Paul Scherrer Institut , 5232 Villigen-PSI , Switzerland.
Institute of Materials Physics , University of Göttingen , 37077 Göttingen , Germany.
ACS Appl Mater Interfaces. 2018 Apr 25;10(16):14160-14169. doi: 10.1021/acsami.8b01903. Epub 2018 Apr 16.
Multilayered heterostructures of CeSmO and YZrO 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.
高结晶质量的 CeSmO 和 YZrO 多层异质结构被制备在（001）取向的 MgO 单晶体衬底上。保持异质结构的总厚度不变，增加了 CeO2-ZrO2 双层的数量，同时减少了每层的厚度。在每个界面处，Ce 主要以从界面延伸约 2nm 的层中还原的 3+氧化态存在。同时，随着层厚度的减小，电导率降低，表明电荷输运沿 YSZ 层逐渐受到限制。对平面内电特性的比较分析表明，这些界面区域对总电导率的贡献可以忽略不计。对于最小的 2nm 层厚度，掺杂的 CeO2 层是电绝缘的，离子传输仅通过 ZrO2 层发生。这可以用高度还原的 CeO2 中氧空位的迁移率降低来解释。
