Barium cerate

McFarlan, A., Pelletier, L., and Maffei, N., An intermediate-temperature ammonia fuel cell using Gd-doped barium cerate electrolyte, /. Electrochem. Soc., 151(6), A930, 2004. 

The protons migrate mainly as lone protons, and jump from lattice site to lattice site by the Grotthus mechanism. The protonic conductivity of zirconates (Ca,Sr, Ba) ZrOj] is approximately one order of magnitude louver than that of the cerates ho vever, their chemical and mechanical stabilities are superior. In contrast to cerates, zirconates barely react vith carbon dioxide gas. The stability of barium cerates can be increased vhen cerium atoms are partially substituted by zirconium atoms. 

Consequently, we are in the startup phase of our program. Our first task was to identify candidate perovskite oxide materials with high protonic conductivities. We have identified ytterbium doped strontium cerate and yttrium doped strontium zirconate materials as possible electrolyte materials. Barium cerate perovskites exhibit higher protonic conductivity, but the reactivity with carbon dioxide would require pretreatment of the steam. 

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... 

Shima D, Htiile SM. The influence of cation non-stoichiometry on the properties of undoped and Gadolinia-doped barium cerate. Solid State Ionics. 1997 97(l ) 443-55. 

Stevenson DA, Jiang N, Buchanan RM, Henn PEG. Characterization of Gd, Yb and Nd doped barium cerates as proton conductors. Solid State Ionics. 1993 62(3-4) 279-85. 

Carneim RD, Armstrong TR. Chemical stability of Barium cerates-based high temperature proton conductors. 225th American Chemical Society National Meeting - Fuel Division Preprint, New Orleans, LA, 2003. 

Rauch WL, liu M. BaCuGd205 — BaCeOs composite cathodes for barium cerate-based electrolytes. J Electrochem. Soc. 1997 144(ll) 4049-54. 

Decomposition of Yttrium-Doped Barium Cerate in Carbon Dioxide... 

Two methods for improving the stability of yttrium-doped barium cerate in CO2 have been investigated. Producing slightly barium-deficient compositions and... 

Nevertheless, cerate samples easily degrade as they react to form insulating barium carbonate (BaCOj) and cerium oxide (C O2), when exposed to atmosphere containing CO2 and H2O in a working environment (Gopalan and Virkar, 1993 Schober, 2003). Compared with doped cerates, doped zir-conates have better chemical stability but lower conductivity. The stability of doped-barium cerates could be improved by the introduction of Zr at B site in order to achieve high proton conductivity and sufficient chemical stability in fuel cell operation conditions. 

Su X-T, Yan Q-Z, Ma Y-H, Zhang W-F and Ge C-C (2006), Effect of co-dopant addition on the properties of yttrium and neodymium doped barium cerate electrolyte . Solid State Ionics, 177,1041-1045. 

It is well known that, in general, BaCeOs oxides have higher protonic conductivity than SrCe03-based oxides. The increase of protonic conductivity in membrane material would be beneficial. A large number of cells with a barium cerate membrane were used in electrocatalytic ammonia synthesis. The results showed that there is no significant improvement between cells with SrCe03-based or BaCeOa.based oxides. It can be concluded that materials with protonic conductivity of 10 —10 S/cm would be adequate for ammonia synthesis. 

Akoshima, S., Oishi, M., Yashiro, K., Sato, K., Mizusaki, J. (2010). Reaction kinetics on platinum electrode/yttrium-doped barium cerate interface under H2—H2O atmosphere. Solid State Ionics, 181, 240—248. 

Taniguchi, N., Hatoh, K., Niikura, J., and Gamo, T. (1992). Proton conductive properties of Gd-doped barium cerates at high temperatures. Solid State Ionics 53-56 998-1003. 

WienstrOer, S., and WiemhOfer, H. D. (1997). Investigation of the influence of zirconium substitution on the properties of neodymium-doped barium cerates. Solid State Ionics 101-103 1113-1117. 

H. Maekawa, Y. Ukei, K. Morota, N. Kashii, J. Kawamura, T. Yamamura, High temperature proton NMR study of yttrium doped barium cerates, Sohd State Commun. 

Although oxide ion conducting oxides have traditionally been used as the separating electrolyte, interest in proton conducting oxides for SOFC electrolytes has been growing [86, 87]. Perovskites such as barium cerate have been shown to be ideal for candidate materials and have been the subject of intense research [88]. Although a full discussion of these materials... 

Matsumoto H, Nomura I, Okada S, Ishihara T (2008) Intermediate-temperature solid oxide fuel cells using perovsldte-t3 pe oxide based on barium cerate. Solid State Ionics 179 1486-1489... 

Knight KS, Soar M, Bonanos N (1992) Crystal-structures of gadolinium-doped and yttrium-doped barium cerate. J Mater Chem 2(7) 709-712... 

Knight KS, Bonanos N (1995) A high-resolution neutron powder diffraction study of neodymium doping in barium cerate. Solid State Ionics 77 189-194... 

Yang, R, Tebano, A., Di Castro, D., Balestrino, G., D Epifanio, A., Licoccia, S., and Di Bartolomeo, E. (2014) Deposition and electrochemical characterization of yttrium doped barium cerate and... 

Scholten, M.J., Schoonman, J., Miltenburg, J.C., and Oonk, H.A.J. (1993) Synthesis of strontium and barium cerate and their reaction with carbon dioxide. Solid State Ionics, 61, 83-91. 

Agarwal V., Liu M. Preparation of barium cerate-based thin films using a modified Pechini process. J. Mater. Sci. 1997 32 619-625... 

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