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Issue 17, 2013
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Oxide ion transport in Sr2Fe1.5Mo0.5O6−δ, a mixed ion-electron conductor: new insights from first principles modeling

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Abstract

We use ab initio density functional theory + U calculations to characterize the oxide ion diffusion process in bulk Sr2Fe1.5Mo0.5O6−δ (SFMO) by analyzing the formation and migration of oxygen vacancies. We show that SFMO's remarkable ionic conductivity arises from its intrinsic content of oxygen vacancies and a predicted very low migration barrier of such vacancies. Theoretical analysis of the electronic structure reveals a crucial role played by strongly hybridized Fe 3d/O 2p states to achieve the attendant mixed ion-electron conductor character so important for intermediate temperature fuel cell operation. We predict a next-nearest-neighbor-type migration pathway for the O2− ion should dominate. The low energy barrier of this pathway is mainly related to electrostatic interactions with homogeneously distributed Mo in the SFMO sublattice. We identify the reasons why Fe-rich perovskites, with the key addition of a certain concentration of Mo, produce excellent electronic and ionic transport properties so crucial for efficient operation of intermediate temperature solid oxide fuel cells.

Graphical abstract: Oxide ion transport in Sr2Fe1.5Mo0.5O6−δ, a mixed ion-electron conductor: new insights from first principles modeling

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Publication details

The article was received on 06 Mar 2013, accepted on 07 Mar 2013 and first published on 07 Mar 2013


Article type: Paper
DOI: 10.1039/C3CP50995H
Citation: Phys. Chem. Chem. Phys., 2013,15, 6250-6259
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    Oxide ion transport in Sr2Fe1.5Mo0.5O6−δ, a mixed ion-electron conductor: new insights from first principles modeling

    A. B. Muñoz-García, M. Pavone, A. M. Ritzmann and E. A. Carter, Phys. Chem. Chem. Phys., 2013, 15, 6250
    DOI: 10.1039/C3CP50995H

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