Dislocation density in pure crystals grown from melts

Abstract Physical reasons are considered which are responsible for dislocation formation in crystals grown by different ways, i. e. by Czochralski's, Stepanov's, Kyropoulos's, Verneuil's, Bridgman's, Stockbarger's methods and floating zone technique. Equations are presented allowing to evaluate the dislocation density in pure crystals prior to testing. The conditions for obtaining dislocation free crystals have been considered. The equations for dislocation density evalution have been compared with the experimental results of different authors. Thermal stresses have been proved to be the main source of dislocation formation, and the equations corresponding to this mechanism in most cases enable to predict the dislocation density with the error being a factor of 1–3.