Bulk termination of the quasicrystalline fivefold surface of Al70Pd21Mn9

The structure of the Al70Pd21Mn9 surface has been investigated using high-resolution scanning tunneling microscopy. From two large fivefold terraces on the surface in a short decorated Fibonacci sequence, atomically resolved surface images have been obtained. One of these terraces carries a rare local configuration in the form of a ring. The location of the corresponding sequence of terminations in the bulk model M of icosahedral i-AlPdMn based on the three-dimensional tiling T*(2F) of an F phase has been estimated using this ring configuration and the requirement from low-energy electron diffraction work of Gierer et al. that the average atomic density of the terminations is 0.136 atoms per Å2. A termination contains two atomic plane layers separated by a vertical distance of 0.48 Å. The position of the bulk terminations is 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. From the coding windows of the top planes in terminations in M we conclude that a Penrose (P1) tiling is possible on almost all fivefold terraces. The shortest edge of the tiling P1 is either 4.8 or 7.8 Å. The experimentally derived tiling of the surface with the ring configuration has an edge length of 8.0±0.3Å and hence matches the minimal edge length expected from the model. Disciplines Condensed Matter Physics | Metallurgy Comments This article is from Physical Review B 66 (2002): 184207, doi:10.1103/PhysRevB.66.184207. Authors Z. Papadopolos, G. Kasner, J. Ledieu, E. J. Cox, N. V. Richardson, Q. Chen, R. D. Diehl, Thomas A. Lograsso, A. R. Ross, and R. McGrath This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/ameslab_pubs/113 Bulk termination of the quasicrystalline fivefold surface of Al70Pd21Mn9 Z. Papadopolos* and G. Kasner Institut für Theoretische Physik, Universität Magdeburg, PSF 4120, D-39016 Magdeburg, Germany J. Ledieu and E. J. Cox Surface Science Research Centre, The University of Liverpool, Liverpool L69 3BX, United Kingdom N. V. Richardson and Q. Chen Department of Chemistry, University of St. Andrews, Fife, Scotland R. D. Diehl Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 T. A. Lograsso and A. R. Ross Ames Laboratory, Iowa State University, Ames, Iowa 50011 R. McGrath Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX, United Kingdom ~Received 25 November 2001; published 18 November 2002! The structure of the Al70Pd21Mn9 surface has been investigated using high-resolution scanning tunneling microscopy. From two large fivefold terraces on the surface in a short decorated Fibonacci sequence, atomically resolved surface images have been obtained. One of these terraces carries a rare local configuration in the form of a ring. The location of the corresponding sequence of terminations in the bulk model M of icosahedral i-AlPdMn based on the three-dimensional tiling T *(2F) of an F phase has been estimated using this ring configuration and the requirement from low-energy electron diffraction work of Gierer et al. that the average atomic density of the terminations is 0.136 atoms per Å. A termination contains two atomic plane layers separated by a vertical distance of 0.48 Å. The position of the bulk terminations is 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. From the coding windows of the top planes in terminations in M we conclude that a Penrose ~P1! tiling is possible on almost all fivefold terraces. The shortest edge of the tiling P1 is either 4.8 or 7.8 Å. The experimentally derived tiling of the surface with the ring configuration has an edge length of 8.0 60.3 Å and hence matches the minimal edge length expected from the model. DOI: 10.1103/PhysRevB.66.184207 PACS number~s!: 61.44.Br, 68.35.Bs, 68.37.Ef, 61.14.Hg