Zheng Haimei, Smith Rachel K, Jun Young-Wook, Kisielowski Christian, Dahmen Ulrich, Alivisatos A Paul
National Center for Electron Microcopy, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Science. 2009 Jun 5;324(5932):1309-12. doi: 10.1126/science.1172104.
Understanding of colloidal nanocrystal growth mechanisms is essential for the syntheses of nanocrystals with desired physical properties. The classical model for the growth of monodisperse nanocrystals assumes a discrete nucleation stage followed by growth via monomer attachment, but has overlooked particle-particle interactions. Recent studies have suggested that interactions between particles play an important role. Using in situ transmission electron microscopy, we show that platinum nanocrystals can grow either by monomer attachment from solution or by particle coalescence. Through the combination of these two processes, an initially broad size distribution can spontaneously narrow into a nearly monodisperse distribution. We suggest that colloidal nanocrystals take different pathways of growth based on their size- and morphology-dependent internal energies.
了解胶体纳米晶体的生长机制对于合成具有所需物理性质的纳米晶体至关重要。单分散纳米晶体生长的经典模型假定有一个离散的成核阶段，随后通过单体附着进行生长，但忽略了颗粒间的相互作用。最近的研究表明，颗粒间的相互作用起着重要作用。通过原位透射电子显微镜，我们表明铂纳米晶体可以通过从溶液中附着单体或通过颗粒聚结来生长。通过这两个过程的结合，最初较宽的尺寸分布可以自发地变窄为几乎单分散的分布。我们认为，胶体纳米晶体根据其尺寸和形态依赖的内能采取不同的生长途径。
