Interface Diffusion under an Electric Field. Interface Evolution

The evolution of the boundary between two mutually insoluble metallic phases, under the influence of a strong electric field was studied. A perfectly flat interface, y=0, is not affected by an electric field normal to it. However, for any height perturbation of the interface, y=h(x), the electric field has a component along the interface. This creates a diffusion flux of the individual atoms along the interface, which in turn leads to an increase in the amplitude of the initial perturbation and thus to an interfacial profile instability. The process is controlled by interface diffusion in response to three distinct driving forces: the electric field, internal stresses (which arise due to the accumulation or depletion of matter at the interface), and the interfacial curvature. The stress distribution along the interface was found from a self-consistent solution of the elastic problem. For the instability to occur differences in atomic charges or/and in atomic mobilities of the two constituent metals are required. It was shown that small sinusoidal corrugations increase with time for a specified band of wavelengths. The corrugations can grow monotonically or change periodically, depending on their wavelength.