Dislocation dipoles in nanocrystalline films.

A theoretical model is suggested that describes the behavioral features and energetic characteristics of dipoles of grain boundary dislocations in nanocrystalline films. Such dislocation dipoles in nanocrystalline films are shown to play the role of misfit defect configurations that compensate, in part, for misfit stresses that occur due to a mismatch between crystal lattice parameters of films and substrates. Ranges of parameters (misfit parameter, grain size, etc.) are revealed at which the formation of dislocation dipoles is energetically favorable in nanocrystalline films. It is demonstrated that dislocation dipoles are typical structural elements of nanocrystalline films fabricated at highly nonequilibrium conditions.