Electrical properties and microstructure analysis of La1-xSrxCoO3-δ cathode material

• Main Authors: Peng-Yu Huang, 黃鵬宇
• Other Authors: 吳玉娟
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/ym2epa

碩士 === 國立臺北科技大學 === 材料及資源工程系研究所 === 99 === Purpose of this study was development of intermedium temperature solid oxide fuel cell (IT-SOFC) cathode materials to replace the La1-xSrxMnO3-δ which was used as traditional high-temperature SOFC cathode material. The La1-xSrxMnO3-δ shows low conductivity in the temperature range (500 oC ~ 800oC), thus we used LaCoO3 as base which shows higher conductivity. In this study, it found that electrical conductivity and ionic conductivity increased by doping Sr, and it also pointed out that the La1-xSrxCoO3-δ cathode materials showd higher conductivity than La1-xSrxMnO3-δ in 500oC to 800oC. The La1-xSrxCoO3-δ sample that is more suitable as IT-SOFC cathode material. In this study, we used solid-state reaction method to preparae La1-xSrxCoO3-δ (x = 0, 0.3, 0.4, 0.5, 0.6) cathode material, the sintering temperature was 1200oC and held for 2 hours and 6 hours. All samples were analyized by archimedes method, X-Ray diffractometer, scanning electron micoscope, transmission electron microscope, direct current resistance, alternating current impedance, thermal expansion analyzer and other instruments, to determine the relative density, crystal structure, microstructure, conductivity and impedance. XRD data shows, sintering temperature 1200oC /2 and 6 hours, can be found in the structure of the specimens are single phase perovskite structure. At 60 mole% substitution lanthanum with strontium, the crystal structure becomes cubic. In SEM analysis, the average grain size increased with sintering time. Therefore the average grain size also increased with strontium increased. In DC resistance analysis, LaCoO3 showed semiconducting behavior, La1-xSrxCoO3-δ (x = 0.3, 0.4, 0.5, 0.6) showed metallic conducting behavior. During 500oC ~700oC, the La0.6Sr0.4CoO3-δ-6h showd values of electrical conductivity ranging from 3260 S/cm at 500oC to 2425 S/cm at 700oC.