Quasicrystalline gold interface with a hypo-friction property

We have studied a non-symmetric and non-periodic grain boundary in gold. An atomic model is presented and the atomic positions are found to be in agreement with the electron microscopy images. Using the diffraction pattern, we show that the structure is quasicrystalline and related to the irrational number (2) 1/2 . A complete hyperspace periodic description of the interface is given. We use this theoretical view to predict that in the case of an infinite interface of this type, two crystals should glide freely along the incommensurate x -direction whereas they should be blocked along the commensurate z -direction and be adhesive along the third y -direction perpendicular to the boundary. A numerical test confirms this property.