Samples of proton-conducting acceptor-doped perovskite-type alkaline-earth cerates, zirconates, niobates and titanates were investigated experimentally, and via numerical simulation. In all of the cubic perovskites, the concentration of protonic defects almost reached the acceptor-dopant concentration under certain conditions, and the mobility of protonic defects fell within a narrow range. However, any reduction in symmetry led to a reduction in the concentration and mobility of protonic defects. In all of the oxides, dynamic H-bonding was suggested to lead to a local lattice-softening which provided an advantageous environment for high proton-mobility. This effect was suggested to explain a very high proton conductivity of covalent acceptor-doped BaZrO3; which was found experimentally here for the first time. This oxide also exhibited good thermodynamic phase stability.

Aspects of the Formation and Mobility of Protonic Charge Carriers and the Stability of Perovskite-Type Oxides. K.D.Kreuer: Solid State Ionics, 1999, 125[1-4], 285-302