Application of gelcasting process in ceria membranes formation

Lanthanides doped ceria is one of the most promising materials for intermediate temperature solid oxide fuel cells, which may operate below 700 °C. There are many studies focused mainly on finding the optimal dopant and its proper concentration. The optimized material should be later formed into a thin, strong, durable and gas-proof membrane. Durable and strong ceramics, in almost of any shape, may be obtained by a gelcasting process. On the other hand, application of nanocrystalline powders leads to lowering the sintering temperature what may result in better process control. In the present study the gelcasting process was applied to formation of ceria membranes from nanopowders derived from a reverse microemulsion technique as well as from commercial microcrystalline powders. It was found that morphology of the starting powders, characterized by N2-BET (low temperature nitrogen adsorption) and DLS (dynamic light scattering) methods, was a key-parameter influencing the membrane properties formed in the gelcasting process. The sintering process of the obtained nanopowders was studied by a dilatometry method. The morphology of the obtained membranes was characterized by SEM (scanning electron microscopy) and AFM (atomic force microscopy) techniques. It was found that using the nanopowders the nonporous ceria membranes can be obtained in the gelcasting process after sintering in relatively low temperatures 900–1100 °C.