A DENDRITE MODEL OF CURRENT INSTABILITY IN RBAG4I5

A theoretical model of the electronic current instability observed exp erimentally by Bredikhin et al. in the cell Ag(-)/RbAg4I5/C(+) at vari ous constant voltages is proposed. The model is based on the concept o f fractal growth of silver dendritic clusters from the Ag(-)/RbAg4I5 i nterface. It is shown that some of the clusters make connections betwe en opposite electrodes at sufficiently large voltages, which leads to stochastic current oscillations. We show that the number of connecting clusters increases as the voltage is raised and therefore current osc illations become more frequent. All experimental dependences on curren t instability are well described within the framework of a mean-field approach to the theory of reversible diffusion-limited aggregation wit hout branching.