Densification and Proton Conductivity of La_1-xBa_xScO_3-δ Electrolyte Membranes

Bain La_1-xBa_xScO_3-δ impairs sintering and leads to a decrease in its ceramic density. Two approaches have been studied for obtaining dense ceramics: using a high processing temperature and the introduction of a Co₃O₄ sintering additive. An addition of only 0.5 wt% of Co₃O₄ sintering additive, despite the positive sintering effect, causes a noticeable violation of stoichiometry, with partial decomposition of the material. This can lead to the formation of cationic vacancies, which form associates with oxygen vacancies and significantly reduce the oxygen ion and proton conductivity of the materials. There is also a partial substitution of Co for Sc in La_1-xBa_xScO_3-δ, which reduces the stability of protons: it reduces the enthalpy of the hydration reaction, but increases the mobility of protons. Thus, the Co₃O₄ sintering additive causes a complex of negative effects on the conductivity of La_1-xBa_xScO_3-δ materials. Only high-temperature (1800 °C) processing with protection against Ba loss contributes to the production of dense La_1-xBa_xScO_3-δ ceramics. The chemical composition of such ceramics corresponds well to the specified one, which ensures high water uptake and, consequently, high proton conductivity.