Atomic-Scale Observation of Titanium-Ion Shifts in Barium Titanate Nanoparticles: Implications for Ferroelectric Applications

Ferroelectric nanoparticles (NPs) have attracted considerable attention owing to their size effect on the ferroelectricity and their possible application toward future electronic devices such as multilayer ceramic capacitors and ferroelectric random access memory. The ferroelectricity disappears for NPs smaller than the critical size, which has been an obstacle for the development of materials. Although the fundamental mechanisms of the size effect should be clarified to overcome this problem, the understanding has been made ambiguous by the fact that NPs of different morphologies prepared by different methods exhibit various critical sizes, which indicates that more investigations should be conducted on the appearance/disappearance of ferroelectricity in NPs. To gain insight into the appearance of ferroelectricity, atomic-scale characterizations are beneficial because the ferroelectricity is closely related to the atomistic structures. In the present study, atomic-scale scanning transmission electron mic...