عنوان

Ultrafast collective oxygen-vacancy flow in Ca-doped BiFeO3

Number

LA68s7648b

Title Proper

Ultrafast collective oxygen-vacancy flow in Ca-doped BiFeO3

General Material Designation

[Article]

First Statement of Responsibility

Lim, JSLee, JHPark, HSGao, RKoo, TYMartin, LWRamesh, RYang, CH

Text of Note

© 2018, The Author(s). The ultrafast motion of oxygen vacancies in solids is crucial for various future applications, such as oxide electrolytes. Visualization and quantification can offer unforeseen opportunities to probe the collective dynamics of defects in crystalline solids, but little research has been conducted on oxygen vacancy electromigration using these approaches. Here, we visualize electric-field-induced creation and propagation of oxygen-vacancy-rich and -poor competing phases and their interface with optical contrast in Ca-substituted BiFeO3 that contains a high density of mobile oxygen vacancies. We quantitatively determined the drift velocity of collective migration to be on the order of 100 μm s−1 with an activation barrier of 0.79 eV, indicating a significantly large ionic mobility of 2 × 10−6 cm2 s−1 V−1 at a remarkably low temperature of 390 °C. In addition, visualization enables direct observation of fluidic behavior, such as the enhancement of conduction at channel edges, which results in U-shaped viscous propagation of the phase boundary and turbulence under a reverse electric field. All of these results provide new insights into the collective motion of defects.

Date of Publication

2018

Title

UC Berkeley

Electronic name

[Article]

276956

a

Y