Element-specific structure of materials with intrinsic disorder by high-energy resonant x-ray diffraction and differential atomic pair-distribution functions: A study of PtPd nanosized catalysts

V. Petkov, S. D. Shastri

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Abstract

We demonstrate how high-energy resonant x-ray diffraction (XRD) and differential atomic-pair-distribution function (PDF) analysis can be used to characterize the atomic ordering in materials of limited structural coherence with both excellent spatial resolution and element specificity. First we prove that this experimental approach is feasible by probing the K -absorption edge of Au (∼81 keV) atoms in chemically ordered and disordered bulk Cu3 Au alloys. The resulting Au-differential PDFs show very clearly the different ways Au atoms are known to occupy the sites of otherwise identical cubic lattices of those materials. Next we apply it to a more complex material: PtPd alloy and core-shell nanosized (∼2-4 nm) particles by probing the K -absorption edge of Pt (∼78 keV). The resulting Pt-differential atomic PDFs reveal how exactly the atomic ordering of catalytically active Pt atoms is affected by the nanoparticles' design, thus providing a firm structural basis for understanding their properties. The work is a step forward in expanding the limits of applicability of nontraditional XRD to the rapidly growing field of materials of unusual structural complexity.

Original languageEnglish
Article number165428
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume81
Issue number16
DOIs
StatePublished - Apr 21 2010

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