Electrical resistivity measurements were carried out on pellets, at 298 to 1000K, using alternating-current impedance spectroscopy and direct-current methods in dry or moist air and 8%H2-Ar environments. The conductivity of unsintered pellets between 298 and 500K ranged from 10-3 to 10-7S/cm, and was attributed to extrinsic hydroxyls. An acceptor-doped composition, BaTi0.9Fe0.1O3-δ▪2δ(OH), exhibited a higher conductivity than that of BaTiO3 or of donor-doped Ba0.9Nd0.1TiO3-δ▪2δ(OH) in moist air. Hydrothermally prepared powders which were heat treated below 1000K had cubic symmetry at room temperature, possessed a higher proton conductivity and re-absorption capability for hydroxyls upon exposure to moisture, than did powders which were sintered at 1673K (tetragonal symmetry). The conductivity at 298 to 500K was due to the mobility of protons along O---H---O octahedra in the perovskite lattice. The conduction at 550 to 1000K was the combined effect of proton as well as O-vacancy mobility in BaTiO3 and Ba0.9Nd0.1TiO3.

Proton Transport and Structural Relations in Hydroxyl-Bearing BaTiO3 and its Doped Compositions Synthesised by Wet-Chemical Methods. H.Jena, K.V.G.Kutty, T.R.N.Kutty: Materials Research Bulletin, 2004, 39[3], 489-511