. However, these empirical observationshave not yet reached a fundamental understanding of why these interfaces are so highly active...

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Section: Introductionsupporting

confidence: 57%

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Han

Yildiz

2012

Energy Environ. Sci.

119

118

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“…MD simulations by Mazo et al [73] of LSCuO 214 (Sr = 0.37) demonstrated that a strong anisotropy of the crystal structure can lead to different oxygen transport properties in (La,Sr)O blocks and CuO 2 layers, the latter being more favorable for oxygen transport via a conventional vacancy migration mechanism. More recently, Savvin et al [74] also investigated the oxygen diffusion processes in LSCuO 214 (Sr = 0.15 and 1.0) via MD simulations, demonstrating that oxygen migration occurs mainly in CuO 2 layers as a result of a hopping mechanism. The authors proposed that, by jumping to the nearest position or along the CuO 2 layers, oxygen can migrate in LSCuO 214 .…”

Section: Oxygen Migration Mechanisms In Ruddlesden–popper Oxidesmentioning

confidence: 99%

Controlling Oxygen Mobility in Ruddlesden–Popper Oxides

Lee

2017

Materials

123

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Discovering new energy materials is a key step toward satisfying the needs for next-generation energy conversion and storage devices. Among the various types of oxides, Ruddlesden–Popper (RP) oxides (A2BO4) are promising candidates for electrochemical energy devices, such as solid oxide fuel cells, owing to their attractive physicochemical properties, including the anisotropic nature of oxygen migration and controllable stoichiometry from oxygen excess to oxygen deficiency. Thus, understanding and controlling the kinetics of oxygen transport are essential for designing optimized materials to use in electrochemical energy devices. In this review, we first discuss the basic mechanisms of oxygen migration in RP oxides depending on oxygen nonstoichiometry. We then focus on the effect of changes in the defect concentration, crystallographic orientation, and strain on the oxygen migration in RP oxides. We also briefly review their thermal and chemical stability. Finally, we conclude with a perspective on potential research directions for future investigation to facilitate controlling oxygen ion migration in RP oxides.

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“…In particular, over the past 15 years, researchers have demonstrated that the doped lanthanum Ni-, Co-, Cu-, and Fe-based Ruddlesden-Popper materials all show either fast oxygen surface exchange, efficient bulk oxygen transport, or both. 2,[8][9][10][11][12][13][14][15][16][17][18][19] A special aspect of Ruddlesden-Popper oxides that sets them apart from perovskites and most other oxygen conductors is that, whereas perovskites and other oxygen conductors tend to either be stoichiometric or contain oxygen vacancies, Ruddlesden-Popper materials may be stoichiometric, or contain some mixture of vacancies and/or interstitials. Based on the material composition and operating environment (temperature and oxygen partial pressure), Ruddlesden-Popper oxides may therefore range from hypostoichiometric (more oxygen vacancies than interstitials) to hyperstoichiometric (more interstitials than vacancies).…”

Section: Introductionmentioning

confidence: 99%

Factors Controlling Oxygen Interstitial Diffusion in the Ruddlesden–Popper Oxide La_2–xSr_xNiO_4+δ

Jacobs

Morgan

2018

Chem. Mater.

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The development of Ruddlesden-Popper oxides as oxygen exchange and transport materials for applications such as solid oxide fuel cells, oxygen separation membranes, and chemical looping will benefit from detailed mechanistic understanding of how oxygen is transported through these materials. Using Density Functional Theory, we found there are two distinct oxygen interstitial diffusion mechanisms involving two different oxygen interstitial species that can be active in La 2-x Sr x NiO 4+δ , and, we believe, in hyperstoichiometric Ruddlesden-Popper oxides in general. The first mechanism is the previously proposed interstitialcy-mediated mechanism, which consists of diffusing oxide interstitials. The second mechanism is newly discovered in this work, and consists of both oxide and peroxide interstitial diffusing species. This mechanism exhibits a similar or possibly lower migration barrier than the interstitialcy mechanism for high oxidation states. Which mechanism contributes to the oxygen interstitial diffusion is the result of the change in relative stability between the oxide interstitial (2-charge) and peroxide interstitial (1-charge), which directly affects the migration barriers for these two different mechanisms. The stability of the oxide and peroxide, and therefore the competition between the two oxygen diffusion mechanisms, is highly sensitive to the overall oxidation state of the system. Therefore, the oxygen diffusion mechanism is a function of the material composition, oxygen off-stoichiometry, operating temperature and oxygen partial pressure. We also examined the effect of epitaxial strain on both oxygen diffusion mechanisms, and found that tensile and compressive epitaxial strain of up to 2% had less than 100 meV/(% strain) effects on oxygen interstitial formation, migration, and activation energies, and that total achievable activation energy reductions are likely less than 100 meV for up to ±2% epitaxial strain. The presented understanding of factors Supporting Information

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Simulation of ion transport in layered cuprates La2 − x Sr x CuO4 − δ

Cited by 18 publications

References 28 publications

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Controlling Oxygen Mobility in Ruddlesden–Popper Oxides

Factors Controlling Oxygen Interstitial Diffusion in the Ruddlesden–Popper Oxide La_2–xSr_xNiO_4+δ

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Simulation of ion transport in layered cuprates La2 − x Sr x CuO4 − δ

Cited by 18 publications

References 28 publications

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Controlling Oxygen Mobility in Ruddlesden–Popper Oxides

Factors Controlling Oxygen Interstitial Diffusion in the Ruddlesden–Popper Oxide La2–xSrxNiO4+δ

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Factors Controlling Oxygen Interstitial Diffusion in the Ruddlesden–Popper Oxide La_2–xSr_xNiO_4+δ