Phase Transitions in Extremely Small Crystals

Abstract
The literature data on the smallest unit cells as well as on the smallest single crystals studied by X-ray diffraction are reviewed. Different types of phase diagrams “temperature—grain size” are presented and discussed. The literature data on the grain-size driven structural phase transitions occurring in nanocrystals (quantum dots) are presented in the form of a database. It was found that there were no reports on phase transitions occurring for nanocrystalline grains with a linear dimension smaller than 7 unit cells. The grain-size driven phase transitions for some nanocrystalline double tungstates, molybdates and phosphates are also described.