Abstract:
Morphological instability has been studied experimentally in the growth
from dilute Ba(NO3)(2) aqueous
solution of crystal films with free surfaces. The observation of transitions
from faceted crystal to dendrite, and
then to fractal-like patterns is presented. The micro-morphologies
of these patterns are investigated. It is
suggested that the competition between the step movement and the solute
transfer in the growth of thin films
determines the stability of the faceted crystal corners. The fractal-like
pattern is attributed to random
successive nucleation, which is induced by the decrease of the nucleation
barrier at high supersaturation and
the disturbance caused by the competition between surface-tension-gradient
and wetting effects.