Correlations between structure, microstructure and ionic conductivity in (Gd,Sm)-doped ceria.

The structural, microstructural, Raman and ionic conductivity properties of (Gd,Sm)-doped ceria were studied and compared to the ones of similar ceria systems with the aim of deepening the comprehension of the correlations between defect chemistry and movement of oxygen vacancies in such materials, which are ideal candidates as electrolytes in solid oxide cells. The system was chosen as it combines the advantages of using the most effective doping ions for ceria, namely Sm and Gd, and the expected positive effects of multiple doping. The main effect of double doping on the structure is the enlargement of the compositional region where ionic conductivity takes place, due to the entrance of the smaller doping ions into defect clusters, mainly trimers and dimers (RE ≡ rare earth).

Evaluation of the Defect Cluster Content in Singly and Doubly Doped Ceria through In Situ High-Pressure X-ray Diffraction.

Defect aggregates in doped ceria play a crucial role in blocking the movement of oxygen vacancies and hence in reducing ionic conductivity. Nevertheless, evaluation of their amount and the correlation between domain size and transport properties is still an open issue. Data derived from a high-pressure X-ray diffraction investigation performed on the Ce(NdTm)O system are employed to develop a novel approach aimed at evaluating the defect aggregate content; the results are critically discussed in comparison to the ones previously obtained from Sm- and Lu-doped ceria.

Ionic conductivity and local structural features in CeSmO.

Sm-Doped ceria is one of the most promising materials to be used as electrolyte in solid oxide fuel cells due to its remarkable ionic conductivity values in the intermediate temperature range. Transport properties and local structural features of Ce1-xSmxO2-x/2 (0.1 ≤ x ≤ 0.

From nano to microcrystals: effects of different synthetic pathways on the defect architecture in heavily Gd-doped ceria.

The evolution of the defect structure and microstructure of heavily Gd-doped ceria (CeREO, 0.313 ≤ μ ≤ 0.438) for different synthetic pathways is investigated here to explore the way defects interact with each other in a composition range known to effectively hamper the application of the material as an electrolyte.

Lu-, Sm-, and Gd-Doped Ceria: A Comparative Approach to Their Structural Properties.

A room temperature structural study has been performed through the whole compositional range of the (CeLu)O system by synchrotron X-ray diffraction and μ-Raman spectroscopy. Samples were synthesized by thermal treatment in air at 1373 K of coprecipitated mixed oxalates. A CeO-based solid solution with a fluorite-type structure (F) was found to be stable up to x = 0.