02/05/2010
Oriented Aggregation: Formation and Transformation of Mesocrystal Intermediates Revealed
Recent research from the research group of Professor R. Lee Penn.
Oriented aggregation is a special case of
aggregation in which nanocrystals self-assemble and form new secondary single
crystals. This process has been suggested to proceed via an intermediate state
known as the mesocrystal, in which the nanocrystals have parallel
crystallographic alignment but are spatially separated. We present the first
direct observations of mesocrystals with size and shape similar to product
oriented aggregates by employing cryo-TEM to directly image the particles in
aqueous suspension. The cryo-TEM images reveal that mesocrystals not only form
but also transform to the final single crystal product while in the dispersed
state. Further, high-resolution cryo-TEM images demonstrate that the
mesocrystals are composed of spatially separated and crystallographically aligned
nanocrystals.
Link to article: http://pubs.acs.org/doi/full/10.1021/ja909769a
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