Synthesis and electrical properties of Ce1-xGdxO2-x/2 (x=0.05-0.3) solid solutions prepared by a citrate-nitrate combustion method

Ce1-xGdxO2-x/2 (GDC) powders with different Gd3+ contents (x = 0.05-0.3) were prepared by a simple citrate nitrate combustion method. The influence of the Gd3+ doping content on the crystal structure and the electrical properties of GDC were examined. Many analysis techniques such as thermal analysis, X-ray diffraction, nitrogen adsorption analysis, scanning electron microscopy and AC impedance analysis were employed to characterize the GDC powders. The crystallization of the GDC solid solution occurred below 350 degrees C. The GDC powders calcined at 800 degrees C showed a typical cubic fluorite structure. The lattice parameter of GDC exhibited a linear relationship with the Gd3+ content. As compared with that sintered at other temperatures, the GDC pellet that sintered at 1300 degrees C had a high relative density of 97%, and showed finer microstructure. The conductivity of GDC was firstly increased and then decreased with the increase of the Gd3+ content. The sintered GDC sample with the Gd3+ content of 0.25 exhibited the highest conductivity of 1.27 x 10(-2) S cm(-1) at 600 degrees C. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.