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Issue 21, 2014
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Ab initio DFT+U analysis of oxygen transport in LaCoO3: the effect of Co3+ magnetic states

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Abstract

Although solid oxide fuel cells (SOFCs) provide clean and efficient electricity generation, high operating temperatures (T > 800 °C) limit their widespread use. Lowering operating temperatures (600 °C < T < 800 °C) requires developing next-generation mixed ion-electron conducting (MIEC) cathodes that permit facile oxygen transport. One promising MIEC material, La1−xSrxCo1−yFeyO3 (LSCF), can operate at intermediate temperatures, has a longer cell lifetime, and permits less expensive interconnect materials. However, the road to optimization of LSCF compositions for SOFC applications would benefit from fundamental, atomic-scale insight into how local chemical changes affect its oxygen ion conductivity. We provide this insight using ab initio density functional theory plus U (DFT+U) calculations to analyze the factors governing oxygen transport in the LSCF parent material LaCoO3. We show that oxygen diffusion in LaCoO3 depends strongly on the spin state of the Co3+ ions: in particular, low spin Co3+ promotes higher oxygen vacancy concentrations than other spin states. We also predict that different spin states of Co3+ significantly affect the oxygen ion migration barrier. Through electronic structure analysis, we uncover the fundamental details which govern oxygen diffusivity in LaCoO3.

Graphical abstract: Ab initio DFT+U analysis of oxygen transport in LaCoO3: the effect of Co3+ magnetic states

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Publication details

The article was received on 15 Feb 2014, accepted on 06 Apr 2014 and first published on 08 Apr 2014


Article type: Paper
DOI: 10.1039/C4TA00801D
Author version available: Download Author version (PDF)
Citation: J. Mater. Chem. A, 2014,2, 8060-8074
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    Ab initio DFT+U analysis of oxygen transport in LaCoO3: the effect of Co3+ magnetic states

    A. M. Ritzmann, M. Pavone, A. B. Muñoz-García, J. A. Keith and E. A. Carter, J. Mater. Chem. A, 2014, 2, 8060
    DOI: 10.1039/C4TA00801D

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