GROWTH OF METAL NANO-CLUSTERS ON METAL AND OXIDE SURFACES: A RHEED STUDY
The powerful RHEED technique has been demonstrated for the structural determination of the nano-crystals grown on metal and oxide substrate surfaces. Pt was electrochemically deposited onto a $Ru(10\bar{1}0)$ electrode, while Pb and cobalt were vapor deposited onto Ag(111) and oxide film/NiAl(100), respectively under UHV conditions. At any Pt coverage, 3D-clusters develop for which the Pt clusters grow in (311) orientation on the $Ru(10\bar{1}0)$ substrate surface, where the $[01\bar{1}]$ atomic rows of the (311) facet are parallel to the $[1\bar{2}10]$ atomic rows of the $Ru(10\bar{1}0)$ surface. Due to the strong bonding at Pb/Ag(111) interface, the Pb deposit grows in 2D-islands with a $(\sqrt{3} \times \sqrt{3})R30^{\circ}$ phase (Θ < 1 ML). On the other hand, the β-crystallites of ≈ 1 nm in diameter with inclusion of smaller-sized particles (D < 1 nm) are observed on Θ-Al2O3 after Co deposition at room temperature. Annealing at 900 K Co clusters (≈ 3 nm) grow larger at expense of small particles on thin oxide film on NiAl(100) and become better ordered, where the [110] axis of the Co(001) facet is parallel to the [100] direction of the (001)-oxide surface. The in-plane lattice constant of Co clusters is ca. 4 larger than that of bulk Co, yielding less strain at the (001)-oxide surface. These results demonstrate that both orientation and phase of metal nano-clusters are governed by surface structure of the substrate.
Year of publication: |
2007
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Authors: | ZEI, M. S. |
Published in: |
Surface Review and Letters (SRL). - World Scientific Publishing Co. Pte. Ltd., ISSN 1793-6667. - Vol. 14.2007, 04, p. 729-734
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Publisher: |
World Scientific Publishing Co. Pte. Ltd. |
Subject: | Reflection high-energy electron diffraction (RHEED) | auger electron spectroscopy | cobalt | platinum | lead | ruthenium | aluminum oxide | clusters |
Saved in:
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