Kd. Kreuer, Aspects of the formation and mobility of protonic charge carriers and the stability of perovskite-type oxides, SOL ST ION, 125(1-4), 1999, pp. 285-302
Proton conducting acceptor-doped perovskite-type alkaline earth cerates, zi
rconates, niobates and titanates have been investigated experimentally and
by numerical simulations. For all cubic perovskites the concentration of pr
otonic defects almost reaches the acceptor dopant concentration under appro
priate conditions, and the mobility of protonic defects fall into a narrow
range. Any symmetry reduction, however, leads to a reduction of the concent
ration and mobility of protonic defects. For all oxides, dynamical hydrogen
bonding is suggested to lead to a local lattice softening, which provides
an advantageous environment for high proton-mobility. This effect may expla
in the very high proton conductivity in covalent acceptor-doped BaZrO3, whi
ch has been found experimentally for the first time. Since this oxide also
shows good thermodynamic phase stability, it is an interesting candidate as
separator material in high-drain electrochemical applications such as fuel
-cells. (C) 1999 Elsevier Science B.V. All rights reserved.