We observe the spontaneous reemergence of long-range crystalline order in the electrochemical deposition of metal dendrites very far from equilibrium. This long-range order appears simultaneously with novel superlattice structures as revealed by high-resolution x-ray and electron diffraction. In order to explain these observations, we propose a simple picture, which we call the ‘‘keystone model,’’ for electrocrystallization in an aqueous environment.

• Received 18 September 1989

DOI:https://doi.org/10.1103/PhysRevLett.64.2152