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

Abstract : 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.
Type de document :
Article dans une revue
Journal of Chemical Physics, American Institute of Physics, 2015
Liste complète des métadonnées

Littérature citée [39 références]  Voir  Masquer  Télécharger
Contributeur : Emilie Gaudry <>
Soumis le : mercredi 21 octobre 2015 - 09:09:50
Dernière modification le : lundi 29 octobre 2018 - 09:54:01
Document(s) archivé(s) le : vendredi 22 janvier 2016 - 18:23:38


Fichiers éditeurs autorisés sur une archive ouverte


  • HAL Id : hal-01218362, version 1



G. M. Mcguirk, J. Ledieu, É. Gaudry, M.-C. De Weerd, M. Hahne, et al.. The atomic structure of low-index surfaces of the intermetallic compound InPd. Journal of Chemical Physics, American Institute of Physics, 2015. 〈hal-01218362〉



Consultations de la notice


Téléchargements de fichiers