Perovskite-related Oxides

The spinel family of oxides with composition AB2O4 has the A and B cations distributed in octahedral and tetrahedral sites in a close-packed oxygen structure (Supplementary Material SI). Impurity doping can take place by the addition of a dopant to octahedral or tetrahedral sites. In this, the spinel family of compounds is quite different from the A2B04 perovskite-related phases of the previous section in that both cation sites are similar in size and can take the same cations. 

In this chapter the technological development in cathode materials, particularly the advances being made in the material s composition, fabrication, microstructure optimization, electrocatalytic activity, and stability of perovskite-based cathodes will be reviewed. The emphasis will be on the defect structure, conductivity, thermal expansion coefficient, and electrocatalytic activity of the extensively studied man-ganite-, cobaltite-, and ferrite-based perovskites. Alterative mixed ionic and electronic conducting perovskite-related oxides are discussed in relation to their potential application as cathodes for ITSOFCs. The interfacial reaction and compatibility of the perovskite-based cathode materials with electrolyte and metallic interconnect is also examined. Finally the degradation and performance stability of cathodes under SOFC operating conditions are described. 

Kharton W, Yaremchenko AA, and Naumovich EN. Research on the electrochemistry of oxygen ion conductors in the former Soviet Union. B. Perovskite-related oxides. J. Sol. St. Electrochem. 1999 3 303-326. 

The perovskite structure is capable of high anion conductivity when oxide vacancies are introduced, as in, for example, Lai (Sr Co03 (/2 or in the perovskite-related superconductor phases, La2Cu04 and YBa2Cu307. The oxide ion transport number is not unity since such materials are often electronic conductors as well, due to the presence of... 

Wang, J Yasuda, H Imnnaru, K Misono M. Catalytic decomposition of dinitrogen oxide over perovskite-related mixed oxides, Bull. Chem. Soc. Japan, 1995, Volume 68, Issue 4, 1226-1231. 

Fig. 16.2 Idealized structures of some perovskite-related layered oxides and their fluoride relatives.2)...

Table 16.3 Perovskite-Related Layered Oxides Studied for Photocatalysis... 

Superstructures, Ordered Defects Nonstoichiometry in Metal Oxides of Perovskite Related Structuresf... 

A third series of perovskite related intergrowths has a general formula A B 03 +2, where A is a large cation, and B a medium sized cation, typified by the (Na,Ca) Nb 03 +2 series. The oxides are intergrowths of slabs of perovskite stracture with the halite structure. They differ from the Ruddleston-Popper series in that the (idealized) perovskite slabs are sliced along 110 rather than 100. ... 

Perovskite related oxides WO3, ReOs, V6O13 Tunnel structures... 

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