Proton and oxide ion conductivity of doped LaScO3

The conductivity of La0.9Sr0.1Sc0.9Mg0.1O3 has been studied by impedance sp ectroscopy in controlled atmospheres. The material was found to be a mixed conductor with p-type conduction at high oxygen partial pressures and a com bined proton and oxide ion conductor at low oxygen partial pressures. At te mperatures below 800 degrees C and low partial pressure of oxygen, proton c onduction was dominant. Above this temperature, the ionic conductivity is d ominated by oxide ion transport. The protonic transport number was estimate d from the conductivities measured in dry and in water-moisturised gas. An isotope effect was observed using D-2/D2O in place of H-2/H2O. The oxygen t ransport number was estimated from this effect and from measurements in a t wo-chamber electrochemical cell. (C) 1999 Elsevier Science B.V. All rights reserved.