Composition and electrical conductivity of some cobaltates of the type La2−xSrxCoO4.5−x/2±δ

Vashook, V.; Ullmann, H.; Ol'shevskaya, O. P.; Kulik, V.P; Lukashevich, V. E.; Kokhanovskij, L.V

doi:10.1016/s0167-2738(00)00774-8

Cited by 48 publications

(41 citation statements)

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“…Furthermore, it is not clear how the increased amount of oxygen vacancies in LSC 214 is to enhance the ORR activity by several orders of magnitude since the interstitial path into LSC 214 and similar RP phase compounds is already very fast. Therefore, in this study, we focus on the interstitial oxygen incorporation and transport as the dominant ORR path on LSC 214 with a Sr doping level ≤ 50%, 36,37 rather than a vacancy dominated oxygen incorporation process. In this paper, we quantitatively probe the two above-discussed mechanisms for the reported enhancement of the ORR activity at the hetero-interface of LSC 113 /LSC 214 .…”

Section: Introductionmentioning

confidence: 99%

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

Han

Yildiz

2012

Energy Environ. Sci.

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: Introductionmentioning

confidence: 99%

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

Han

Yildiz

2012

Energy Environ. Sci.

118

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“…Additionally, K 2 NiF 4 -type phases such as La 2 NiO į have recently attracted considerable interest as alternative materials for solid oxide fuel cells due to their interesting transport properties [1,2]. As n=1 members of the Ruddlesden-Popper phases, the K 2 NiF 4 -type oxides have shown an enhanced stability under reducing conditions due to their ability to accommodate a wide range of coordination environments and oxidation states.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of La0.8Sr1.2Co0.5M0.5O4−δ (M=Fe, Mn)

El‐Shinawi

Marco

Berry

et al. 2009

Journal of Solid State Chemistry

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“…It might be due to thermally activated Co ions. In the high temperature region, Co 3+ ions in B site could transform into Co 2+ and Co 4+ ions [15]. The changed Co 2+ and Co 4+ ions create Co 0…”

Section: Resultsmentioning

confidence: 99%

Characterization of NdSrCo1−xFexO4+δ (0≤x≤1.0) intergrowth oxide cathode materials for intermediate temperature solid oxide fuel cells

Song

Lee

2011

Ceramics International

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Composition and electrical conductivity of some cobaltates of the type La2−xSrxCoO4.5−x/2±δ

Cited by 48 publications

References 11 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

Synthesis and characterization of La0.8Sr1.2Co0.5M0.5O4−δ (M=Fe, Mn)

Characterization of NdSrCo1−xFexO4+δ (0≤x≤1.0) intergrowth oxide cathode materials for intermediate temperature solid oxide fuel cells

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