Sulfur and carbon tolerance of BaCeO3–BaZrO3 proton-conducting materials

Abstract

In the present work, BaCe0.8−xZrxY0.2O3−δ-based ceramic samples (BCZYx) are prepared and their chemical stability in corrosive atmospheres containing high concentrations of H2O, CO2 and H2S is investigated. Based on both the fresh (not exposed) and the treated (exposed to corrosive atmospheres) samples, the estimation of the tolerance degree is obtained by determining the: i) phase structures, ii) unit cell parameters, iii) surface microstructures, and iv) electrical conductivities. Fresh ceramics is found to be single-phased in the whole range of x. It is also found that all the treated materials exhibit good chemical stability in the water vapor atmosphere, whereas the samples with 0 ≤ x ≤ 0.2 and 0 ≤ x ≤ 0.3 are not single-phased in pure CO2 and 10% H2S/Ar, respectively. The analysis of crystal structure and transport characteristics of the treated BCZY0.3 samples is shown a weak deviation of unit cell parameters and no degradation in electrical conductivity. For fresh BCZY0.3 the transport nature in various atmospheres is evaluated. At 600 °C the BCZY0.3 exhibits conductivity of 2.7, 4.0, 1.7 and 3.7 mS cm−1 in air, wet air, hydrogen and wet hydrogen atmospheres, respectively. Based on the obtained results, BCZY0.3 can be considered as a perspective proton-conducting material having reasonable transport and tolerance properties.