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The effect of oxide (La 0.9 Sr 0.1 MnO 3 , LSM) coating on the commercial stainless steel (STS444) interconnect as SOFC interconnect was examined by measuring the polarization resistance (R p ) of LSCF (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 ) cathodes of various electrolyte-supported cells (La 0.9 Sr 0.1 Ga 0.. The electrochemical impedance of LSCF cathodes was monitored during ∼140 h in air at 600 and 700°C to determine the cathodic R p values. With or without interconnect contacts, the magnitude of cathodic R p value of LSGM electrolyte was similar to that of GDC electrolyte and much smaller than that of YSZ electrolyte. However, no apparent difference in the rate of increase was observed among the cathodes on the different electrolytes. Although the R p value of the LSCF cathode in contact with LSM-coated STS444 was much reduced from that with uncoated STS444, the coating was not perfect to prevent the Cr evaporation from the interconnect and thus to avoid the degradation of LSCF cathode. Thus new coating methods or materials are needed to protect the LSCF cathode from the Cr poisoning.

SUMMARYThe effect of P and V contents on the microstructure and thermoelectric properties of Fe 2-x M x O 3 (M: P and V; 0 ≤ x ≤ 0.01) is studied. Higher P and V contents result in increases of both the grain size and density, thus increasing the electrical conductivity. The absolute values of the Seebeck coefficients of the Fe 2-x P x O 3 and Fe 2-x V x O 3 increase with increasing P and V contents up to x = 0.0075 and 0.005, respectively, and then decrease with further increase of its concentration. The addition of a small amount of V (0.005) to Fe 2 O 3 leads to a marked increase in both the electrical conductivity and Seebeck coefficient. This means that the introduction of a small amount of V is highly effective for improving the thermoelectric properties of Fe 2 O 3 .