Size-Dependent Grain-Boundary Structure with Improved Conductive and Mechanical Stabilities in Sub-10-nm Gold Crystals

Low-angle grain boundaries generally exist in the form of dislocation arrays, while high-angle grain boundaries (misorientation angle >15°) exist in the form of structural units in bulk metals. Here, through in situ atomic resolution aberration corrected electron microscopy observations, we report size-dependent grain-boundary structures improving both stabilities of electrical conductivity and mechanical properties in sub-10-nm-sized gold crystals. With the diameter of a nanocrystal decreasing below 10 nm, the high-angle grain boundary in the crystal exists as an array of dislocations. This size effect may be of importance to a new generation of interconnects applications.