Kenichi Hiwatashi

Determination of the Oxygen Permeation Flux Through La0.75Ca0.25CrO3 − δ by an Electrochemical Method

The oxygen permeation flux measured as the oxide ion current density (J O 2-) through La 0.75 Ca 0.25 CrO 3-δ was determined at steady state by using an electrochemical method in the p O2 range from 10 5 to 10 -1 1 Pa at T = 1273 K. The oxygen vacancy diffusion coefficient (D v ) is estimated to be 1.5 X 10 -9 m 2 s -1 in the p O2 region from 1 to 10 -5 Pa. When p O2 is lower than 10 -5 Pa, J O2 - seems to depend on a surface reaction as the rate-determining step. The contribution of grain-boundary diffusion on permeation was considered in the oxidizing atmosphere. The oxygen permeation current density through a 1 mm thick plate is estimated as 0.03 A cm -2 in the solid oxide fuel cell operation.

Determination of the oxygen permeation flux through La{sub 0.75}Ca{sub 0.25}CrO{sub 3{minus}{delta}} by an electrochemical method

The oxygen permeation flux measured as the oxide ion current density (J O 2-) through La 0.75 Ca 0.25 CrO 3-δ was determined at steady state by using an electrochemical method in the p O2 range from 10 5 to 10 -1 1 Pa at T = 1273 K. The oxygen vacancy diffusion coefficient (D v ) is estimated to be 1.5 X 10 -9 m 2 s -1 in the p O2 region from 1 to 10 -5 Pa. When p O2 is lower than 10 -5 Pa, J O2 - seems to depend on a surface reaction as the rate-determining step. The contribution of grain-boundary diffusion on permeation was considered in the oxidizing atmosphere. The oxygen permeation current density through a 1 mm thick plate is estimated as 0.03 A cm -2 in the solid oxide fuel cell operation.