Morphological instability of crystals grown from thin aqueous solution films with a free surface

Abstract

Morphological instability has been studied experimentally in the growth from dilute Ba(NO₃)₂aqueous 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 comers. 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.