Self-assembly of shape-controlled nanocrystals and their in-situ thermodynamic properties

Size and shape selected nanocrystals behave like molecular matter that can be used as fundamental building blocks for constructing nanocrystal assembl ed superlattices. The nanocrystals form a new class of materials that have orders in both atomic and nanocrystal length-scales. The nanocrystals are p assivated with organic molecules (called thiolates) that not only protect t hem from coalescence but act as the molecular bonds for forming the superla ttice structure. The interparticle distance is adjustable, possibly resulti ng in tunable electric, optical and transport properties. This paper review s our current progress in nanocrystal self-assembled materials and their th ermodynamic properties probed by in-situ transmission electron microscopy ( TEM). The studies mainly focused on size and shape-controlled nanocrystals to understand the role played by particle shape in determining their physic al and chemical properties. Recent studies on photonic crystals and mesopor ous materials such as silica and titania are also presented. (C) 2000 Elsev ier Science S.A. All rights reserved.