BULK CONDUCTIVITY AND DEFECT CHEMISTRY OF ACCEPTOR-DOPED STRONTIUM-TITANATE IN THE QUENCHED STATE

The grain bulk conductivity of acceptor-doped SrTiO3 ceramics was investigated by the impedance analysis method after quenching from high-temperature equilibria. The influence of the oxygen partial pressure during equilibration, P(O2)Eq, is described in terms of a defect model for titanates. From a comparison between the experimental results and the predictions of this model, a predominant ionic conductivity is concluded for a wide P(O2)Eq range (approximately 10(-11) to 10(5) Pa). The influence of the ionization energy of the acceptors and of possible defect association is discussed.