Proton-conducting perovskites

Haile, S. M., Staneff, G., and Ryu, K. H. Non-stoichiometry, Grain Boundary Transport and Chemical Stability of Proton Conducting Perovskites, Journal of Materials Science, 36, 1149 (2001). 

In Chapter 10, the use of membranes for different applications are described. One of the possible membranes for hydrogen cleaning is an asymmetric membrane comprised of the dense end of a proton conduction perovskite such as BaCe0 95 Yb0 05O3 5 and a porous end to bring mechanical stability to the membrane. In this case, it is possible to take from the slurry, obtained by the acetate procedure, several drops to be released over a porous ceramic membrane, located in the spinning bar of a spin-coating machine. Thereafter, the assembly powder, thin film porous membrane is heated from room temperature up to 1573 K at a rate of 2K/min, kept at this temperature for 12 h, and then cooled at the same rate in order to get the perovskite end film over the porous membrane [50],... 

Absorption and Diffusion of Hydrogen in Nanocrystals of the BaCe095Yb0 05O3 8 Proton-Conducting Perovskite... 

Hydrogen-permselective silica membranes [8,10] can be, as well, synthesized by a particular application of solgel techniques [142,143], Additionally, hydrogen permselective asymmetric membranes composed of a dense ceramic of a proton-conducting perovskite over a porous support have been developed [40], However, some difficulties with respect to their stability is possible in certain reactive environments [121],... 

Development of compact fuel cells, created by combining proton conductive perovskite-type oxide ceramics with metal-hydride materials, has been already proposed [1], Our group expects that the compact fuel cells can be utilized under radiation environments such as fission and fusion reactors or cosmic [2], Therefore, it is very important to understand behaviors of electron and proton conductions under radiation environments. 

Applications of Proton Conducting Perovskites, Rangachary Mukundan, Eric L. Brosha, and Fernando H. Garzon, A symposium in Honor of the 65th Birthday of Professor Wayne L. Worrell, PV 2002-5, pp. 142-147 (2002) The Electrochemical Society Inc. 

One category of dense proton conducting membranes that has received considerable attention in the preceding decade is proton conducting perovskite type oxide ceramics [4-6]. The stoichiometric chemical composition of perovskites is represented as ABO3, where A is a divalent ion (A +) such as calcium, magnesium, barium or strontium and B is a tetravalent ion (B +) such as cerium or zirconium. Although simple perovskites such as barium cerate (BaCeOs) and strontium cerate... 

Composite membranes also employ dense cermets fabricated by sintering together mixed powders of metal and ceramic [10-12], Examples include powders of Pd and its alloys sintered with powders of perovskites [11,12], niobium sintered together with AI2O3 [12], and nickel sintered with proton-conducting perovskites. Layers of dense cermets, 25-100 xm thick, are supported by porous ceramic tubes. Cermets employing chemically reactive metals, Nb, Ta, U, V, Zr, and their alloys, are typically coated with Pd and alloys thereof [11,12],... 

Proton conducting perovskite oxides are the subject of numerous current studies, as these materials have a potential use in a number of electrochemical applications, including fuel cells, electrochromic displays and hydrogen sensors. Perovskite... 

The hydration process in all proton conducting perovskites can be formally written as a defect equation ... 

In this chapter, the distinctive features of proton conductors as an electrolyte for use in a fuel cell or in a steam electrolyser are discussed in comparison to those of oxide ion conductors. In addition, the possibility of using a proton conductor in a hydrogen gas separator is also described. As examples, the experiments on fuel-cells, steam electrolysers and hydrogen gas separators using proton conducting, perovskite-type oxides are described. 

Matsumoto, H., Shimura, T., Iwahara, H., Higuchi, T., Yashiro, K., Kaimai, A., et al. (2006). Hydrogen separation using proton-conducting perovskites. Journal of Alloys and Compounds, 408, 456—462. 

Figure 18.6 Comparison of conductivities of typical proton-conducting perovskite oxides in a hydrogen atmosphere (Iwahara, 1995).

Kreuer, K. D., MOnch, W., Ise, M., Fuchs, A., Traub, U., and Maier, J. (1997). Defect interactions in proton conducting perovskite-type oxides. Ber. Bunsenges. Phys. Chem 101 1344-1330. 

S. Yamaguchia, K. Nakamuraa, T. Higuchib, S. Shine, and Y. Iguchia, Basicity and Hydroxyl Capacity of Proton-conducting Perovskites, Solid State Ionics, 136-137,191-195 (2000). 

Fig. 6.13 Ionic conductivity of proton-conductive perovskite type oxides, reported by Kreuer [156] (Reproduced by permission of Annual Reviews)...

Fig. 3.5 Conductivities of typical proton conducting perovskite-type oxides under H2-containing atmosphere...

Table 3.2 Typical examples of host oxides for proton conducting perovskites and their distinctive features...

Some perovskite-type oxides show protonic conduction and are useful for hydrogen-related electrochemical devices, including application to solid oxide fuel cells (SOFCs). Iwahara et al. reported protonic conductivity of strontium-cerate-based perovskite-type oxides in 1981 [1], Since that time, various perovskite-type proton-conducting oxides have been found. For use of the proton-conducting perovskite oxides, we should understand not only their merits but also their weak points. This chapter concerns the protonconducting properties of typical cerium- and zirconium-containing perovskite oxides from the points of view of conductivity, stability, electrode affinity, and dopant effect. Mixed conduction occurring in a special composition of the perovskite oxide is also introduced. 

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