【作者】 石海；

【导师】 徐庆；

【作者基本信息】 武汉理工大学 ， 材料学， 2008， 硕士

【摘要】 La₂NiO_4+δ和La_0．6Sr_0．4Co_0．2Fe_0．8O_3-δ具有电子-离子混合导电特性，是中温固体氧化物燃料电池（SOFC）阴极的候选材料。本论文选择La₂NiO_4+δ与La_0．6Sr_0．4Co_0．2Fe_0．8O_3-δ为组元，设计并制备出（100-x）wt．％La₂NiO_4+δ+xwt．％La_0．6Sr_0．4Co_0．2Fe_0．8O_3-δ（x=10-60）复合体系阴极材料，研究了烧结温度和组成对复合体系阴极材料结构和性能的影响，其目的在于为研制具有优良综合性能的新型阴极材料提供科学依据。本论文考查了复合体系材料中两组元在高温下的化学相容性。XRD测试结果显示，复合体系陶瓷样品的衍射峰可分别归属为La₂NiO_4+δ组元和La_0．6Sr_0．4Co_0．2Fe_0．8O_3-δ组元的衍射峰，说明复合阴极两组元La₂NiO_4+δ和La_0．6Sr_0．4Co_0．2Fe_0．8O_3-δ在高温下有无明显化学反应，具有良好的化学相容性。本论文研究了烧结温度对La₂NiO_4+δ-La_0．6Sr_0．4Co_0．2Fe_0．8O_3-δ复合体系陶瓷结构与导电性能的影响。研究结果表明，适当的提高烧结温度可以明显改善陶瓷的显微结构和导电性能。根据导电性能测试结果确定，x=60的复合体系陶瓷样品的合适烧结温度为1400℃，其它组成的复合体系陶瓷样品的合适烧结温度为1450℃。本论文研究了组成对La₂NiO_4+δ-La_0．6Sr_0．4Co_0．2Fe_0．8O_3-δ复合体系陶瓷结构与性能的影响。研究结果显示，随复合体系陶瓷中La_0．6Sr_0．4Co_0．2Fe_0．8O_3-δ组元相对含量的增加，复合体系陶瓷的总电导率提高、氧离子电导率降低、热膨胀系数增大。根据导电性能和热膨胀性能的研究结果确定，x=30的组成为该复合体系阴极材料的最佳组成。在600℃-800℃温度范围内，其总电导率保持在100 S·cm^-1以上；在100℃-730℃温度范围内，其平均热膨胀系数为14．4×10^-6K^-1。在导电性能和热膨胀性能上，该组成满足中温SOFC对阴极材料的性能要求。更多还原

【Abstract】 La₂NiO_4+δ（LN） and La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ （LSCF） are current candidate materials for cathodes of intermediate temperatures solid oxide fuel cells （SOFC） because of their electronic-ionic conducting properties. In this work, （100-x）wt.% LN-xwt.% LSCF （x=10-60） composite cathodes have been designed and prepared with the LN and LSCF as the two components. The effects of sintering temperature and composition on the structure, chemical stability, mixed conducting properties and thermal expansion behaviors of the composite cathodes have been investigated from the viewpoint of seeking for the preferred compositions with both the desired electrical conducting and thermal expansion properties.The chemical compatibility between the LN and LSCF at high temperatures has been investigated. X-ray diffraction （XRD） analysis was employed to examine the phase structure of the composites after annealing at 1450℃. The results indicated that the XRD peaks of the composites can be assigned to those of the two end members, respectively. No significant solid state reaction product was detected between the two components during the annealing, demonstrating an acceptable chemical compatibility for the LN and LSCF.The effects of sintering temperature and composition on the mixed conducting and thermal expansion properties of the composite cathodes have been investigated. The preferred sintering temperatures have been ascertained for the composites in terms of the electrical conductivity data. The composition with x=60 presented the highest electrical conductivity when sintering at 1400℃, while the other compositions showed a preferred sintering temperature of 1450℃. It has been found that increasing the relative content of LSCF resulted in a rise of electrical conductivity, a decrease of ionic conductivity and an increase of thermal expansion coefficient （TEC）.The preferred composition was determined to be 70wt.% LN-30wt.% LSCF with respect to both the electric conductivity and TEC data. The composition exhibited electrical conductivities above 100 S·cm^-1 in the temperature range of 600℃-800℃and a TEC of 14.4×10^-6K^-1 averaged between 100℃-730℃.更多还原