Water incorporation and proton conductivity in titanium substituted barium indate

Water uptake in the perovskite-like oxygen deficient compounds Ba-2(In1-xTix)(2)O5+x square(1-x) (0 <= x<0.7) (called BITx) was investigated by thermal gravimetric analysis (TGA) at equilibrium conditions and thermodynamic data of the hydration process were extracted. The change of the lattice volume upon hydration, inferred from X-ray diffraction data, appears as an important parameter for the characterization of perovskite-type proton conductors. The proton conductivity, the transport number and the proton diffusion coefficients for BITx compounds were determined from conductivity measurements performed under wet and dry atmosphere. The conductivity of Ba-2(In1-xTix)(2)O5+x square(1-x) compounds is mainly protonic up to 450 degrees C and the best level of proton conductivity was obtained for BIT02 with a value of 1.1 x 10(-3) S cm(-1) at 450 degrees C. (C) 2009 Elsevier B.V. All rights reserved.