Multilayered heterostructures of Ce0.85Sm0.15O2-delta and Y0.16Zr0.92O2-delta of a high crystallographic quality were fabricated on (001) - oriented MgO single crystal substrates. Keeping the total thickness of the heterostructures constant, the number of ceria-zirconia bilayers was increased while reducing the thickness of each layer. At each interface Ce was found primarily in the reduced, 3+ oxidation state in a layer extending about 2 nm from the interface. Concurrently, the conductivity decreased as the thickness of the layers was reduced suggesting a progressive confinement of the charge transport along the YSZ layers. The comparative analysis of the in-plane electrical characterization suggests that the contribution to the total electrical conductivity of these interfacial regions is negligible. For the smallest layer thickness of 2 nm the doped ceria layers are electrically insulating and the ionic transport only occurs through the zirconia layers. This is explained in terms of a reduced mobility of the oxygen vacancies in the highly reduced ceria.
@article{arxiv.1905.05058,
title = {Interface Effects on the Ionic Conductivity of Doped Ceria / Yttria-stabilized Zirconia Heterostructures},
author = {Daniele Pergolesi and Elisa Gilardi and Emiliana Fabbri and Vladimir Roddatis and George F. Harrington and Thomas Lippert and John A. Kilner and Enrico Traversa},
journal= {arXiv preprint arXiv:1905.05058},
year = {2019}
}