Experimental Evidence of Icosahedral and Decahedral Packing in One-Dimensional Nanostructures

Abstract

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 affect the chemical and structural properties of the material, and hence, its potential applications. This report describes the experimental formation of five-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 five-fold symmetry. These icosahedral nanowire structures remind those of quasicrystals that 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.

Advanced microscopy of star-shaped gold nanoparticles and their adsorption-uptake by macrophages

“…4,36,39,40 To probe this concept, we performed Raman spectroscopy of gold nanostars using rhodamine 6G as standard molecule. Spectra of gold nanoparticles coated with the fluorophore showed a significant increase of specific peaks assigned to rhodamine 6G (at 614, 774, 1129, 1183, 1310, 1363, 1509 and 1572 cm −1 ) in comparison with pure fluorophore on the same conditions (Fig.…”

Twisting Ultrathin Au Nanowires into Double Helices

“…Our group also reported the transformation of the straight Au‐Ag alloy nanowires to double helices . We believe the morphology transformation arises from the disruption of the double‐strand Boerdijk–Coxeter–Bernal (BCB) lattice, which was firstly observed in the oleylamine‐stabilized Au‐Ag nanowires synthesized with a coprecipitation process, and later also in coiled Au‐Cu nanowires . Upon coating of another metal (Au/Pt/Pd) layer onto the Au‐Ag nanowires, the thickened nanowire could not stand the strain and untwists in order to transform towards the more stable fcc lattice (the coating‐induced twisting).…”

Face the Edges: Catalytic Active Sites of Nanomaterials

“…f) FFT obtained along the axis of the nanowire of (c) showing the 5‐fold symmetry of Au nanowires. Reproduced with permission 175. Copyright 2011, American Chemical Society.…”

“…The nanowire is not atomic uniform along the wire, and the surface is not flat (Figure 10a, b) 174. The Ag‐Au alloy UNWs possess more complete structures with icosahedral and decahedral packing along the wire (Figure 10c–g) 175. The atomic structure of metal oxide UNWs might be more intricate, because their constitutions are even more complicated.…”