Lowering the sintering temperature of Gd-doped ceria by mechanochemical activation

Two kinds of Ce0.8Gd0.2O2−δ pellets were synthesized by a solid-state reaction using two types of commercial CeO2 and Gd2O3. In contrast to previous reports, pellets with a sintered density of 99% at 1300 °C were obtained regardless the powder used. Mechanochemical activation of the starting materials by 7 h of high energy milling, which resulted in particles several tens of nanometer in size, was effective in reducing the sintering temperature. Ce0.8Gd0.2O2−δ pellets could be synthesized by direct sintering without calcination due to the homogeneous distribution of fine starting materials. The final phase was confirmed by the ionic conductivity, X-ray diffraction patterns and lattice parameters.