Research on the electrochemistry of oxygen ion conductors in the former Soviet Union -: III.: HfO2-, CeO2- and ThO2-based oxides

This review is focused on the analysis of experimental results on oxygen ion-conducting ceramic materials based on HfO2, CeO2, and ThO2, published in the former Soviet Union. In particular, the physicochemical and transport properties of fluorite-related oxides and the characteristics of electronic conduction in these solid electrolytes are briefly reviewed. Emphasis is given to electrocatalytic and electrochemical properties of cerium-containing oxides, which are promising materials for electrodes of electrochemical cells operating in reducing atmospheres, and mixed-conducting membranes. A comparative analysis of specific features of the solid-electrolyte ceramics based on hafnia, zirconia, ceria, and thoria is performed in order to reveal basic tendencies of oxygen ionic transport in fluorite-type oxides, and to identify the potential applicability of these materials in various high-temperature electrochemical devices.