Appraisal of Ce1−yGdyO2−y/2 electrolytes for IT-SOFC operation at 500°C

Progress in material selection for solid oxide fuel cell technology: A review

Transport properties of solid oxide electrolyte ceramics: a brief review

Within the past 20 years or so, there has occurred an explosion of interest in the magnetic behavior of pyrochlore oxides of the type $A_{2}^{3+}$$B_{2}^{4+}$O$_{7}$ where $A$ is a rare-earth ion and $B$ is usually a transition metal. Both the $A$ and $B$ sites form a network of corner-sharing tetrahedra which is the quintessential framework for a geometrically frustrated magnet. In these systems the natural tendency to form long range ordered ground states in accord with the Third Law is frustrated, resulting in some novel short range ordered alternatives such as spin glasses, spin ices and spin liquids and much new physics. This article attempts to review the myriad of properties found in pyrochlore oxides, mainly from a materials perspective, but with an appropriate theoretical context.

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Magnetic Pyrochlore Oxides

The controllable synthesis of nanostructured CeO2-based materials is an imperative issue for environment- and energy-related applications. In this review, we present the recent technological and theoretical advances related to the CeO2-based nanomaterials, with a focus on the synthesis from one dimensional to mesoporous ceria as well as the properties from defect chemistry to nano-size effects. Seven extensively studied aspects regarding the applications of nanostructured ceria-based materials are selectively surveyed as well. New experimental approaches have been demonstrated with an atomic scale resolution characterization. Density functional theory (DFT) calculations can provide insight into the rational design of highly reactive catalysts and understanding of the interactions between the noble metal and ceria support. Achieving desired morphologies with designed crystal facets and oxygen vacancy clusters in ceria via controlled synthesis process is quite important for highly active catalysts. Finally, remarks on the challenges and perspectives on this exciting field are proposed.

Nanostructured ceria-based materials: synthesis, properties, and applications

The radiation performance of a variety of complex oxides is predicted on the basis of a material's propensity to accommodate lattice point defects. The calculations indicate that a particular class of oxides possessing the fluorite crystal structure should accept radiation-induced defects into their lattices far more readily than a structurally similar class of oxides based on the pyrochlore crystal structure. Preliminary radiation damage experiments substantiate the prediction that fluorites are inherently more radiation resistant than pyrochlores. These results may permit the chemical durability and radiation tolerance of potential hosts for actinides and radioactive wastes to be tailored.

https://science.sciencemag.org/content/sci/289/5480/748.full.pdf

Radiation tolerance of complex oxides

Contour plots of disorder reaction energies across a wide variety of A2B2O7 pyrochlore oxides have been produced, using atomistic simulation calculations based on energy-minimization techniques. The cations studied range from Lu3+ to La3+ on the A site and from Ti4+ to Ce4+ on the B site. The present results relate the experimentally observed stability range of the pyrochlore structure to A and B cation size and disorder. Disorder enthalpies decrease dramatically with increasing B cation size, while the rate of increase with A cation size depends markedly on the particular B cation. The association of anion Frenkel and cation antisite disorders is found to be of importance.

Disorder in Pyrochlore Oxides

Defect cluster formation in M2O3-doped CeO2

Defect cluster formation in M2O3-doped cubic ZrO2

Atomic scale computer simulation based on energy minimization
techniques has been used to study excess oxygen accommodation and migration
in La2NiO4 + δ. The activation
energy for migration in the ac plane is predicted to be 0.29 eV,
while the activation energy outside the ac plane, in the b
direction is predicted to be 2.90 eV. The activation energies within
the ac plane are unaffected by the presence of compensating Ni3+
defects.

Licia Minervini

Papers

Radiation tolerance of complex oxides

Disorder in Pyrochlore Oxides

Defect cluster formation in M2O3-doped CeO2

Defect cluster formation in M2O3-doped cubic ZrO2

Oxygen migration in La2NiO4 + δ