Kinetical faceting of the low index W surfaces under electrical current

It's widely accepted that when the scale goes down deeply into nanometer, the surfaces of materials will play a crucial role. In equilibrium, the as-fabricated surfaces are usually determined by Wulff construction. However, the technique to rebuild the surface in the scale of as fine as 1 nm, especially to build the off-equilibrium high energy facets is still rare. Here we provide a simple but effective solution for rebuilding the surfaces on the basis of kinetics over thermodynamics. Our in situ transmission electron microscopy (TEM) experiments demonstrate that the flat surfaces of W naturally decompose into off-equilibrium faceted surfaces when electrical current passes in certain directions. The experiments and simulations confirmed that, by using a polar plot and the data of surface diffusivities, the stability of any kind of surfaces as well as the exact post-treatment structures (surface type and periodical length) can be determined. This technique can be generally extended to most conductive solid surfaces.