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Anomalous Interface and Surface Strontium Segregation in (La1–ySry)2CoO4±δ/La1–xSrxCoO3−δ Heterostructured Thin Films
journal contribution
posted on 2015-12-17, 01:08 authored by Zhenxing Feng, Yizhak Yacoby, Milind J. Gadre, Yueh-Lin Lee, Wesley T. Hong, Hua Zhou, Michael
D. Biegalski, Hans M. Christen, Stuart B. Adler, Dane Morgan, Yang Shao-HornHeterostructured
oxides have shown unusual electrochemical properties
including enhanced catalytic activity, ion transport, and stability.
In particular, it has been shown recently that the activity of oxygen
electrocatalysis on the Ruddlesden–Popper/perovskite (La1‑ySry)2CoO4±δ/La1–xSrxCoO3−δ heterostructure is remarkably enhanced relative to the Ruddlesden–Popper
and perovskite constituents. Here we report the first atomic-scale
structure and composition of (La1–ySry)2CoO4±δ/La1–xSrxCoO3−δ grown on SrTiO3.
We observe anomalous strontium segregation from the perovskite to
the interface and the Ruddlesden–Popper phase using direct
X-ray methods as well as with ab initio calculations. Such Sr segregation
occurred during the film growth, and no significant changes were found
upon subsequent annealing in O2. Our findings provide insights
into the design of highly active catalysts for oxygen electrocatalysis.