| 内容提要: |
Samarium doped ceria (Ce0.8Sm0.2O1.9, SDC) as a promising electrolyte material for solid oxide fuel cells (SOFCs) has been extensively researched for its higher ionic conductivity at intermediate temperature compared with standard yttria-stabilized zirconia. However, SDC exhibits mixed electronic and ionic conduction, especially at low oxygen partial pressure, which results in an inner short-circuit and lower the open circuit voltage of SOFC.In this work, the electronic conductivity of SDC was measured with the modified electromotive force (e.m.f.) method which is an effective technique to determine the minor electronic contributions to the total conductivity of the mixed ionic and electronic conductors. Besides, an innovative concentration cell with a reference electrode was constructed to combine the e.m.f. method with three-electrode system to verify the effectiveness of the modified e.m.f. method. The oxygen ionic transport number of SDC is approximately 1 below 600 oC with the consideration of electrode polarization. However, as the temperature rises, the p-type electronic conduction in SDC becomes non-negligible, and the oxygen ionic transport number reduces to 0.956 at 700 oC. |