Department of Chemistry, 207 Pleasant Street SE, University of Minnesota, Minneapolis, Minnesota 55455, USA.
J Am Chem Soc. 2010 Feb 24;132(7):2163-5. doi: 10.1021/ja909769a.
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.
取向聚集是聚集的一种特殊情况，其中纳米晶体自组装并形成新的二次单晶。据推测，这个过程是通过一种中间状态进行的，称为介晶，其中纳米晶体具有平行的晶体取向，但在空间上是分离的。我们通过使用 cryo-TEM 直接对水悬浮液中的颗粒进行成像，首次直接观察到与产物定向聚集相似的大小和形状的介晶。 cryo-TEM 图像表明，介晶不仅在分散状态下形成，而且还转化为最终的单晶产物。此外，高分辨率 cryo-TEM 图像表明，介晶由空间分离和结晶排列的纳米晶体组成。
