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DOE OSTI · 1364000

Low-Dimensional Oxygen Vacancy Ordering and Diffusion in SrCrO 3$-$δ

Ong, Phuong-Vu (ORCID:0000000186131690)·Du, Yingge·Sushko, Peter V.
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Abstract

We investigate the formation mechanisms of vacancy-ordered phase and collective mass transport in epitaxial SrCrO 3$-$δ films using ab initio simulations within the density functional theory formalism. We show that as concentration of oxygen vacancies (V O ’s) increases, they form one-dimensional (1D) chains that feature Cr-centered tetrahedra. Aggregation of these 1D V O -chains results in the formation of (111)-oriented oxygen-deficient planes (V O -planes) and an extended vacancy-ordered phase observed in recent experiments. We discuss atomic scale mechanisms enabling the quasi-2D V O aggregates to expand along and translate across (111) planes. The corresponding lowest activation energy pathways necessarily involve rotation of Cr-centered tetrahedra, which emerges as a universal feature of fast ionic conduction in complex oxides. These findings explain reversible oxidation and reduction in SrCrO 3$-$δ at low-temperatures and provide insights into transient behavior necessary to harness ionic conductive oxides for high performance and low-temperature electrochemical reactors.

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density functional theoryDiffusionOxidesTwo-dimensionalVacancy ordering

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Ong, Phuong-Vu (ORCID:0000000186131690), Du, Yingge, Sushko, Peter V.. 2017-04-06. Low-Dimensional Oxygen Vacancy Ordering and Diffusion in SrCrO 3$-$δ. https://doi.org/10.1021/acs.jpclett.7b00355

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