The conduction of H in SrTi1-xFexO3-x/2, where x ranged from 0 to 0.8, was investigated by means of alternating-current conductivity and concentration-cell emf transport number measurements at 500 to 1100C. The main contributions to the total conductivity were n-type electronic (which predominated at low O partial pressures), ionic (O vacancies predominated at intermediate partial pressures) and p-type electronic (at high O partial pressures. The H-ion conduction was measurable, but the H-containing species were minority defects (in terms of the concentration and conductivity at these temperatures). When the conditions were not too reducing, the H ions were positive and were assumed to be protons. At lower O partial pressures, there was a change in the sign of the emf of the water-vapour concentration cell and, apparently, in the charge on the H-containing charge-carrying species. These results could by rationalised in terms of the presence and migration of substitutionally dissolved hydride ions, but it was unclear whether these could be stable under the conditions used.

Hydrogen Ion Conduction in Iron-Substituted Strontium Titanate, SrTi1-xFexO3-x/2 (0 < x < 0.8). S.Steinsvik, Y.Larring, T.Norby: Solid State Ionics, 2001, 143[1], 103-16