Anisotropic oxygen diffusion in tetragonal La<sub>2</sub>NiO<sub>4+δ</sub>: molecular dynamics calculations

Chroneos, Alexander; Parfitt, David; Kilner, John A.; Grimes, Robin W.

doi:10.1039/b917118e

Cited by 208 publications

(228 citation statements)

References 52 publications

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“…5 these NVT-predicted diffusivities (white triangles) are at the same order of magnitude and slightly underestimate the experimental results of Munnings et al 25 (black triangles in Fig. 5) and the previous MD 17 and experimental 20 results for La 2 NiO 4+d . Interestingly, in this second approach the activation energy for oxygen diffusion is calculated to be 0.23 eV and is effectively equivalent to the experimental value (0.12 eV, ref.…”

Section: Temperature Dependent Collective Oxygen Diffusionmentioning

confidence: 46%

“…We have previously shown that the MD calculations are in excellent agreement with experiments in the case of La 2 NiO 4+d . 17,20 In Fig. 5 we compare the MD predictions of diffusivity to the experimental results for La 2 CoO 4+d and La 2 NiO 4+d .…”

Section: Comparison With Experiments and Related Materialsmentioning

confidence: 99%

“…6,10 For La 2 NiO 4 , previous experimental studies determined activation energies for oxygen diffusion in the range of 0.19 eV (for epitaxial thin films) to 0.90 eV (for single crystals). 10,15,17 Interestingly, a number of diffusion mechanisms were proposed for the oxygen transport in this material. 6,10,15 A summary of these results is given in Table 1.…”

Section: Introductionmentioning

confidence: 99%

“…3,4 Additionally, the first members of the RP series with n = 1, A 2 BO 4 , that exhibit the K 2 NiF 4 structure are also being considered for oxygen sensors and oxygen separation membranes. [5][6][7][8][9][10][11][12][13][14][15][16][17] These materials have been extensively investigated since the observation of high-temperature superconductivity in La 2Àx Ba x CuO 4 . 18 An interesting and recent example of a composite SOFC cathode has been the work of Sase et al, 19 which demonstrated higher transport and an oxygen exchange rate that was higher by three orders of magnitude at the interface of the perovskite (La,Sr)CoO 3 and the RP phase (La,Sr) 2 CoO 4 .…”

Section: Introductionmentioning

confidence: 99%

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Interstitialcy diffusion of oxygen in tetragonal La₂CoO₄₊δ

Kushima

Parfitt

Chroneos

et al. 2011

Phys. Chem. Chem. Phys.

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105

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We report on the mechanism and energy barrier for oxygen diffusion in tetragonal La 2 CoO 4+d . The first principles-based calculations in the Density Functional Theory (DFT) formalism were performed to precisely describe the dominant migration paths for the interstitial oxygen atom in La 2 CoO 4+d . Atomistic simulations using molecular dynamics (MD) were performed to quantify the temperature dependent collective diffusivity, and to enable a comparison of the diffusion barriers found from the force field-based simulations to those obtained from the first principlesbased calculations. Both techniques consistently predict that oxygen migrates dominantly via an interstitialcy mechanism. The single interstitialcy migration path involves the removal of an apical lattice oxygen atom out from the LaO-plane and placing it into the nearest available interstitial site, whilst the original interstitial replaces the displaced apical oxygen on the LaO-plane. The facile migration of the interstitial oxygen in this path is enabled by the cooperative titling-untilting of the CoO 6 octahedron. DFT calculations indicate that this process has an activation energy significantly lower than that of the direct interstitial site exchange mechanism. For 800-1000 K, the MD diffusivities are consistent with the available experimental data within one order of magnitude. The DFT-and the MD-predictions suggest that the diffusion barrier for the interstitialcy mechanism is within 0.31-0.80 eV. The identified migration path, activation energies and diffusivities, and the associated uncertainties are discussed in the context of the previous experimental and theoretical results from the related Ruddlesden-Popper structures.

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Section: Temperature Dependent Collective Oxygen Diffusionmentioning

confidence: 46%

Section: Comparison With Experiments and Related Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Interstitialcy diffusion of oxygen in tetragonal La₂CoO₄₊δ

Kushima

Parfitt

Chroneos

et al. 2011

Phys. Chem. Chem. Phys.

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105

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“…2,3,[7][8][9][10] More recent studies highlight the potential of layered materials, such as Ruddlesden-Popper (RP) family of A n+1 B n O 3n+1 , as desirable cathodes due to their fast and anisotropic oxygen incorporation and transport properties. 6,[11][12][13][14] 15 Following up this study, Crumlin et al, using electrochemical impedance spectroscopy measurements, reported also an ORR activity enhancement up to about 10 3 -10 4 times at 550 °C on the thin film La 0.8 Sr 0.2 CoO 3-δ cathodes whose surfaces are decorated with (La 0.5 Sr 0.5 ) 2 CoO 4 islands (an thus, with a high density of LSC 113 /LSC 214 interfaces). 16 While it is evident that the interfacial regions are contributing to this unusually high ORR activity, the governing mechanism behind these empirical observations was not identified to date.…”

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.

113

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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Charge Transfer in Oxide Solid Fuel Cells

Shi

Yun

2020

Solid Oxide Fuel Cells

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Anisotropic oxygen diffusion in tetragonal La₂NiO_4+δ: molecular dynamics calculations

Cited by 208 publications

References 52 publications

Interstitialcy diffusion of oxygen in tetragonal La₂CoO₄₊δ

Interstitialcy diffusion of oxygen in tetragonal La₂CoO₄₊δ

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

Charge Transfer in Oxide Solid Fuel Cells

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Anisotropic oxygen diffusion in tetragonal La2NiO4+δ: molecular dynamics calculations

Cited by 208 publications

References 52 publications

Interstitialcy diffusion of oxygen in tetragonal La2CoO4+δ

Interstitialcy diffusion of oxygen in tetragonal La2CoO4+δ

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

Charge Transfer in Oxide Solid Fuel Cells

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Anisotropic oxygen diffusion in tetragonal La₂NiO_4+δ: molecular dynamics calculations

Interstitialcy diffusion of oxygen in tetragonal La₂CoO₄₊δ

Interstitialcy diffusion of oxygen in tetragonal La₂CoO₄₊δ