About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
|
Grain Boundaries, Interfaces, and Surfaces: Fundamental Structure-Property-Performance Relationships
|
| Presentation Title |
The Influence of Electric Fields and Charge-Compensating Defects on Grain Growth in Alumina |
| Author(s) |
Asaf Kazmirsky, Xinnian Wu, Iman Naamne, Rachel Marder, Yaron kauffmann, Yuanshen Qi, Wayne D. Kaplan |
| On-Site Speaker (Planned) |
Wayne D. Kaplan |
| Abstract Scope |
The enhancement of densification under applied electric fields has increased interest in field-assisted sintering, but how such fields affect grain growth remains unclear. In this study, model experiments were used to examine the influence of an external electric field (300 V/cm) on grain growth in dense, polycrystalline undoped and Ca-doped alumina at 1600°C. In Ca-doped alumina annealed without an electric field, Ca increases grain boundary mobility, especially for boundaries parallel to the rhombohedral plane, producing elongated grains. Under an applied field, however, Ca accumulated near the positive electrode, where the grain boundary mobility decreased. These results indicate that Ca itself reduces grain boundary mobility in alumina, whereas oxygen vacancies, which act as charge-compensating defects when Ca dissolves in alumina, are responsible for the enhanced grain growth kinetics. Comparisons with Fe-doped alumina, where segregating Fe2+ increases mobility while segregating Fe3+ decreases mobility, support these conclusions. |