Hydrothermal synthesis and properties of Ce1−xGdxO2−δ solid solutions

The structure, ionic and electronic conductivities of Ce1−xGdxO2−δ (x=0–0.30) solid solutions, prepared in a wide substitutional range for the first time hydrothermally, were investigated. The uniformly small particle size (41–68 nm) of the hydrothermally prepared materials allows sintering of the samples into highly dense ceramic pellets at 1300–1400°C, a significantly lower temperature than 1600–1650°C, which is required for ceria solid electrolytes prepared by solid state techniques. The solubility limit of Gd2O3 in CeO2 was determined to be over 30 mol%. The maximum conductivity, σ600°C∼7.53×10−3 Scm−1 with Ea=0.58 eV, was found at x=0.25.