Yttria stabilized zirconia system

Mitterdorfer A., Gauckler L.J., 1999. Identification of the reaction mechanism of the Pt, 02(g) yttria-stabilized zirconia system Part I General framework, modelling, and structural investigation. Solid State Ionics 117(3/4), 187-202. 

A common type of oxygen sensor takes the form of an yttria stabilized zirconia (YSZ, see earlier) tube electroded on the inner and outer surfaces with a porous catalytic platinum electrode. The electrode allows rapid equilibrium to be established between the ambient, the electrode and the tube. Such a system is shown schematically in Fig. 4.36. 

PEVD has been applied to deposit auxiliary phases (Na COj, NaNOj and Na SO ) for solid potenfiometric gaseous oxide (CO, NO, and SO ) sensors, as well as a yttria stabilized zirconia (YSZ) ceramic phase to form composite anodes for solid oxide fuel cells. In both cases, the theoretically ideal interfacial microstructures were realized. The performances of these solid state ionic devices improved significantly. Eurthermore, in order to set the foundation for future PEVD applications, a well-defined PEVD system has been studied both thermodynamically and kinetically, indicating that PEVD shows promise for a wide range of technological applications. 

The heart of this system is an yttria-stabilized zirconia, Zr(Y)0 film, which acts as a solid electrolyte, allowing high conductivity for 0 ions at about 1,000°C. The fuel electrode is a porous Ni/ZrO cermet, which serves both as the electrocatalyst and as the current collector. Actually, electrocalalysis is no longer a problem at such elevated temperatures, and different fuels, including H, regular fossil fuels, and even CO, can be used. The air (oxygen) electrode is a... 

Electrochemical vapor deposition has been explored for making gas-tight, dense, solid electrolyte films on porous substrates, - and the most smdied system has been the yttria-stabilized zirconia films on porous alumina substrates for solid... 

Currently yttria-stabilized zirconia and doped LaGaO, systems seem the most promising materials for developing high temperature (about or higher than 8(X)°C) and intermediate temperature (between 400 and 800°C) electrolysis technologies, respectively [88]. 

For FT SOFCs, perovskite oxides (La,Sr)(Co,Fe)O3 5 have attracted particular attention [50]. Due to chemical reactivity with yttria-stabilized zirconia (YSZ), the use of a protective interlayer between the cathode and electrolyte is required to increase the system s stability during long-term operation [51-53]. 

In order to address both fundamental and application aspects of electrochemical promotion in this Chapter, the combustion of ethylene over Ir02 or RUO2 catalysts and the reduction of NO with propylene over Rh catalysts —all deposited on yttria-stabilized zirconia (YSZ) solid electrolyte— have been chosen as model catalytic systems. While the literature of electrochemical promotion deals mainly with metal catalysts, our laboratory has a long experience with promotion of metal oxide catalysts, such as Ir02 and RUO2. In fact, ethylene combustion with Ir02/YSZ film catalyst was the first catalytic system found to exhibit the phenomenon of permanent electrochemical promotion, which manifests itself as a shift in the steady-state open-circuit activity due to polarization, and is attributed to a change in... 

Trunec has described the thermoplastic extrusion of thin-wall tubes made of yttria-stabilized zirconia and gadolinia-doped ceria [Tru 04], These ceramics are used for solid oxide electrolyte applications, e.g. solid oxide fuel cells. The thermoplastic binder system used consists of ethylene-vinyl acetate copolymer, parafHn wax and stearic acid. With this system tubes with an outer diameter of 10.5 mm and wall thicknesses of 290 and 280 pm could be fabricated. 

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