Abnormal grain growth of BaTiO3 by 2D nucleation and lateral growth

The microstructure of abnormal grains in BaTiO3 based ceramics suggests that 2D nucleation and lateral growth take place in the material. High-resolution transmission electron microscopy investigation reveals that nucleation takes place at triple junctions of abnormal grain and adjacent matrix grains, subsequently form steps and the steps grow laterally along {1 1 1} planes of the abnormal grains. The abnormal grain boundaries are faceted in the growth direction, however, the ledges, which possess boundaries deviated from low-index crystallographic planes of the abnormal grains, could provide high mobility necessary for abnormal grain growth.