Adsorption sites on icosahedral quasicrystal surfaces: dark stars and white flowers

TitleAdsorption sites on icosahedral quasicrystal surfaces: dark stars and white flowers
Publication TypeJournal Article
Year of Publication2009
AuthorsUnal B, Jenks CJ, Thiel PA
Journal TitleJournal of Physics-Condensed Matter
Volume21
Pages055009
Date Published02/04
ISBN Number0953-8984
Accession NumberISI:000262375100011
Keywordsal-pd-mn, al70pd21mn9, alpdmn, atoms, deposition, energy-electron diffraction, fivefold surface, growth, nucleation, scanning-tunneling-microscopy
Abstract

From other work, two preferred sites have been suggested for metals and semimetals adsorbed on the fivefold surfaces of icosahedral, Al-based quasicrystals. Because of their appearance in scanning tunneling microscopy (STM) images, these sites are known as dark stars and white flowers. In this paper, we analyze four bulk structural models in physical space to determine the types, chemical decorations, and densities of the dark star-and, to a lesser extent, the white flower-adsorption sites for the fivefold planes of icosahedral Al-Pd-Mn. We find that the chemical decorations of these sites are heterogeneous, even within a single model. Both features are also structurally heterogeneous, according to STM measurements, and the structural variation is consistent with the bulk structure models. Finally, from the models, the density of dark stars in the planes correlates with the step height. This may explain previous experimental observations of different properties for different terraces.

URL<Go to ISI>://000262375100011
DOI10.1088/0953-8984/21/5/055009