Sr_(0.9)Y_(0.1)CoO_(3--δ)致密扩散障碍层极限电流型氧传感器的制备及性能

Preparation and Property of Limiting Current Oxygen Sensor with Sr_(0.9)Y_(0.1)CoO_(3--δ) Dense Diffusion Barrier Layer

采用固相合成法制备SrO.9Y0.1CoO3-δ（sYcO）混合导体和Lao.8sr0．2Ga0.83Mgo.1702．815（LSOM）固体电解质，利用X射线衍射仪、扫描电子显微镜、能谱仪、热重分析仪、热膨胀仪和碘滴定法对SYCO性能进行了表征。以SYCO为致密扩散障碍层，LSGM为氧泵层，采用瓷片复合法制备出致密扩散障碍层极限电流型氧传感器，研究了温度和氧含量对传感器性能的影响。结果表明：SYCO晶体为立方相Pm3m空间群结构；SYCO致密扩散障碍层致密且气孔较少，各元素的摩尔比基本符合SYCO的化学计量比；350～1000℃条件下，SYCO的线膨胀系数为25×10-6／℃；SYCO的非化学计量数δ为-0．143。中低温条件下（600-800℃），氧传感器具有良好的极限电流平台，在700℃（氧含量为0．91％～3．95％）和750℃（氧含量为0．98％～4．00％）条件下，提出了极限电流h与氧含量关系曲线。

SrO.9Y0.1CoO3-δ（SYCO） mixed conductor and Lao.8sr0.2Ga0.83Mgo.1702.815 （ LSGM ） solid electrolyte were pre- pared v/a solid-state reaction. The performances were determined by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopyj thermogravimetrie analysis, thermal expansion measurement and iodometric titration test, respective- ly. A limiting current oxygen sensor was prepared with the SYCO as a dense diffusion barrier and the LSOM as a solid electro- lyte by a ceramic composite method. The oxygen sensitive characteristic was measured at different temperatures and oxygen concentrations. The results show that the crystal structure of the SYCO belongs to Prn3m, the ceramic body is denser with a few of holes, and the mole ratio of the elements approximately equals to the stoichiometric ratio of St0.9 Y0.1CoOa-δ, The ther- mal expansion coefficient is 25 X 10-6/℃ at 350-1 000 ℃ and the nonstoichimetric number, δ, is -0. 143. At 600-800℃, the sensor exhibits a better limiting current platform. The empiric formulas between the limiting current and the oxygen concentra- tion at 700 ℃（the oxygen concentration of 0. 91-3.95 %） and 750 ℃ （the oxygen concentration of 0. 98 %-4.00%） were proposed,