Ceramics, sintered ceria

Figure 3-11. SEM image of the fracture of Sm-doped ceria skeleton used for soaking (a) and net shape prepared ceramics sintered at 1,000°C (b)...

Figure 3-12. The electrical conductivity of Sm-doped ceria ceramics sintered at different...

Mixed ion and electronic conducting ceramic membranes (e.g. yttria-stabilized zirconia doped with titania or ceria) can be slip cast into a tubular form from the pastes containing the constituent oxides in an appropriate proportion and other ingredients and the cast tubes are then subject to sintering at 1,200 to 1,500X to render them gas impervious [Hazbun, 1988]. 

In addition to the dilution effect described above, the surface area of the oxygen-storage material also figures into a potentially more serious deactivation mode, loss of noble metal by deep encapsulation [19,20], As ceria-zirconia sinters, some of the noble metal particles supported on it may become trapped, either within single grains or at grain boundaries of the dense ceramic, as shown by the TEM micrograph in Fig. 10.9 [20]. 

Sheldon W. Brian, Nicholas D. Jason, and Mandowara Sunil. Tensile stress evolution during the early-stage constrained sintering of gadolinium-doped ceria films. J. Am. Ceram. Soc. 94 no. 1 (2011) 110-117. 

Ceria has been used as the ceramic part (or as an addition) in nickel- or ruthenium-cermet anodes for hydrogen oxidation. " Beneficial effects have been reported and interpreted as most likely being due to the broadening of the three-phase boundary zone. However, one of the major drawbacks of using ceria in cells with YSZ-based electrolytes is its chemical reactivity with the YSZ electrolyte at high temperatures. Sintering of a doped ceria anode on a YSZ electrolyte at high temperatures (>1200°C) results in the formation of a reaction (diffusion) zone with limited oxide ion conductivity. ... 

Among trivalent rare earth metals, gadolinium is also known to make a solid solution with ceria to increase its ionic conductivity. Catalytic activity of the anode, on the other hand, can be further improved by embedding highly dispersed nickel particles in the ceramic matrix [15] this should improve the long-term stability of the anode through delayed sintering of nickel particles. 

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