Linear stability analysis of unsteady galvanostatic electrodeposition in the two-dimensional diffusion-limited regime

The nature and origin of the morphological instability which occurs in confined and unsupported electrodeposition experiments in galvanostatic regimes is discussed in terms of linear stability analysis, based on a theoretical work of Sundstrom and Bark.(1) The originality of our approach rests on the comparison of two-dimensional experimental concentration maps obtained by phase-shift interferometry with numerical simulations of the nonstationary evolution equations. We demonstrate both experimentally and theoretically that a morphological transition occurs when the concentration of reducible species approaches zero. We point out the relevance of the electroneutrality hypothesis for predicting the interfacial instability with reference to a destabilization mechanism, based on the existence of a space charge, proposed by Chazalviel.(2)