Host: The Ceramic Society of Japan
Segregated dopants at grain boundary dramatically change the mechanical and electrical properties in materials. The knowledge of the behavior of these dopants is therefore a key for further material developments. Here, a Zr doped alumina (Al2O3) bicrystal was fabricated and the atomic structure of the grain boundary was characterized using scanning transmission electron microscopy (STEM). Zr was found to segregate to specific sites along the grain boundary, which were neighbored by Al columns of weak image intensity. First principles calculations and static lattice calculations revealed that the charge compensating Al vacancies are most stable in Al columns neighboring the location of the Zr sites. Multi-slice simulations of STEM images confirmed that Al columns containing vacancies exhibit a reduction in image intensity. These results give strong evidence that the associated Al vacancies are strongly influenced by the atomic site of Zr segregation.
