Dresden 2003 – wissenschaftliches Programm
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M: Metallphysik
M 8: Quasikristalle II
M 8.4: Vortrag
Montag, 24. März 2003, 12:30–12:45, IFW B
RHEED and SPM investigations of Quasicrystals and Approximants — •Christina Cecco1, Manfred Albrecht2, Georg Krausch3, Günter Schatz4 und Walter Steurer5 — 1Department Chemie, LMU München, Butenandtstr. 11, 81377 München, Germany — 2IBM Almaden Research Center, Dept. K11 D1-428, 650 Harry Road, San Jose, CA, 95120, USA — 3Physikalische Chemie II, Universität Bayreuth, D-95440 Bayreuth — 4Fakultät für Physik, Universität Konstanz, P.O. Box M621, 78457 Konstanz, Germany — 5Institut für Kristallographie, Department für Materialwissenschaften, ETH Zürich, CH-8092 Zürich, Switzerland
Complex alloy structures may undergo a structural phase transition in the near-surface region induced by Ar+-bombardment due to preferential sputtering of selective components. This can lead to the presence of a crystalline overlayer after the sputtering process. Annealing induces enhanced diffusion and hence the recovery of the surface composition, which leads to a second phase transition back to the bulk structure of the quasicrystal or approximant under investigation. The behaviour of the tenfold surface and the twofold (10000)-surface of decagonal Al-Ni-Co quasicrystals will be discussed. The twofold surface is showing diffraction from inclined netplanes. In addition, the system Al-Pd-Mn was under investigation: the behaviour of the fivefold and the twofold surface of an icosahedral Al-Pd-Mn quasicrystal and the pseudo-tenfold surface of an ξ’-(Al-Pd-Mn) approximant will be shown. The results will be compared to topographical studies by scanning probe microscopy methods (SFM,STM).