A nanocrystal is a crystalline material with dimensions measured in nanometers; a nanoparticle with a structure that is mostly crystalline. These materials are of huge technological interest since many of their electrical and thermodynamic properties show strong size dependence, and can therefore be controlled through careful manufacturing processes. Nanocrystals are also of interest since they often provide single domain crystalline systems that can be studied to provide information that can help explain the behaviour of macroscopic samples of similar materials, without the complicating presence of grain boundaries and other defects.