Regensburg 2002 – wissenschaftliches Programm

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M: Metallphysik

M 9: Quasikristalle II

M 9.2: Fachvortrag

Dienstag, 12. März 2002, 11:45–12:00, H6

Bulk Termination of the Quasicrystalline Five-Fold Surface of Al(70)Pd(21)Mn(9) — •Gerald Kasner and Zorka Papadopolos — Institut für Theoretische Physik, Universität Magdeburg, PF 2140, D-39016 Magdeburg

The structure of the Al₇₀Pd₂₁Mn₉ surface has been investigated using high resolution scanning tunnelling microscopy (STM), and an atomically resolved surface has been imaged. The location of this surface-plane has been estimated in the bulk model M for icosahedral (i)-AlPdMn based on the three-dimensional tiling T^*(2F) for an F-phase. The high resolution STM image of the surface allows the position of the bulk terminations to be fixed within the layers of Bergman polytopes in the model M. They are 4.08 Å in the direction of the bulk from a surface of the most dense Bergman layers. The average atomic density of terminations consisting of two plane-layers at the new positions is consistent with the results of Gierer et al. From the coding window of the model M-termination-plane we estimate the shortest edge of a possible tiling by Penrose (P1) prototiles to be 7.8 Å. The experimentally derived tiling of the surface has edge length 8.0 ± 0.3 Å and hence matches edge-length expected from the model.