Preparation And Characterization Of Nano-sized LSM Powder And Ceramics

Solid oxide fuel cell (SOFC) is an energy conversion device that produces electricity directly from fossil fuels by electrochemical reactions. Currently, SOFC has been extensively explored due to its advantages such as higher energy conversion efficiency, no pollution and all solid structure. There are several factors to limit performance of SOFC. Cathodic material is one of the important parts in the SOFC. Lao.8Sr0.2MnO3(LSM) is the most developmental prospect cathodic material of SOFC. So the study on the LSM preparation technology is very important. In this dissertation, powder of LSM was prepared using the method of solid state sintering, solid high temperature ball milling, sol-gel and sol-gel high temperature ball milling. The results are as below:(1) The LSM ceramic powder was prepared by solid state sintering and high temperature ball milling method. The influences of milling parameters (mass ratio between milling ball and raw materials, milling temperature) on the structure and morphology of powder were investigated. The results indicated that the powder calcined for2h at1200℃had a lot of impurity. However, using the method of solid high temperature ball milling with mass ratio of30:1between milling ball and raw matierials at750℃for2h, the obtained LSM powder was pure perovskite structure.The image of SEM showed that the powder prepared by solid calcining had a serious agglomeration, the particle size was in micron scale. Neverthelss, the powder prepared with high temperature ball milling have a small particle size, and the sizes of powder were50nm-150nm.(2) The powder of LSM was prepared using the method of sol-gel and sol-gel high temperature ball milling. The effect of milling temperature on the structrue of powder was studied. The results showed that the powder calcined for2h at1200℃by sol-gel method had a little impurity. using the method of sol-gel high temperature ball milling at600℃, the powder milled was the pure perovskite structure. The image of SEM demonstrated that the powder obtained by sol-gel method had a larger particle size, and the uniformity was good. However, the powder prepared by sol-gel high temperature ball milling had a small particle size, and the most powder were50nm-150nm. (3) The conductivity of the powder was measured by4-point method. Results showed that the technology of ball milling is very effective for increace the conductivity of the powders. The conductivity of the powders prepared at600℃by sol-gel high temperature ball milling was highest. The conductivity at800℃was36s·cm-1...