Influence of magnetic field and gravity on the morphology of zinc fractal electrodeposits

We present a comprehensive study of growth of zinc fractal electrodeposits in a flat electrochemical cell considering the effects of applied voltage, electrode shape and thickness, ion concentration and applied magnetic field for both concentric and parallel electrode geometries. The effect of gravity is also considered in vertical cells. ‘Phase diagrams’ set out the variety of morphologies achievable at different voltages and concentrations for both electrode geometries. Electron microscope analysis indicates that the deposits are built from individual micron-sized crystallites. The system is modelled numerically using a number of modifications to the diffusion-limited aggregation (DLA) model to introduce migration and convection. Experimentally observed morphologies are reproduced numerically for horizontal and vertical, concentric and parallel electrode cells. Each occupied numerical site represents not an individual atom, but the point of nucleation and growth of an individual zinc crystallite containing ∼10¹⁰ atoms.