Competing strain effects in reactivity of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>LaCoO</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>with oxygen

Kushima, Akihiro; Yip, Sidney; Yildiz, Bilge

doi:10.1103/physrevb.82.115435

Cited by 122 publications

(98 citation statements)

References 35 publications

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“…Both BM-SCO and P-SCO ozone films were subsequently annealed in-situ at 300 ºC in 500 Torr of O 2 for 5 minutes to explore the effects of strain in a highly oxidizing atmosphere known to convert unstrained SCO to the nearly stoichiometric perovskite. [23,25] As was reported elsewhere, [20,22] such annealing time and environment is known to fully oxidize samples. In either case, oxygen in BM-SCO or P-SCO ozone is respectively intercalated or deintercalated through the OVCs to approach a thermodynamically stable P-SCO state, where stoichiometry under even high oxygen partial pressure is dependent on strain (see Figure 1).…”

Section: Structural Analysis Of Annealed Bm-sco and P-sco Filmsmentioning

confidence: 88%

“…[13] This results in E a being composed of the difference between H saddle and H i . While H saddle only slightly lowers with tensile strain, H i significantly increases with tensile strain due to changes in the stabilizing effects of hybridization between Co 3d and O 2p, which are dependent on the Co-O bond length [20] .…”

Section: Strain Control Of Oxygen Activation Energy and Formation Entmentioning

confidence: 99%

“…While they predict that the activation energies of these vacancies can be tuned by tenths of an eV under modest strains of a few 3 percent, the initial energies of >2 eV render these changes relatively insignificant at reduced temperatures. [20][21][22] Therefore, to use strain as a new parameter for tuning the oxygen vacancy concentration, oxides with lower activation energies are in high demand.…”

Section: Introductionmentioning

confidence: 99%

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Strain Control of Oxygen Vacancies in Epitaxial Strontium Cobaltite Films

Petrie

Mitra

Jeen

et al. 2016

Adv Funct Materials

214

160

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The ability to manipulate oxygen anion defects rather than metal cations in complex oxides is facilitating new functionalities critical for emerging energy and device technologies.However, the difficulty in activating oxygen at reduced temperatures hinders the deliberate control of an important defect, oxygen vacancies. Here, strontium cobaltite (SrCoO x ) is used to demonstrate that epitaxial strain is a powerful tool for manipulating the oxygen vacancy concentration even under highly oxidizing environments and at annealing temperatures as low as 300 °C. By applying a small biaxial tensile strain (2%), the oxygen activation energy barrier decreases by ~30%, resulting in a tunable oxygen deficient steady-state under conditions that would normally fully oxidize unstrained cobaltite. These strain-induced changes in oxygen stoichiometry drive the cobaltite from a ferromagnetic metal towards an antiferromagnetic insulator. The ability to decouple the oxygen vacancy concentration from its typical dependence on the operational environment is useful for effectively designing oxides materials with a specific oxygen stoichiometry.2

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Section: Structural Analysis Of Annealed Bm-sco and P-sco Filmsmentioning

confidence: 88%

Section: Strain Control Of Oxygen Activation Energy and Formation Entmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Strain Control of Oxygen Vacancies in Epitaxial Strontium Cobaltite Films

Petrie

Mitra

Jeen

et al. 2016

Adv Funct Materials

214

160

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“…As shown in (by works including that of the authors here) to have a significant impact on facilitating oxygen ion transport, [24][25][26][27][28] vacancy formation, [29][30][31][32] and surface adsorption 27, 30 -specific to this paper's scope are the oxygen vacancy formation, oxygen adsorption and oxygen incorporation kinetics on the (La,Sr)CoO 3 films. 27,30,33 La 2 CoO 4+δ has not been a subject of similar studies to date, and we address the potential effects of strain also in this material as part of this paper.…”

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.

Self Cite

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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“…They found that the migration of oxygen vacancies and adsorbed oxygen were the key ratelimiting steps governing the overall oxygen incorporation kinetics. Planar tensile strain was predicted to reduce the oxygen vacancy formation energy and the oxygen vacancy migration barrier and strengthen oxygen adsorption on the LaCoO (001) surface [164,165]. These results suggest formation of a greater concentration of oxygen vacancies as active sites, an enhanced mobility of these sites on the surface, and a greater surface coverage of oxygen.…”

Section: Strain Segregation and Reactivitymentioning

confidence: 61%

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage

et al. 2014

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Functional materials for energy conversion and storage exhibit strong coupling between electrochemistry and mechanics. For example, ceramics developed as electrodes for both solid oxide fuel cells and batteries exhibit cyclic volumetric expansion upon reversible ion transport. Such chemomechanical coupling is typically far from thermodynamic equilibrium, and thus is challenging to quantify experimentally and computationally. In situ measurements and atomistic simulations are under rapid development to explore how this coupling can be used to potentially improve both device performance and durability. Here, we review the commonalities of coupling between electrochemical and mechanical states in fuel cell and battery materials, illustrating with specific cases the progress in materials processing, in situ characterization, and computational modeling and simulation. We also highlight outstanding questions and opportunities in these applications -both to better understand the limiting mechanisms within the materials and to significantly advance the durability and predictability of device performance required for renewable energy conversion and storage.

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Competing strain effects in reactivity ofLaCoO3with oxygen

Cited by 122 publications

References 35 publications

Strain Control of Oxygen Vacancies in Epitaxial Strontium Cobaltite Films

Strain Control of Oxygen Vacancies in Epitaxial Strontium Cobaltite Films

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

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage

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