Synthetic Approaches for Quantum-Confined Nanomaterials QCNs

3 Synthetic Approaches for Quantum-Confined Nanomaterials (QCNs) 

The top-down methods are those that reduce the macroscopic particles to the nanosize domains via successive slicing or cutting. This route is not very suitable for preparation of uniform particles of very small sizes. In contrast, bottom-up methods facilitate the formation of small-size and good uniformity particles (usually of different shapes and structures). These routes start from assembling of atoms/molecules during (either in solution or gas phase) to form larger clusters or confined particles. 

Attrition/milling and oxidative cutting are typical top-down methods whereas colloidal synthesis and pyrolytic fusion represent examples of bottom-up approaches. Both approaches play very important roles in the area of nanotechnology and have their own advantages and disadvantages. 

For example, top-down approaches often involve crystallographic damage and surface defects that may significantly affect the optoelectronic properties. However, this approach leads to the bulk production of nano materials therefore, preferred over other routes, provided siu-face imperfections can be suppressed or eliminated. Similarly, bottom-up methods lack the bulk production ability and often require strict control over synthesis conditions to obtain desired properties in reproducible manner. 

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