La_(0.7)Sr_(0.3)Co_(1-y)Fe_yO_(3-δ)阴极材料的制备与导电性能研究

Preparation and electrical properties investigation of La_(0.7)Sr_(0.3)Co_(1-y)Fe_yO_(3-δ)

采用低温燃烧合成法制备了用作中低温固体氧化物燃料电池的阴极材料La_(0.7)Sr_(0.3)Co_(1-y)FeyO_(3-δ) (y=0.00,0.20,0.25,0'30,0.35,0.40)。分别利用TG-DSC、XRD表征了La_(0.7)Sr_(0.3)Co_(1-y)FeyO_(3-δ)形成过程的晶型演化行为和物相组成,结果表明该粉体经900℃热处理后可形成钙钛矿结构,随着Fe含量增加,衍射峰向低角度方向偏移。利用直流四端子法测试了La_(0.7)Sr_(0.3)Co_(1-y)FeyO_(3-δ)的电导率,结果表明样品的电导率随Fe含量的增加而降低。在所测量的温度范围内,y=0样品的电导率随温度升高而减小,符合类金属导电行为;其余样品的电导率随温度的升高而增大,服从半导体导电机理。在测试温度范围内,材料的电导率均大于600 S·cm^(-1)。

The La0.7Sr0.3Co1-yFeyO3-δ powders were synthesized by a low temperature combustion method. The synthesizing process and the phase of the La0.7Sr0.3Co1-yFeyO3-δ powders were characterized by TG-DSC and XRD, respectively. The results showed that all samples form perovskite structure after sintered at 900℃, whereas some weak impurity peaks exist in the samples. The diffraction peak shifts towards low angle with Fe content increasing. The electrical conductivity of LSCF was measured by the D.C. four probes technique. The electrical conductivity of the samples decreases with Fe substitution increasing. The electrical conductivity of the La0.7Sr0.3CoO3 decreases with temperature increasing, exhibiting a metallic-like conducting behavior. While the electrical conductivity of the other samples increases with temperature increasing, showing a semi-conducting behavior. In the measured temperature range ,the electrical conductivity of all samples is higher than 600S· cm^-1.