Effect of bismuth addition on the electrical conductivity of gadolinium-doped ceria ceramics

The structure, thermal expansion and electrical conductivity of Ce-0.8(Gd1-xBix)(0.2)O-1.9 (x= 0.1-0.5), prepared by coprecipitation were investigated. Ce-0.8(Gd1-xBix)(0.2)O-1.9 ceramics was sintered in the range of 1350-1450 degrees C for 6 h; the bulk density of Ce-0.8(Gd1-xBix)(0.2)O-1.9 ceramics was over 95% of the theoretical density; the maximum electrical conductivity, sigma(800 degrees C) = 0.078 S/cm with minimum activation energy, E-a = 0.638 eV was found for the Ce-0.8(Gd0.5Bi0.5)(0.2)O-1.90 ceramic. The gadolinium-doped ceria ceramics preparation by coprecipitation can reduce the sintering temperature by addition of bismuth. The thermal expansion coefficient of Ce0.8(Gd1-xBix)(0.2)O-1.9 covers the range of 20.132-20.478 ppm/degrees C. The ceramic has a fracture toughness in the range of 1.28-2.60 MPam(1/2) for dense Ce-0.8(Gd1-x Bi-x)(0.2)O-1.9 ceramics. The value of fracture toughness increased with Bi content. It indicated that the mechanical properties of gadolinium-doped ceria ceramics could be improved by addition of bismuth. (c) 2007 Published by Elsevier Ltd.