0000000000292312
AUTHOR
Klaus-dieter Kreuer
Dopants and defects: local structure and dynamics in barium cerates and zirconates
In this paper we present an overview of state-of-the-art EXAFS measurements and data analysis on Ba, Ce, Zr, Y, In and Gd local environments in Y:BaCeO3, In:BaCeO3, Gd:BaCeO3, Y:BaZrO3, and In:BaZrO3, at different temperatures, hydration degrees and doping levels. This approach allows to reach unprecedented insights on the peculiar role of the dopant, and its interactions with the other lattice defects. In particular, we evidence that each different dopant shows unique behavior, depending mainly on its electronic structure, and that the usual criterion of ionic radius matching is not useful to outline an effective doping strategy of proton-conducting perovskites. As what concerns the struct…
Proton Dynamics in In:BaZrO3: Insights on the Atomic and Electronic Structure from X-ray Absorption Spectroscopy
The local structure of Ba2+, Zr4+, and In3+ in In:BaZrO3 is investigated with EXAFS for samples having 0 to 75% In3+ content. It is found that indium can be inserted in any ratio in the host matrix oxide and that the oxygen coordination shell displays an In-O distance very similar to the Zr-O length. In the Zr-rich compositions, there is a preferred dopant-vacancy association that, however, does not give rise to dopant-proton interaction in the hydrated samples. The tendency of Ba2+ to be attracted toward the dopant site is attributed to the electrostatic interaction with the dopant and to the structural rearrangement around the In3+ site. Third cumulant analysis at high temperatures (up to…