posted on 2024-01-11, 19:19authored byBingqian Song, Heung-Sik Park, Jeonghun Suh, Jeongdae Seo, Jihun Kim, Chan-Ho Yang
Ionic
movement has received renewed attention in recent years,
particularly in the field of ferroelectric oxides, since it is intrinsically
linked to chemical reaction kinetics and ferroelectric phase stability.
The associated surface electrochemical processes coupled local ionic
transport with an applied electric bias, exhibiting very high ionic
mobility at room temperature based on a simple electrostatics scenario.
However, few studies have focused on the applied-polarity dependence
of ionic migration with directly visualized maps. Here, we use incorporated
experiments of conductive scanning probe microscopy and time-of-flight
secondary ion mass spectrometry to investigate oxygen ionic migration
and cation redistribution in ionic oxides. The local concentrations
of oxygen vacancies and other cation species are visualized by three-dimensional
mappings, indicating that oxygen vacancies tend to be ejected toward
the surface. An accumulation of oxygen vacancies and ionic redistribution
strongly depend on tip polarity, thus corroborating their role in
the electrochemical process. This work illustrates the interplay between
ionic kinetics and electric switching.