Sintering of gadolinia-doped ceria prepared by mechanochemical synthesis

Gadolinia-doped ceria (GDC) ceramics were prepared by mechanochemical synthesis of ceria and gadolinia (10 mol.%) powders with subsequent uniaxial pressing and pressureless sintering. The mechanochemical synthesis was conducted in an attritor with different dispersion media: neutral (distilled water), basic (aqueous solution of ammonia), acidic (aqueous solution of propionic acid), and non-polar medium (xylene with stearic acid). The effect of suspension composition and attritor milling time on the sintering behaviour and ionic conductivity of GDC was studied. An attritor milling time of 3–6 h was evaluated as the optimum milling time from the viewpoint of further sintering behaviour. Longer milling times resulted in nanometre-sized powders, whose sintering behaviour deteriorated due to powder agglomeration. The appearance of agglomerates in the non-polar medium was reduced. The ionic conductivity of the samples was evaluated by impedance spectroscopy and correlated with their microstructure.