Processing of dense La0.2Sr0.8Fe0.8Cr0.2O3−δ oxygen membranes

The effects of processing parameters on the microstructure and performance of La0.8Sr0.2Fe0.8Cr0.2O3−δ processed by uni-axial and cold isostatic pressing followed by sintering have been studied. The sintering strain obtained from dilatometry measurements reveals negligible contraction below 1250 K and the commencement of rapid sintering above this temperature. The optimum sintering temperature with respect to density is 1523 K, resulting in 98.9% of the theoretical density. The decrease in density below this temperature is found to be due to open pore development resulting from slower sintering kinetics. Above the optimum temperature, the decrease in density is found to be caused by the close pore development during oxygen desorption. The dependence of the square of grain size on time is nonlinear with the time exponent equal to 0.7, indicating that there is a contribution to grain growth apart from surface free energy that retards the growth rate. The dependence of electrical conductivity on the inverse of absolute temperature exhibits a typical two-region dependence, reaching the maximum of 103 s cm−1 at 805 K.