In this paper, we propose the hypothesis that, in highly pure media, the cluster shape can be retained at various scales. Impurities and/or the additives can control the shape of the developing crystals by adsorption on selective sites. We demonstrate that the shape of clusters is retained at the nanoscale. This is supported by structural studies and both experiment and simulated optical properties of nanocrystal assemblies. We compare the data to those obtained by using a large variety of techniques and observation of crystal growth in nature.
Source : Control of the size and shape of inorganic nanocrystals at various scales from nano to macrodomains. M.P. Pileni J. Phys. Chem. C 111, 2007, 9019-9038