Nanometals

Nanotechnology, nanoscience, nanostructures, nanoparticles… These are now some of the most widely used terms in materials science literature.But why are nanoscale materials and processes so attractive?From the point of view of the general public, nanotechnology appears to be the fabrication of miniature machines, which will be able to travel through the human body and repair damaged tissues, or supercomputers small enough to fit in a shirt pocket.However, nanostructured materials have potential applications in many more areas, such as biological detection, controlled drug delivery, low-threshold lasers, optical filters, and sensors, among others.In fact, it is relatively easy to find examples of the use of metal nanoparticles (maybe not deliberately) as decorative pigments since the time of the Romans, such as those contained in the glass of the famous Lycurgus Cup (4 th century AD).The cup can still be seen at the British Museum 1 and possesses the unique feature of changing color depending upon the light in which it is viewed.It appears green when viewed in reflected light, but looks red when a light is shone from inside and is transmitted through the glass.Analysis of the glass reveals that it contains a very small amount of tiny (~70 nm) metal crystals containing Ag and Au in an approximate molar ratio of 14:1.It is the presence of these nanocrystals that gives the Lycurgus Cup its special color display.It was not until 1857, however, that Michael Faraday reported a systematic study of the synthesis and colors of by