Screw
Dislocations on Polycenes: A Requirement for Crystallization
H. M. Cuppen, W. S. Graswinckel, and H. Meekes
Crystal Growth & Design, 4 (6) 2004, 1351 -1357
Abstract:
The morphology and growth behavior of naphthalene, anthracene, and
tetracene is studied both experimentally and by computer simulations.
We will show that the attachment energy morphology prediction for all
compounds gives approximately the correct habit, but that this is
merely coincidental. Our Monte Carlo simulations and vapor growth
experiments show that the thickness growth of the crystals
perpendicular to the {001} faces is due to spirals on that face. If
these screw dislocations were not present, the basal faces would not
grow and no crystal would be formed at moderate driving force. At very
high driving forces, very thin plates without screw dislocations were
observed, with a morphology that is in agreement with the results of
our Monte Carlo simulations.