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Phys. Rev. B 58, 9961–9971 (1998)

Crystalline surface structures induced by ion sputtering of Al-rich icosahedral quasicrystals

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Z. Shen
Ames Laboratory of the DOE and Department of Chemistry, Iowa State University, Ames, Iowa 50011

M. J. Kramer
Ames Laboratory of the DOE and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011

C. J. Jenks
Ames Laboratory of the DOE, Iowa State University, Ames, Iowa 50011

A. I. Goldman
Ames Laboratory of the DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011

T. Lograsso
Ames Laboratory of the DOE and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011

D. Delaney
Ames Laboratory of the DOE, Iowa State University, Ames, Iowa 50011

M. Heinzig
Ames Laboratory of the DOE and Department of Chemistry, Iowa State University, Ames, Iowa 50011

W. Raberg
Institut für Physikalische Chemie, Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany

P. A. Thiel*
Ames Laboratory of the DOE and Department of Chemistry, Iowa State University, Ames, Iowa 50011

Received 28 May 1998; published in the issue dated 15 October 1998

Low-energy electron diffraction patterns, produced from quasicrystal surfaces by ion sputtering and annealing to temperatures below ∼700 K, can be assigned to various terminations of the cubic CsCl structure. The assignments are based upon ratios of spot spacings, estimates of surface lattice constants, bulk phase diagrams vs surface compositions, and comparisons with previous work. The CsCl overlayers are deeper than about five atomic layers, because they obscure the diffraction spots from the underlying quasicrystalline substrate. These patterns transform irreversibly to quasicrystalline(like) patterns upon annealing to higher temperatures, indicating that the cubic overlayers are metastable. Based upon the data for three chemically identical, but symmetrically inequivalent surfaces, a model is developed for the relation between the cubic overlayers and the quasicrystalline substrate. The model is based upon the related symmetries of cubic close-packed and icosahedral-packed materials. The model explains not only the symmetries of the cubic surface terminations, but also the number and orientation of domains.

© 1998 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.58.9961
DOI:
10.1103/PhysRevB.58.9961
PACS:
61.44.Br, 68.35.Bs, 61.14.Hg, 81.10.Aj

*Author to whom correspondence should be addressed. FAX: 515-294-4709. Electronic address: thiel@ameslab.gov

 
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