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采用溶胶–凝胶法制备了La0.8–xBaxSr0.2Co0.8Fe0.2O3–δ(LBSCF)阴极粉体。对LBSCF的晶体结构、材料表面的化学状态、烧结体的断面微结构及电导率进行了表征。用交流阻抗谱法在550~700℃范围测试了LBSCF-30%SDC(Sm0.2Ce0.8O1.9)复合阴极的电化学性能。结果表明:LBSCF粉体主晶相为六方晶系钙钛矿结构,存在少量的第二相。XPS结果显示,Ba2+掺杂不影响A位离子(La3+、Ba2+、Sr2+)的价态,但对B位离子的价态有不同的影响:x=0.10的样品中,钴离子以Co3+和Co4+混合价态存在,其余样品中以低氧化态(Co3+和Co2+混合价)或Co3+价存在;铁离子以高氧化态(Fe3+和Fe4+)存在。在500~700℃空气气氛中,LBSCF的电导率均超过700 S/cm,在同一温度下,电导率随着Ba2+掺杂量的增加而增大。x=0.20的样品在500℃时,电导率最大可达1.59×103 S/cm。随着Ba2+含量增加,极化电阻减小,x=0.20时,复合阴极LBSCF-30%SDC的极化电阻最小,700℃时的极化电阻为0.20?·cm2。
La0.8-xBaxSr0.2Co0.8Fe0.2O3-δ (LBSCF) cathode powders were prepared by sol-gel method. The crystal structure of LBSCF, the chemical state of the surface of the material, the microstructure and the conductivity of the sintered body were characterized. The electrochemical performance of LBSCF-30% SDC (Sm0.2Ce0.8O1.9) composite cathode was tested at 550-700 ℃ by AC impedance spectroscopy. The results show that the main crystal phase of LBSCF is hexagonal perovskite structure with a small amount of second phase. The results of XPS showed that the Ba2 + doping did not affect the valences of the A-site ions (La3 +, Ba2 +, Sr2 +) but had a different effect on the valences of the B site ions: cobalt ions were mixed with Co3 + and Co4 + In the other samples, the low oxidation states (Co3 + and Co2 + mixed valences) or the Co3 + valence exist. The iron ions are present in high oxidation states (Fe3 + and Fe4 +). The conductivity of LBSCF exceeds 700 S / cm in air at 500-700 ℃, and the conductivity increases with the increase of Ba2 + doping at the same temperature. The conductivity of the sample with x = 0.20 is up to 1.59 × 103 S / cm at 500 ℃. As the content of Ba2 + increases, the polarization resistance decreases. When x = 0.20, the polarization resistance of the composite cathode LBSCF-30% SDC is the smallest, and the polarization resistance at 700 ℃ is 0.20? Cm2.