Oxygen permeability of perovskite-type Sro_(0.7)Ce_(0.3)MnO_(3-δ)

摘要

The average linear thermal expansion coefficient (TEC) of perovskite-type Sr_(0.7)Ce_(0.3)MnO_(3-δ), calculated from dilatometric data at 300-1100 K in air, is (11.9+-0.2) x 10~(-6) K~(-1), compatible with that of stabilized zirconia. The high electronic conductivity, 230-270 S/cm at 773-1273 K, and the moderate thermal expansion suggest possible application of Ce-doped strontium manganite as solid oxide fuel cell (SOFC) cathode material. The oxygen permeation fluxes through dense Sr_(0.7)Ce_(0.3)MnO_(3-δ) membranes at 1273-1173 K were found to linearly increase with the oxygen chemical potential gradient in the range of permeate-side oxygen partial pressures from 21 kPa down to 2 x 10~(-9) Pa, indicating a relatively high stability of this phase. However, the oxygen permeability of Sr_(0.7)Ce_(0.3)MnO_(3-δ), limited by both bulk ionic conductivity and surface exchange at the membrane/gas boundaries, is higher than that of La_(0.7)Sr_(3-δ)MnO_(3-δ), but still considerably lower if compared to La(Sr)Fe(Co)O_(3-δ) perovskites.