Dense La
0.4Sr
0.6Co
0.2Fe
0.8O
3-![](/images/gifchars/delta.gif)
oxygen-permeable membranes of different thickness wereprepared by solid-state reaction. The oxygen flux facilitated by an oxygen partial pressuredifference across the oxide membrane was measured at elevated temperatures. It is revealedthat oxygen permeation flux is entirely controlled by the transport of oxide ions in the bulkof the membrane in the thickness range of 1.25-2.46 mm. When the thickness is decreasedto 0.62 mm, it becomes jointly controlled by the oxygen exc
hange across the gas and solidinterfaces. An electrochemical approach is adopted to analyze the thickness dependence ofthe oxygen flux. It is shown that the interfacial process is more sensitive to the c
hange oftemperature, as evidenced by the larger activation energy for the surface oxygen exc
hange(188.2 ± 2.2 kJ mol
-1), than that for the bulk transport (93.7 ± 1.7 kJ mol
-1).