Nanotechnology, the field of research and technology which entail development of materials in nanoscale (i.e. with dimension in the order of one billionth of a meter) is changing our daily life and provides new products and tools which could hardly be imagined few decades ago. One of the prominent example of the nanotechnology routed product is the nano-chip which has not only squeezed the size of the computer but also improves their performance considerably. Materials science is one of the major field of research in which the fabrication and characterization of nano-materials are performed. There are many methods for fabrication of nanoscale materials and structures such as nano-lithography and chemical synthesis which have their own pros and cones (it will be discussed in future posts). Nanoparticles are one of the extensively developed and studied nano-material and found applications in optics, electronics, cancer therapy, magnetism and chemistry amongst others.
One of the simplest and cheapest method for fabrication of nanoparticles is dewetting. It is indeed based on the simple heating of a metal (or generally solid) film that ultimately transform the continuous film to separated clusters. This happened because the thin metal films are metastable and transform to agglomerated particles upon heating in order to reduce the total energy of the surfaces (e.g. metal, substrate and the interface of the metal and substrate). The shape and size of the resulting nanoparticles upon heating can be manipulated by control of the thickness of the initial film, temperature of the process and the morphology of the substrate. The latter can be useful to rather precisely arrange the particles over the surface for the desire application. The following sketch shows the process in very simple way.