Nanomaterials — Structure, morphology and stability

Manufactured nanomaterials can be synthesized in two ways. The bottom-up approach involves building nanomaterials by assembling atoms, molecules or aggregates. It is generally based on growth methods. The "top-down" approach is based on miniaturizing a material by fractioning or removing material, and is generally based on microelectronics methods. In all cases, the materials obtained are not necessarily stable. Nanoparticles may have exotic crystallographic structures, specific morphologies, non-standard thermodynamic phases, or be influenced in shape and size by the substrate on which they are deposited, or by neighboring particles. This is also the case for thin films, whether free or deposited on a substrate, which can exhibit morphological instabilities linked to their thermodynamic, mechanical and elastic properties, or to their coupling. Two-dimensional materials, which can be described as films of atomic or molecular thickness, also have specific stability characteristics. Finally, it is possible to obtain nano-objects in the form of hollow nanoparticles, nanowires or nanotubes with high stability.

Understanding the structure, morphology and stability conditions of nanomaterials is a prerequisite for integrating them into any laboratory device or industrial process. This is the subject of this article.