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

Abstract

Solid solutions of the form Ba(Ce_1 − xBi_x)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(Ce_1 − xBi_x)O₃ shows no reaction with Ce_0.9Gd_0.1O₂, 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 BaCe_0.5Bi_0.5O₃ 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 [Bi_Ce˙] formed in the lattice. Ba(Ce_1 − xBi_x)O₃ exhibits a small cathodic overpotential, 70 mV at 800 °C in air at a current density of 100 mA cm⁻².