KINETICS AND GROWTH MODES OF QUASI-2D SILVER BRANCHED ELECTRODEPOSITSPRODUCED IN THE PRESENCE OF A SUPPORTING ELECTROLYTE

Quasi-2d silver electrodeposits were grown electrochemically at consta nt potential from aqueous Ag+ ion-containing solutions in the presence of a supporting electrolyte, at room temperature, using a three-elect rode quasi-2d circular electrochemical cell. Open branching and dense radial branching patterns were distinguished on the centimetre scale, and growth mode transitions could be observed during the process. Bran ching patterns exhibited a mass fractal behaviour with a mass fractal dimension increasing from that expected for a DLA-like pattern to that of a dense branching pattern as either the cathodic overpotential (et a(c)) or the Ag+ ion concentration in the solution (c) was increased. The electrodeposition current increased with time exhibiting different regimes depending on whether an open branching or a dense radial bran ching growth mode prevailed. When the electrodeposition time exceeded a certain critical value, the radial growth rate of electrodeposits (u psilon(r)) approached a upsilon(r) proportional to eta(c) c relationsh ip. The experimental morphologies and growth kinetics were reproduced by Monte Carlo simulations of a growth model in which depositing parti cles follow a biased random walk. (C) 1997 Elsevier Science S.A.