Ceria based ceramics

Zhang, T.S. et al.. Aging behaviour and ionic conductivity of ceria-based ceramics A comparative study. Solid State Ionics 170 (2004) 209-217. 

The present applications of ceria-based ceramics impose strict requirements on the quality and purity of the powders used. Several studies have described the synthesis of ceria nanopowders of high quality and with a well-defined morphology. Typical methods of preparation include hydrothermal synthesis [263, 264], the hydrolysis of an alkoxide solution (sol-gel) ]265], chemical precipitation [266], mechanochemical processing ]267], and gas-phase reaction ]268]. Emulsion techniques can also be used, as these reduce not only the production costs of high-purity spherical powders but also the degree of aggregation. Thus, ceria powders with an average particle size <20 nm and a narrow particle size distribution can be... 

The applications of ceria based materials are related to a potential redox chemistry involving Cerium(III) and Cerium(lV), high affinity of the element for oxygen and sulfur, and absorption / excitation energy bands associated with its electronic structure. Important areas for application of cerium based materials are catalysis and chemicals, glass and ceramics, phosphors and metallurgy. 

Tru04] Trunec M (2004) Fabrication of zirconia- and ceria-based thin wall tubes by thermoplastic extrusion. J Eur Ceram Soc vol 24 No 4 pp 645-651... 

Despite these recent results, the low electronic conductivity of ceria-based oxides makes it difficult to use them as a single-material fuel electrode at lower temperatures. The surface reaction kinetics and lateral electron transport or rate of removal of electrons from the ceria surface have been reported to be the most likely rate-limiting processes. At temperatures below 1000 °C ceria-based oxides only show promising performance as a component of cermets with Ni or other ceramic electrode materials, or as will be illustrated later, when infiltrated as a nano-sized phase in porous electronic conducting backbones. 

One very promising solution to overcome these drawbacks with ceramic materials as fuel electrodes is the infiltration of nanoparticles of ceria-based materials into the porous structures of the fabricated ceramic backbones. The infiltration of various materials has recently been used in SOFC electrodes (see e.g. the works ° and references therein for inspiration). Infiltration into composite fuel electrode backbones is illustrated in Fig. 12.22. 

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