Local atomic structure of a near-sigma 5 tilt grain boundary in MgO

Clear understanding of the structure-property relation in polycrystalline materials requires atomic-resolution imaging of grain boundary (GB) structures especially for the GBs with misalignments. In this study, we apply a bicrystal technique to fabricate the Σ5 and near-Σ5 GBs of MgO with tunable bonding angle and demonstrate that the misalignments in GBs could be compensated by a periodic displacement shift complete dislocation array. The atomic-resolution images reveal that the near-Σ5 GB is composed of an array of normal Σ5 GB structural units intercalated by deformed Σ17 GB units. The atomic-scale characterization presented is applicable to other GB species in a range of polycrystalline materials.