The Effect of Grain Size and Grain Boundary Microstructure on the Oxygen Permeation of Perovskite-type Membranes

摘要

The effect of grain size distribution in perovskitetype ceramics on the oxygen permeation behaviour has been investigated by changes of calcination temperature in powder production and sintering time for the ceramics. Decreasing calcination temperature in perovskite powder synthesis delivers fine powders in the nanometer range and smaller grains in the ceramic. We found that grain size distribution in sintered membranes is not constant through membranes since grains in the bulk are smaller compared to those at the surface. With big differences in size, an edge area is observed, where the size differences have to be balanced and which is not favorable for the oxygen permeation of the ceramics. Supplementary, the dwell time during sintering has influence on the microstructure of the ceramic. The longer the dwell time, the further proceeds the grain coarsening, which affects the oxygen permeation in a positive way.