尿素燃烧法合成La_(0.8)Sr_(0.2)FeyCo_(1-y)O(3-δ)及其性能表征

Urea Combustion Synthesis and Characterization of La_(0.8)Sr_(0.2)FeyCo_(1-y)O(3-δ)

采用尿素燃烧法合成了中温固体氧化物燃料电池阴极材料La0.8Sr0.2FeyCo1-yO3-δ粉体。分别利用TG-DSC、XRD和SEM对产物的形成过程、晶体结构和显微形貌进行了研究。结果表明,La0.8Sr0.2FeyCo1-yO3-δ粉体的主晶相为钙钛矿结构,个别试样伴有少量杂峰。采用直流四端子法测试了烧结后试样在500℃~800℃范围内的电导率,实验结果表明,y=0时,样品的电导率最大,且随温度升高而单调下降呈金属型导电;其它样品（y=0.20,0.25,0.30,0.35,0.40）的电导率随温度升高而增大,符合小极化子导电机制;在测试温度范围内,材料的电导率均大于400S/cm。

The La0.8Sr0.2FeyCo1-yO3-δ powders, used as a cathode material for intermediate temperature sohd oxide fuel cell, were synthesized by a urea combustion method. The formation process, crystal structure and micrograph of the as - synthesized samples were investigated by TG - DSC, XRD and SEM, respectively. The results show that the major phase of the as - synthesized powders is per- ovskite structure, whereas some weak impurity peaks exist in the samples. The diffraction peak shifts towards low angle with Fe contment increasing. The electrical conductivities of the samples were measured by four point electrode method at 500℃- 800℃ in air. The results indicate that the electrical conductiivity of the La0.8Sr0.2FeyCo1-yO3-δ reduces with increasing Fe content, and decreases monotonously with temperature, implying that the conduction mechanism of the La0.8Sr0.2FeyCo1-yO3-δ is consisitent with the metallic- hke behavior. The electrical conductivity of samples widl y = 0.2 - 0.4 increases with temperature, suggesting that the conduction mechanism is identical to the small polarons hopping mechanism. The electrical conductivity of all samples is kigher than 400S/cm at 500℃ - 800℃.