The influence of Ba-site non-stoichiometry on the phase composition, sinterability, conductivity and chemical stability of BaxZr0.6Hf0.2Y0.2O3-δ (0.9≤x≤1.03) proton conductors

Abstract

Perovskite proton conductors BaxZr0.6Hf0.2Y0.2O3-δ (x = 0.9–1.03) were successfully prepared by high temperature solid state method. The influences of Ba-site non-stoichiometric on the phase composition, sinterability, chemical stability and conductivity of the samples were studied systematically. Ba excess can effectively enhance the sinterability of the samples, and promote the densification and grain growth of the samples. X-ray diffraction patterns display that all the samples have a single phase of cubic perovskite-type oxides. Ba1.03Zr0.6Hf0.2Y0.2O3-δ is easily sintered and reaches a relative density above 98.51% at 1600 °C due to Ba-excessive. The grain size and electrical conductivity of the samples increases with the increase in Ba content from x = 0.9 to 1.03. The grain size of Ba1.03Zr0.6Hf0.2Y0.2O3-δ sample is about 2 μm, and the total conductivity is 1.25 × 10−2 S cm−1 in 700 °C in wet air. All the samples display excellent chemical stability in H2, H2S, CO2, water vapor and boiling water, and the Ba-deficient sample was more excellent over Ba-excessive sample.