Electrical Conductivity Improvement of Nd2Ce2O7 Ceramic Co-doped with Gd2O3 and ZrO2

(Nd1-xGdx)(2)(Ce1-xZrx)(2)O-7 (0 <= x <= 0.5) ceramic powders synthesised by the chemical-coprecipitation and calcination method were pressureless-sintered at 1,973 K for 10 h in air. The structure and electrical conductivity of (Nd1-xGdx)(2)(Ce1-xZrx)(2)O-7 ceramics were investigated by the X-ray diffraction and impedance spectroscopy measurements. (Nd1-xGdx)(2)(Ce1-xZrx)(2)O-7 (0 <= x <= 0.5) ceramics exhibit a single phase of defect fluorite-type structure. The electrical conductivity of (Nd1-xGdx)(2)(Ce1-xZrx)(2)O-7 ceramics increases with temperature in the range 623-1,173 K following an Arrhenius law. At identical temperature levels, the measured electrical conductivity of (Nd1-xGdx)(2)(Ce1-xZrx)(2)O-7 ceramics varies with doping different Gd2O3 and ZrO2 contents and exhibits a maximum at x = 0.1.