Adsorption sites on icosahedral quasicrystal surfaces: dark stars and white flowers
Adsorption sites on icosahedral quasicrystal surfaces: dark stars and white flowers
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二十面体准晶表面的吸附位点：暗星和白花
DOI：
10.1088/0953-8984/21/5/055009
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Patricia A. Thiel
中科院分区：
文献类型：
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作者：
Barış Ünal;Barış Ünal;C. Jenks;Patricia A. Thiel;Patricia A. Thiel
从其他工作中，已经提出了金属和半金属在二十面体铝基准晶体的五重表面吸附的两个优选位置。由于它们在扫描隧道显微镜（STM）图像中的外观，这些位置被称为暗星和白花。在本文中，我们分析了物理空间中的四种体结构模型，以确定暗星的类型、化学装饰和密度，以及在较小程度上确定二十面体Al-Pd-Mn的五重面白花吸附位点。我们发现这些位点的化学修饰是异质的，即使在一个模型中也是如此。根据STM测量，这两个特征在结构上也是不均匀的，结构变化与体结构模型一致。最后，从模型中，暗星在平面上的密度与台阶高度相关。这也许可以解释以前不同梯田的不同性质的实验观察。
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.