Abstract
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The ultimate frontier in nanomaterials engineering is to realize their composition control with atomic scale precision to enable fabrication of nanoparticles with desirable size, shape
and surface properties. Such control becomes even more useful when growing hybrid
nanocrystals designed to integrate multiple functionalities. Here we report achieving such
degree of control in a family of rare-earth-doped nanomaterials. We experimentally verify the
co-existence and different roles of oleate anions (OA-) and molecules (OAH) in the crystal
formation. We identify that the control over the ratio of OA- to OAH can be used to
directionally inhibit, promote or etch the crystallographic facets of the nanoparticles.
This control enables selective grafting of shells with complex morphologies grown over
nanocrystal cores, thus allowing the fabrication of a diverse library of monodisperse
sub-50 nm nanoparticles. With such programmable additive and subtractive engineering a
variety of three-dimensional shapes can be implemented using a bottom–up scalable
approach.