The siliceous intergranular phase in acceptor-doped zirconia and ceria and its effect on the ionic conduction across the grain boundaries were reviewed. Not only the abundant siliceous intergranular liquid phase, but also the monolayer-level siliceous intergranular segregation significantly deteriorates the grain-boundary conduction. To decrease the harmful effect of the resistive siliceous phase at the grain boundary, 'additive scavenging' or 'precursor scavenging' can be employed. The former involves the addition of a secondary phase or another acceptor material with a very high chemical affinity for the siliceous phase, while the latter involves the intergranular phase changing from having a continuous (blocking) configuration to having a discrete (non-blocking) configuration. The mechanisms of various scavenging reactions have been explained, compared, and discussed.
Bibliographical noteFunding Information:
This work was supported by KOSEF NRL program grant funded by the Korean government (MEST) (no. R0A-2008-000-20032-0).
- Charge transfer
- Grain-boundary conduction
- Intergranular phase
ASJC Scopus subject areas