BaCe1-xPdxO3-δ (0 ≤ x ≤ 0.1): Redox controlled ingress and egress of palladium in a perovskite

Jun Li, Udayshankar G. Singh, Joseph W. Bennett, Katharine Page, James C. Weaver, Jin Ping Zhang, Thomas Proffen, Andrew M. Rappe, Susannah Scott, Ram Seshadri

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48 Scopus citations

Abstract

We demonstrate using a combination of X-ray and neutron diffraction and X-ray photoelectron spectroscopy that Pd2+ ions can be substituted for Ce in perovskite BaCeO3 and that, under oxidizing conditions, BaCe1-xPdxO3-δ (0 ≤ x ≤ 0.1) compositions can be prepared. Neutron diffraction has helped verify that δ ≈ x, implying that Ce4+ ions are substituted by Pd2+ and that a vacancy is concurrently created on the oxygen sublattice. The structure of the host compound and models for Pd substitution have also been studied using density functional theory, which has provided a detailed local description of the structure. The Pd2+-containing perovskite phases extrude elemental face-centered cubic palladium when heated in a reducing atmosphere. This elemental palladium is re-absorbed as ions into the perovskite lattice upon heating in flowing oxygen. Evidence for such cyclable ingress and egress of palladium under redox conditions is presented. A curious morphological change that results from the redox cycling of BaCe1-xPd xO3-δ is the formation of perovskite nanowires, which we believe to arise from regrowth of the perovskite around particles of elemental palladium.

Original languageEnglish
Pages (from-to)1418-1426
Number of pages9
JournalChemistry of Materials
Volume19
Issue number6
DOIs
StatePublished - Mar 20 2007
Externally publishedYes

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