Preparation, chemical stability, and electrical properties of Ba(Ce1-xBix)O3 (x=0.0-0.5)

Solid solutions of the form Ba(Ce1-xBix)O-3 (x = 0.0-0.5) have been prepared by a modified Pechini method at 800 degreesC in air. XRD results indicate that all the samples have orthorhombic symmetry. Ba(Ce1-xBix)O-3 shows no reaction with Ce0.9Gd0.1O2, even when sintered at 1100 degreesC, but totally decomposes when mixed with yttria-stabilized zirconia (8% Y2O3) and sintered at 900 degreesC in air. Compared to BaCeO3, the chemical stability of bismuth-doped samples was improved in the presence of moisture. Bismuth substitution for cerium increases the total and electron conductivities. The total conductivity for BaCe0.5Bi0.5O3 is 0.1 S cm(-1) at 600 degreesC in air. Under oxidizing atmospheres, all the samples show p-type conducting properties, whereas in wet argon, the samples show both proton and electron conduction below 600 degreesC. The proton conduction decreased dramatically with increasing Bi content due to the compensation for oxygen vacancies by [Bi-Ce.] formed in the lattice. Ba(Ce1-xBix)O-3 exhibits a small cathodic overpotential, 70 mV at 800 degreesC in air at a current density of 100 mA cm(-2).