Structural instability of ultrafine particles of metals

Fluxionality of gold nanoparticles investigated by Born-Oppenheimer molecular dynamics

“…Nano-sized gold particles have been shown to possess a range of structures lying in a close energy range and to be fluxional at room temperature in the time scale of a few tens of picoseconds. The remarkable property of fluxionality for gold nano-clusters [36,38] is consistent with the structural instability of ultrafine metal particles observed by Iijima and Ichihashi and by Ajayan and Marks [43,44]. In our study fluxionality in the picoseconds regime, corresponding to the timescale of chemical reactivity, has been described for all the investigated systems, and local minima associated with specific numbers of atoms have been isolated and their geometrical and electronic properties have been analyzed and discussed.…”

Melting and equilibrium shape of icosahedral gold nanoparticles

“…While bulk gold has an fcc crystal structure, the competition between bulk and surface energies in nanometer sized gold crystallites can result in several different competing structures [6,7]. Depending on cluster size and external…”

“…It is therefore natural that the physics and chemistry of these materials are a current research subject of great interest [5]. For future applications knowledge of the structure and stability of gold nanoparticles of different size and morphology is particularly important.While bulk gold has an fcc crystal structure, the competition between bulk and surface energies in nanometer sized gold crystallites can result in several different competing structures [6,7]. Depending on cluster size and external…”

High Resolution Electron Microscopy of Carbonaceous Materials

“…All of these HRTEM studies have been the basis of the discovery of the CNTs. Another important study of HRTEM on the ultra-fine particles (in these days they are called nano-particles) should be mentioned, which I have worked on after returning to Japan, and developed the way of dynamic observation of nano-particles [6].There are several methods to characterize the atomic structures of CNTs; X-ray diffraction, Raman spectroscopy, Photo luminescence spectroscopy, Scanning probe microscopy, HRTEM, Electron diffraction. Among those methods HRTEM has become the most reliable one for analyzing individual nanotubes that were described by chiral indices, which define uniquely a nanotube structure.…”

“…All of these HRTEM studies have been the basis of the discovery of the CNTs. Another important study of HRTEM on the ultra-fine particles (in these days they are called nano-particles) should be mentioned, which I have worked on after returning to Japan, and developed the way of dynamic observation of nano-particles [6].…”