Nonclassical Recrystallization |
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Authors: | Dr Julian Brunner Britta Maier Rose Rosenberg Sebastian Sturm Prof Dr Helmut Cölfen Dr Elena V Sturm |
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Institution: | 1. Physical Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany;2. Institute for Solid State Research, Leibniz Institute for Solid State and Materials Research Dresden, Helmholzstraße 20, 01069 Dresden, Germany |
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Abstract: | Applications in the fields of materials science and nanotechnology increasingly demand monodisperse nanoparticles in size and shape. Up to now, no general purification procedure exists to thoroughly narrow the size and shape distributions of nanoparticles. Here, we show by analytical ultracentrifugation (AUC) as an absolute and quantitative high-resolution method that multiple recrystallizations of nanocrystals to mesocrystals is a very efficient tool to generate nanocrystals with an excellent and so-far unsurpassed size-distribution (PDIc=1.0001) and shape. Similar to the crystallization of molecular building blocks, nonclassical recrystallization removes “colloidal” impurities (i.e., nanoparticles, which are different in shape and size from the majority) by assembling them into a mesocrystal. In the case of nanocrystals, this assembly can be size- and shape-selective, since mesocrystals show both long-range packing ordering and preferable crystallographic orientation of nanocrystals. Besides the generation of highly monodisperse nanoparticles, these findings provide highly relevant insights into the crystallization of mesocrystals. |
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Keywords: | analytical ultracentrifugation mesocrystals nanocrystals recrystallization size separation |
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