FIvefold twinning in vanosized particles and anocrystalline thin films-ubiquitous metastable structures

摘要

Fivefold twinning in thin films and small paricals of nanometer dimensions is the origin of metastable structures the buiquituous presence of which in a whole calss of nanocrystalline materials results frm the great variety of materials and fabrication processes involved. These are reviewed and discussed together with the formation mechanisms of such structurs and their stability including the role of lattice defects. Various illustrative examples are aimed to emphasise the importance of this phenonmon in the area of nanocrystalline materials.