Fractal structures in two-metal electrodeposition systems I: Pb and Zn.
Pattern formation in two-metal electrochemical deposition has been scarcely explored in the chemical literature. In this paper, we report new experiments on zinc-lead fractal co-deposition. Electrodeposits are grown in special cells at a fixed large value of the zinc ion concentration, while that of the lead ion is increased gradually. A very wide diversity of morphologies are obtained and classified. Most of the deposited domains are almost exclusively Pb or Zn. But certain regions originating at the base cathode, ranging from a short grass alley to dense, grown-up bushes or shrubs, manifest a combined Pb-Zn composition. Composition is determined using scanning electron microscopy/energy dispersive x ray measurements as well atomic absorption spectroscopy. Pb domains are characterized by shiny leaf-like and dense deposits as well as flowers with round, balloon-like corollas. The Zn zones display a greater variety of morphologies such as thick trunks and thin and fine branching, in addition to minute "cigar flower" structures. The various morphologies are analyzed and classified from the viewpoint of fractal nature, characterized by the box-count fractal dimension. Finally, macroscopic spatial alternation between two different characteristic morphologies is observed under certain conditions.
Department of Chemistry, American University of Beirut, P. O. Box 11-0236, Riad El Solh, 1107 2020 Beirut, Lebanon.
Elias
E
Nakouzi
Rabih
R
Sultan
D003198:Computer Simulation; D004595:Electroplating / Q000379:methods*; D017709:Fractals; D007854:Lead / Q000032:analysis / Q000737:chemistry*; D008956:Models, Chemical; D015032:Zinc / Q000032:analysis / Q000737:chemistry*
D007854:Lead; D015032:Zinc