Processing of dense La0.2Sr0.8Fe0.8Cr0.2O3-delta oxygen membranes

The effects of processing parameters on the microstructure and performance of La0.8Sr0.2Fe0.8Cr0.2O3-delta processed by uni-axial and cold isostatic p ressing followed by sintering have been studied. The sintering strain obtai ned from dilatometry measurements reveals negligible contraction below 1250 K and the commencement of rapid sintering above this temperature. The opti mum sintering temperature with respect to density is 1523 K, resulting in 9 8.9% of the theoretical density. The decrease in density below this tempera ture is found to be due to open pore development resulting from slower sint ering kinetics. Above the optimum temperature. the decrease in density is f ound to be caused by the close pore development during oxygen desorption. T he dependence of the square of grain size on time is nonlinear with the tim e exponent equal to 0.7. indicating that there is a contribution to grain g rowth apart from surface free energy that retards the growth rate. The depe ndence of electrical conductivity on the inverse of absolute temperature ex hibits a typical two-region dependence, reaching the maximum of 103 s cm (- 1) at 805 K. (C) 2001 Elsevier Science B.V. All rights reserved.