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Issue 13, 2015
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Correlation between structure and mixed ionic–electronic conduction mechanism for (La1−xSrx)CoO3−δ using synchrotron X-ray analysis and first principles calculations

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Abstract

The mechanism of mixed ionic–electronic conduction (MIEC) for (La1−xSrx)CoO3−δ (LSC) (x = 0.00–0.50) was investigated by experimental as well as theoretical studies which included Rietveld refinements, maximum entropy method (MEM) analysis, X-ray absorption spectroscopy, and first principles calculations (FPCs). The correlations among MIEC, structural parameters, i.e., the bond length, the bond angle, electron density, and the spin configuration, were discussed from the practical results. Moreover, these correlations were verified by FPC, and interpreted by the band structure and the total energy of LSC. The electronic conductivity was affected by the Co–O–Co bond angle, electron densities, and the spin state. In particular, the spin transition from the low to high spin state was accompanied by the cross-over from semiconductor to metallic at x = 0.15. Concerning the oxide ion diffusion, LSC has large anisotropic atomic displacement parameters of the oxide ion sites, in the vertical direction of the Co–O bond, which associate with the high oxide ion diffusion. The total energy of LSC during the migration of the oxide ion was also calculated with varying Sr content, lattice parameters, and symmetries by using FPC. Consequently, the symmetry of LSC is more effective to reduce the activation energy of oxide ion diffusion than Sr content and lattice parameters.

Graphical abstract: Correlation between structure and mixed ionic–electronic conduction mechanism for (La1−xSrx)CoO3−δ using synchrotron X-ray analysis and first principles calculations

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Publication details

The article was received on 23 Nov 2014, accepted on 01 Feb 2015 and first published on 02 Feb 2015


Article type: Paper
DOI: 10.1039/C4TA06386D
Author version available: Download Author version (PDF)
Citation: J. Mater. Chem. A, 2015,3, 6943-6953
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    Correlation between structure and mixed ionic–electronic conduction mechanism for (La1−xSrx)CoO3−δ using synchrotron X-ray analysis and first principles calculations

    T. Itoh, M. Inukai, N. Kitamura, N. Ishida, Y. Idemoto and T. Yamamoto, J. Mater. Chem. A, 2015, 3, 6943
    DOI: 10.1039/C4TA06386D

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