OXYGEN PERMEATION MEASUREMENT OF LA1-XCAXCRO3-DELTA BY USING AN ELECTROCHEMICAL METHOD

Oxygen permeation current density (J(O2-)) through La0.9Ca0.11CrO3-del ta was measured by using an electrochemical method under an oxygen pot ential gradient, P(O-2)=1 similar to 1x10(-13) bar. The oxygen vacancy diffusion coefficient (D-V) is estimated 1.5x10(-10) m(2) s(-1) in th e P(O-2) range from 10(-5) to 10(-10) bar. The oxygen permeation curre nt density through 1 mm thick plate is estimated as 10 mA cm(-2) in SO FC operation condition. The oxygen tracer diffusion coefficients via b ulk (D) and via grain boundary (D-gb*) were estimated by SIMS for La1 -xCaxCrO3-delta (x=0.1, 0.2). The contribution of grain boundary diffu sion on permeation was considered in the oxidizing atmosphere, however , the bulk diffusion is dominant in a large oxygen potential gradient.