Preparation of gas-tight strontium-doped lanthanum cobaltate by an aqueous sol-gel process

Gas-tight dense membranes of highly Sr-doped LaCoO3 (such as the composition La0.3Sr0.7CoO3 chosen in this study) are difficult to prepare using usual synthesis processes. This report presents an aqueous sol-gel route using metal acetates as precursors to achieve this goal. Hydrogen peroxide and ammonia are added to the acetates precursor solution to obtain stable sol and xerogel, as well as a homogeneous powder after heat treatment. Thermal analysis and XRD show the presence of SrCO3 and La2O3 when the heat treatment temperature of the xerogel is lower than 950 °C. Single phase of cubic perovskite La0.3Sr0.7CoO3 can be obtained after treatment at above 1000 °C. Sintering the cold pressed green compact at above 1100 °C may result in gas-tight samples. It is found that the sintering temperature has a minor influence on the oxygen permeability of a gas-tight membrane.