Stabilization of the PdIn(111) surface via oxygen adsorption—studied by high−resolution electron energy loss spectroscopy and scanning tunneling microscopy

Franchy, R.; Schmitz, Guido

doi:10.1209/epl/i2000-00371-6

Cited by 2 publications

(1 citation statement)

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“…A previous report by Franchy and Schmitz examined the InPd(111) single crystal surface under ultrahigh vacuum (UHV) conditions. 31 A clean surface was prepared by cycles of Ar + sputtering and annealing to 1070 K and produced a (1 × 1) LEED pattern of poor quality with broadened reflections, manifested by triangulated distortions of (h,k) spots and suggesting faceting. The surface was found very rough by STM.…”

Section: Introductionmentioning

confidence: 99%

The atomic structure of low-index surfaces of the intermetallic compound InPd

McGuirk

Ledieu

Gaudry

et al. 2015

The Journal of Chemical Physics

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The intermetallic compound InPd (CsCl type of crystal structure with a broad compositional range) is considered as a candidate catalyst for the steam reforming of methanol. Single crystals of this phase have been grown to study the structure of its three low-index surfaces under ultra-high vacuum conditions, using low energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy (STM). During surface preparation, preferential sputtering leads to a depletion of In within the top few layers for all three surfaces. The near-surface regions remain slightly Pd-rich until annealing to ∼580 K. A transition occurs between 580 and 660 K where In segregates towards the surface and the near-surface regions become slightly In-rich above ∼660 K. This transition is accompanied by a sharpening of LEED patterns and formation of flat step-terrace morphology, as observed by STM. Several superstructures have been identified for the different surfaces associated with this process. Annealing to higher temperatures (≥750 K) leads to faceting via thermal etching as shown for the (110) surface, with a bulk In composition close to the In-rich limit of the existence domain of the cubic phase. The Pd-rich InPd(111) is found to be consistent with a Pd-terminated bulk truncation model as shown by dynamical LEED analysis while, after annealing at higher temperature, the In-rich InPd(111) is consistent with an In-terminated bulk truncation, in agreement with density functional theory (DFT) calculations of the relative surface energies. More complex surface structures are observed for the (100) surface. Additionally, individual grains of a polycrystalline sample are characterized by micro-spot XPS and LEED as well as low-energy electron microscopy. Results from both individual grains and "global" measurements are interpreted based on comparison to our single crystals findings, DFT calculations and previous literature.

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Section: Introductionmentioning

confidence: 99%