Oxygen diffusivity in cation-defective lanthanum manganite

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:472045

Morin, F; Trudel, G ^[1]; Denos, Y ^[2]

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1. Hydro-Quebec Research Institute (IREQ), Quebec (Canada)
2. INRS-Energie et Materiaux, Quebec (Canada)

Strontium-substituted manganite is prevalently used as the air electrode material in solid oxide fuel cells (SOFCs). At high oxygen partial pressures (p{sub O2}`s), it is known to be oxygen-rich while it becomes oxygen-deficient at low p{sub O2}`s. The chemical diffusivity in dense La{sub 1.02}MnO{sub 3{+-}{delta}} and La{sub 0.97}MnO{sub 3{+-}{delta}} has been measured by means of the chemical gradient relaxation method and compared to that of strontium-substituted manganite. Measurements were performed thermo-gravimetrically and by means of electric conductivity at temperatures between 800 and 1250{degrees}C in both oxidizing-reducing mixtures and pure oxygen. High diffusivities have been obtained in La{sub 1.02}MnO{sub 3{+-}{delta}}, comparable to those already observed for strontium-substituted lanthanum manganite. Diffusivity is reduced by at least an order of magnitude with the combined effects of a lanthanum-poor manganite and the high p{sub O2} region. Peculiarities of both measuring methods are discussed and so are the differences in reequilibration behavior between the low and and the high p{sub O2} regions.

• OSTI ID: 472045
• Report Number(s): CONF-950401--
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
36 MATERIALS SCIENCE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
LANTHANUM OXIDES
MANGANESE OXIDES
MEASURING METHODS
SOLID ELECTROLYTE FUEL CELLS
TIME DEPENDENCE