ATOMIC-STRUCTURE OF GRAIN-BOUNDARIES

Atomic-scale structures of fee oxide and metal grain boundaries are investigated by high-resolution electron microscopy. This paper focuses on the examination of structures that evolve when the grain boundary deviates from the ideal planar and periodic geometry. Examples are given for atomic-scale grain boundary steps with and without dislocation character. The misorientation dependence of atomic-scale grain boundary structures is investigated in (1 $($) over bar$$ 10) tilt grain boundaries of gold near the (113)(113) low-energy cusp. Common grain boundary relaxation modes include those of slacking disorder, low-index asymmetric facets and microfacets. All of the observed structures and atomic relaxation modes in grain boundaries are consistent with the short-range nature of the interatomic interactions which lead to misfit localization and a tendency to preserve as much as possible the atomic coordination of the defect-free solid.