Proton and oxide-ionic conduction in Sr- and Zn-doped LaGaO3

The ionic conduction behaviors in La0.9Sr0.1Ga0.9 Zn0.1O3-a under different atmospheres at 600–1,000 Cwere studied by various electrochemical methods including ac impedance, hydrogen and oxygen concentration cells, electrochemical hydrogen and oxygen pumping, etc. The proton conduction in this oxide was investigated for the first time. The hydrogen concentration cell and oxygen concentration cell showed stable electromotive forces close to the theoretical ones calculated from Nernst’s equation, indicating that the conduction was almost pure ionic under hydrogen atmosphere or dry oxygen atmosphere. The electrochemical hydrogen pumping rates coincided with the theoretical ones calculated from Faraday’s law, confirming that La0.9Sr0.1Ga0.9Zn0.1O3-a is a proton conductor under hydrogen atmosphere. A similar result for electrochemical oxygen pumping was obtained, indicating that it is an oxideionic conductor under dry oxygen atmosphere. The ionic conductivity was about 0.06 S cm-1 at 1,000 C.