Self-similarity during growth of the Au/TiO{sub 2}(110) model catalyst as seen by the scattering of x-rays at grazing-angle incidence

Journal Article · Sat Sep 15 00:00:00 EDT 2007 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.76.125412· OSTI ID:21055171

Lazzari, Remi; Jupille, Jacques ^[1]; Renaud, Gilles ^[2]; Leroy, Frederic ^[3]

---

1. Institut des NanoSciences de Paris, Universites Pierre et Marie Curie (Paris 6) et Denis Diderot (Paris 7), CNRS UMR 7588 Campus Boucicaut, 140 Rue de Lourmel, 75015 Paris (France)
2. Nanostructures et Rayonnement Synchrotron, Service de Physique des Materiaux et Microstructures, Departement de Recherche Fondamentale sur la Matiere Condensee, Commissariat a l'Energie Atomique, 17 Avenue des Martyrs, F-38054 Grenoble, Cedex 9 (France)
3. Centre de Recherche en Matiere Condensee et NanoSciences, CNRS-UPR 7281, Campus de Luminy Case 913, 13288 Marseille Cedex 09 (France)

The growth of gold nanoparticles on TiO{sub 2}(110) was investigated in situ by grazing incidence x-ray scattering techniques. The in-plane diffraction showed complex epitaxial relationships with a preferential alignment of dense gold direction along the bridging oxygen rows of TiO{sub 2}(110) ([110]{sub Au} parallel [001]{sub TiO{sub 2}}) with a low lattice mismatch. Whatever the growth temperature (T=300,600 K), two nearly equiproportional epitaxial planes, i.e., (111){sub Au} parallel (110){sub TiO{sub 2}} and (112){sub Au} parallel (110){sub TiO{sub 2}}, were observed. The small angle scattering from the nanoparticles was analyzed using a truncated sphere shape with models [R. Lazzari, F. Leroy, and G. Renaud, Phys. Rev. B 76, 125411 (2007)] that account for (i) multiple scattering effects due to the graded profile of refraction index in the normal direction and (ii) the correlation between the particle spacing and sizes. At the beginning of the growth, gold particles are pinned on defects and grow through a diffusion-limited mechanism. However, coalescence does not occur via a static mechanism. It rather involves surface diffusion of clusters. It proceeds through a self-similar mechanism, not only on the size distribution but also on the spatial ordering. Particle locations, which are no longer controlled by the randomness of nucleation centers, become dominated by the correlation between the particle size and its influence area. A strong link between island height and radius indicates that particles are close to equilibrium. Indeed, the value derived for contact angle (adhesion energy) compares well with tabulated data. In addition, the cluster size before the onset of coalescence compares with that of the gold particles at the maximum of catalytic activity for the oxidation of CO.

• OSTI ID: 21055171
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 12 Vol. 76; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARBON MONOXIDE
CATALYSTS
COALESCENCE
COMPARATIVE EVALUATIONS
CRYSTAL DEFECTS
DIFFUSION
EPITAXY
GOLD
INCIDENCE ANGLE
MULTIPLE SCATTERING
NANOSTRUCTURES
OXYGEN
PARTICLE SIZE
PARTICLES
SMALL ANGLE SCATTERING
SURFACES
TEMPERATURE DEPENDENCE
TITANIUM OXIDES
X RADIATION
X-RAY DIFFRACTION