Department of Physics and Astronomy, The University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249, USA.
ACS Nano. 2011 Aug 23;5(8):6272-8. doi: 10.1021/nn202495r. Epub 2011 Aug 1.
The packing of spheres is a subject that has drawn the attention of mathematicians and philosophers for centuries and that currently attracts the interest of the scientific community in several fields. At the nanoscale, the packing of atoms affects the chemical and structural properties of the material and, hence, its potential applications. This report describes the experimental formation of 5-fold nanostructures by the packing of interpenetrated icosahedral and decahedral units. These nanowires, formed by the reaction of a mixture of metal salts (Au and Ag) in the presence of oleylamine, are obtained when the chemical composition is specifically Ag/Au = 3:1. The experimental images of the icosahedral nanowires have a high likelihood with simulated electron micrographs of structures formed by two or three Boerdijk-Coxeter-Bernal helices roped on a single structure, whereas for the decahedral wires, simulations using a model of adjacent decahedra match the experimental structures. To our knowledge, this is the first report of the synthesis of nanowires formed by the packing of structures with 5-fold symmetry. These icosahedral nanowire structures are similar to those of quasicrystals, which can only be formed if at least two atomic species are present and in which icosahedral and decahedral packing has been found for bulk crystals.
球体的堆积是一个引起数学家和哲学家几个世纪关注的主题，也是目前多个领域科学界感兴趣的主题。在纳米尺度上，原子的堆积会影响材料的化学和结构特性，从而影响其潜在的应用。本报告描述了通过互穿的二十面体和截角二十面体单元的堆积形成 5 重结构的实验。这些纳米线是通过混合金属盐（金和银）在油胺存在下反应形成的，当化学组成特定为 Ag/Au=3:1 时就会得到。实验得到的二十面体纳米线的图像与由两个或三个 Boerdijk-Coxeter-Bernal 螺旋缠绕在单个结构上形成的结构的模拟电子显微镜图像高度吻合，而对于截角二十面体纳米线，使用相邻截角二十面体模型的模拟与实验结构匹配。据我们所知，这是首次报道通过具有 5 重对称结构的堆积来合成纳米线。这些二十面体纳米线结构类似于准晶体，只有在存在至少两种原子物种的情况下才能形成，并且在大块晶体中已经发现了二十面体和截角二十面体的堆积。
