中文摘要：

采用改进的柠檬酸法合成了Sc掺杂的锰酸锶镧（LSM）材料（LSMS），即La0．8Sr0.2Mn1-xSxO3±δ（简写为LSMSx，x=0，0．02，0．05和0．1）复合氧化物．采用X射线衍射（XRD）、程序升温还原（H2-TPR）及电化学方法分别对合成材料的结构、还原行为及以LSMSx—YSZ（即LSMSx与8％Y2O3掺杂的Zr02复合物）为阴极的中温固体氧化物燃料电池的性能进行了表征．XRD结果表明，在焙烧温度900℃、Sc掺杂量较低（x〈0．1）时LSMS材料能形成纯钙钛矿结构，随着掺杂量和焙烧温度提高，LSMS发生了不同程度的Sc2O3偏析现象．H2-TPR结果表明，焙烧温度对材料还原峰的形状和温度影响较大．由于Sc的掺杂以及Sc2O3的析出在样品结构中引人了结构缺陷，提高了LSMS中Mn^4＋和氧空位的浓度，加快了体相氧的迁移，改善了材料的还原性．但是随着Sc含量和焙烧温度提高，Sc掺杂对样品的还原活性改善不明显，这是由于Sc2O3偏析量增加引起的．电化学方法表征结果表明，LSMSx-YSZ复合阴极电池性能受Sc掺杂量、操作温度及阴极焙烧温度的影响．在本研究的掺杂范围内，Sc的掺杂显著提高了LSM基阴极低温操作的性能．这主要是由于Sc掺杂LSMS-YSZ复合阴极中氧空位的数目增加，导致阴极对氧还原反应的电化学活性提高，改善了LSM基阴极由于氧空位不足引起低温下极化损失严重的问题．

英文摘要：

La0.8Sr0.2Mn1-xScxO3-δ（abbreviated as LSMSx, x = 0, 0.02, 0.05, and 0.1） samples were prepared using a modified Pechini method. X-ray diffraction （XRD） and temperature-programmed reduction （H2-TPR） were carried out to characterize the structure and the reduction behavior of the LSMSx samples. Electrochemical evaluation was employed to assess the performance of intermediate-temperature solid oxide fuel cells （IT-SOFCs） using LSMSx-based cathode. XRD analysis indicated that the pure perovskite structure could only be obtained at the sintering temperature of 900℃ and lower Sc doping concentration （x 〈 0.1）. As the increase of sintering temperature and Sc doping concentration, the Sc2O3 secondary phase tended to segregate from the perovskite structure. The H2-TPR profiles of LSMSx samples were greatly affected by the sintering temperature. The substitution-induced improvement in reducibility for LSMS samples was detected, which might be ascribed to the increases of Mn^4＋ and oxygen vacancies. It can also be found that the increase of Sc203 separation possibly brought adverse effect to the reducibility of LSMS samples. Electro- chemical evaluation results showed that the performance of the cells with different cathodes was affected by the Sc doping concentration, operation temperature, as well as the cathode sintering temperature. In the range of Sc doping concentration studied , LSMS- based cathode materials showed higher lower-temperature performance than Sc free LSM-based materials. This is primarily due to the increase of substitution-induced oxygen vacancies, which improved the electrochemical activity towards oxygen reduction for LSM- based cathode materials.