The morphology of iron electrodeposit is shown to relate closely to the pH of the electrolyte solution. Macroscopically, depending on the strength of the interbranch convection, which is associated with the concentration of H3O1 in the electrolyte, the deposit morphology varies from treelike pattern to meshlike pattern and dense-branching morphology. Microscopically the deposit is ramified and dense-branching at lower concentration of H3O1, while it becomes relatively smooth and stringy at higher H3O1 concentration. The symmetry of the convective vortices on the two sides of the growing tip is observed to decide the growth behavior of the tip. We suggest that H3O1 influences the pattern formation and pattern selection in the electrodeposition of iron from FeSO4 solution by either initiating interbranch convection or changing the effective interfacial energy of the deposit and the electrolyte.

A consecutive rotation of crystallographic orientation has been observed in lateral crystallization of NH4Cl on a glass substrate, which induces a periodic distribution of faceted and roughened regions on the surface of a crystallite aggregate. Experimental observation indicates that this phenomenon derives from the asymmetric surface energies at the growth front, which deform the nascent nucleus and tilt the crystallographic orientation in the nucleation-mediated layered growth. We suggest that this effect is significant for a class of lateral growth where nucleation plays a dominate role.

We report here the electrodeposition of copper on an insulating glass substrate without introducing additives into the electrolyte and/or metallic clusters on the surface of the substrate. The deposit morphology, which varies from compact film to dense-branching patterns,can be achieved by changing the concentration and pHof the electrolyte, and the electric current in electrodeposition. The grain size of the electrodeposits is analysed for various growth conditions. We find that finer copper grains can be easily achieved at large electric current, high pH and low electrolyte concentration. We explain, using the theory of nucleation, why a metallic layer may develop horizontally over an insulating glass plate.

In situ observations using interference contrast microscopy have carried out in an electrochemical deposition system of a ZnSO4 solution film. Concentration oscillation around a growing dendrite tip, which is illustrated by local contrast oscillation, has been found to correspond to sidebranching of the dendrite. A model concerning the competition between diffusion of cations and growth of dendrites has been used to explain this oscillation phenomenon. It appears that this concentration field oscillation in front of the dendrite tip plays an important role in sidebranching.