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Ultra-thin films and surface alloying of Pd on Cu(1 1 1) investigated by medium energy ion scattering

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journal contribution
posted on 19.07.2011, 13:54 authored by Christopher J. Howe, Michael CropperMichael Cropper, Thomas P. Fleming, Richard M. Wardle, P. Bailey, T.C.Q. Noakes
The structure of Pd films on Cu(1 1 1) and the alloying between the films and the substrate have been investigated by medium energy ion scattering (MEIS) using 100 keV H+ ions. Data are presented for the ½ 1 10 and ½ 1 1 4 alignments (nominal one- and three-layer alignments, respectively). It is found that beyond 1 ML the Pd grows in a twinned fcc structure, the incommensurate nature of which increases the visibility of the Cu(1 1 1) substrate to MEIS. Deposition of 0.2 ML of Pd produces a structure in which Pd mostly occupies the top two layers which have interlayer distances d12 = 208 ± 4 pm and d23 = 211 ± 4 pm. Some twinning is also present in this structure. Upon annealing 1.6 ML of Pd to 600 K for 1 min, the copper and palladium interdiffuse leaving around 0.4 ML of visible palladium. Energy plots show that there are several layers with an altered structure present over at least part of the surface. This may be due to large scale interdiffusion or alloy island formation. Incremental annealing to successively higher temperatures shows that the structural transformation begins around 500K.

History

School

  • Science

Department

  • Physics

Citation

HOWE, C.J. ... et al, 2010. Ultra-thin films and surface alloying of Pd on Cu(1 1 1) investigated by medium energy ion scattering. Surface Science, 604 (2), pp. 201-209.

Publisher

© Elsevier

Version

AM (Accepted Manuscript)

Publication date

2010

ISSN

0039-6028

Language

en