Grain-boundary structural transition and sintering behavior in barium titanate

Structural transition of grain boundaries, between rough and faceted, was induced by changing oxygen partial pressure and its effect on grain growth and densification has been studied in BaTiO3. When the boundaries were rough, grain growth and densification occurred continuously with sintering time. For faceted boundaries, however, abnormal grain growth occurred or grain growth almost stopped below or above a critical size of initial grains, respectively, Densification was also almost stopped when the boundaries were faceted. These experimental results demonstrate that the grain boundary structural transition critically affects the densification and grain growth in polycrystals.