IMPERFECT ORIENTED ATTACHMENT - DISLOCATION GENERATION IN DEFECT-FREENANOCRYSTALS

Dislocations are common defects in solids, yet all crystals begin as d islocation-free nuclei. The mechanisms by which dislocations form duri ng early growth are poorly understood. When nanocrystalline materials grow by oriented attachment at crystallographically specific surfaces and there is a small misorientation at the interface, dislocations res ult. Spiral growth at two or more closely spaced screw dislocations pr ovides a mechanism for generating complex polytypic and polymorphic st ructures. These results are of fundamental importance to understanding crystal growth.