Study On La_1-xSr_xMnO₃ Prepared By Self-propagating High-temperature Synthesis

Solid Oxide Fuel Cell (SOFC), as a new way of power generation, exhibits a great potential in solution of energy crisis and environmental pollution, and gets a wide attention in recent year. SOFC is composed by cathode, electrolyte, anode and interconnect. From the viewpoint of the high electrical conductivity, low reactivity and good compatibility with YSZ, La1-xSrxMnO3(LSM)is considered to be the most popular cathode materials for SOFC. However, the high cost of LSM prepared by traditional technology such as solid state sintering and sol-gel method hinders the application and industrialization of SOFC. Therefore, it is important to explore a new synthesis method for reducing the high cost of preparing LSM.In this paper, La1-xSrxMnO3 was prepared by self-propagating high-temperature synthesis (SHS) which was an effective way in reducing the cost of preparation. Four systems of SHS reaction that included nine reaction formulas were found to synthesize LSM. Self-propagation speeds of flame, ignition temperature, reaction temperature, weight loss and contraction rate of each SHS reaction were investigated. The pattern and component of product were analyzed by SEM and XRD, which indicated that the rhombohedral La0.7Sr0.3MnO3 was prepared by each SHS reaction. Because of the low cost, simple operation and preferable performance of product, the No.1 system was the best reaction system for preparing LSM by SHS.Based on No.1 system, the effect of some parameters, such as forming pressure and dilution addition, on reaction process and physical performance of the product was studied. And the sintering performance of the LSM, including intensity, relative density, porosity, expansion coefficient and conductivity was investigated as well.The reaction mechanism of the SHS system was explored through thermodynamic calculation method. The directions and products of the reaction in different technological conditions were decided. Meanwhile, the cause of impurity of the reaction system was analyzed and some advices were brought forward to eliminate the byproducts.Finally, the study indicated that the impurity brought by SHS could be removed effective, through the heat treatment method. The organizational structure and performance of LSM, on which the different temperature and time of heat treatment effected, were also studied.