Synthesis of gadolinium-doped ceria by gelation/co-precipitation with urea

Gadolinium-doped ceria, with Gd content equal to 10% and 20%, was synthesized by using urea gelation/co-precipitation method (UGC). After the co-precipitation induced by heating the solution at about 100 °C, the co-precipitate was aged in boiling water under vigorous stirring for 4 h. Thus a carbonate-based phase is formed, but with a simple calcination step at low temperature, i.e. 400°C, a single phase fluorite structure is obtained. After the calcinations step, the powders were still of nanometer size with a good sinterability. In fact, a full densification for both the samples has been obtained with a firing at 1400°C.