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

Autor:	Ong PV; Physical Sciences Division, Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States., Du Y; Physical Sciences Division, Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States., Sushko PV; Physical Sciences Division, Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
Jazyk:	angličtina
Zdroj:	The journal of physical chemistry letters [J Phys Chem Lett] 2017 Apr 20; Vol. 8 (8), pp. 1757-1763. Date of Electronic Publication: 2017 Apr 06.
DOI:	10.1021/acs.jpclett.7b00355
Abstrakt:	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 the concentration of oxygen vacancies (V O ) increases, they form 1D chains that feature Cr-centered tetrahedra. Aggregation of these 1D V O chains results in the formation of (111)-oriented oxygen-deficient 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.
Databáze:	MEDLINE
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