Dendritic and Fractal Patterns in Electrolytic Metal Deposits

Pattern formation in the electrodeposition of Zn from a thin layer of ZnSO₄ solution was studied as a function of electrolyte concentration and applied voltage. We found several qualitatively different growth forms in this system. Most strikingly, a transition from dendritic crystals (where crystalline anisotropy dominates) to disordered ramified patterns is found when the electrolyte concentration is reduced. The disordered patterns may be described as fractal below a concentration-dependent cutoff length.