Preparation, chemical stability, and electrical properties of Ba(Ce1 − xBix)O3 (x= 0.0-0.5)
Abstract
Solid solutions of the form Ba(Ce1 − xBix)O3 (x = 0.0-0.5) have been prepared by a modified Pechini method at 800 °C in air. XRD results indicate that all the samples have orthorhombic symmetry. Ba(Ce1 − xBix)O3 shows no reaction with Ce0.9Gd0.1O2, even when sintered at 1100 °C, but totally decomposes when mixed with yttria-stabilized zirconia (8% Y2O3) and sintered at 900 °C 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 °C 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 °C. The proton conduction decreased dramatically with increasing Bi content due to the compensation for oxygen vacancies by [BiCe˙] formed in the lattice. Ba(Ce1 − xBix)O3 exhibits a small cathodic overpotential, 70 mV at 800 °C in air at a current density of 100 mA cm−2.