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 compo sition La0.3Sr0.7CoO3 chosen in this study) are difficult to prepare u sing usual synthesis processes. This report presents an aqueous sol-ge l route using metal acetates as precursors to achieve this goal. Hydro gen peroxide and ammonia are added to the acetates precursor solution to obtain stable sol and xerogel, as well as a homogeneous powder afte r 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 degrees C. Single phase of cubic perovskite La0.3Sr0.7CoO3 ca n be obtained after treatment at above 1000 degrees C. Sintering the c old pressed green compact at above 1100 degrees C may result in gas-ti ght samples. It is found that the sintering temperature has a minor in fluence on the oxygen permeability of a gas-tight membrane.