COMPATIBILITY OF LA0.9SR0.1GA0.8MG0.2O2.85 AS THE ELECTROLYTE FOR SOFCS

The compatibility of La0.9Sr0.1Ga0.8Mg0.2O2.85 perovskite oxide as an electrolyte for solid oxide fuel cells (SOFCs) was (i)nvestigated. Aft er single SOFC tests using Pt as cathode and anode, the surface morpho logies of La0.9Sr0.1Ga0.8Mg0.2O2.85 were changed. For the cathode side , second phases were formed along grain boundaries, but there was no s ignificant change on the surface of grains. As for the anode side, two significant compositional changes were found by SIMS. The first is th at La0.9Sr0.1Ga0.8Mg0.2O2.85 reacted with other components such as alu mina tubes or Pyrex glass sealant in the test cell. The second is a si gnificant depletion of B-site ions, especially Ga ion, from the surfac e outside the effective electrode area in La0.9Sr0.1Ga0.8Mg0.2O2.85, a nd the surface morphology was changed from dense to porous. Because Ga monovalent compounds, such as Ga2O, have high vapor pressures in the reducing atmosphere around p(O-2) = 10(-24) atm, the Ga depletion can be ascribed to the vaporization of the Ga component. (C) 1998 Elsevier Science B.V. All rights reserved.