DCCI, Department of Chemistry and Industrial Chemistry , University of Genova , Via Dodecaneso 31 , 16146 Genova , Italy.
CNR-ICMATE , Via De Marini 6 , 16149 Genova , Italy.
Inorg Chem. 2018 Nov 5;57(21):13047-13062. doi: 10.1021/acs.inorgchem.8b02131. Epub 2018 Oct 5.
Rare-earth (RE)-doped ceria systems, in particular when RE ≡ Nd, Sm, or Gd, are well-known to be characterized by high values of ionic conductivity in the intermediate temperature range, which, in principle, makes them ideal solid electrolytes in solid oxide fuel and electrolysis cells. Defect chemistry turns out to be a pivotal issue in this framework because ionic conductivity is driven by the ability of oxygen vacancies to move through the lattice, and any form of defect clustering tends to depress the efficiency of oxygen transport. In this viewpoint, not only are factors at the average scale assessed, such as the compositional extent of the CeO-like solid solution, but also the occurrence of local inhomogeneities due to vacancy-dopant association is discussed in correlation with its central role in hindering the migration of vacancies. The relationship between the stability of the hybrid phase and the RE ionic size is presented, and the highly complementary role of Raman spectroscopy toward X-ray diffraction is described in detail. The key points of the whole discussion are finally used to identify the most relevant structure-related parameters affecting ionic conductivity in the studied material.
稀土（RE）掺杂的氧化铈体系，特别是当 RE ≡ Nd、Sm 或 Gd 时，以在中温范围内具有高离子电导率为特征，这使得它们在固体氧化物燃料电池和电解池中成为理想的固体电解质。缺陷化学在这一框架中是一个关键问题，因为离子导电性是由氧空位在晶格中移动的能力驱动的，任何形式的缺陷聚集都会降低氧传输的效率。在这种观点下，不仅评估了平均尺度上的因素，如 CeO 类固溶体的组成程度，还讨论了由于空位-掺杂剂缔合而导致的局部不均匀性与其在阻碍空位迁移中的核心作用之间的关系。介绍了混合相的稳定性与 RE 离子尺寸之间的关系，并详细描述了拉曼光谱对 X 射线衍射的高度补充作用。最后，将整个讨论的要点用于确定影响研究材料中离子电导率的最相关的结构相关参数。
