Ion conductivity of perovskites CaZr1 – x Sc x O3 – α (x = 0.03–0.20) in hydrogen-containing atmospheres

Abstract

The total, proton, and oxygen conductivities in the CaZr1–x Sc x O3–α system (x = 0.03–0.20) were studied experimentally in the reductive atmospheres H2 + H2O + N2 in the temperature range 600–900°C. The electric conductivity and the transport numbers of ions and protons were measured using the direct current four-probe method and the EMF method with oxygen and water vapor concentration cells, respectively. The materials under study are pure proton-conductive below 700°C in these atmospheres; at higher temperatures, a pronounced contribution of oxygen conductivity appears. The isotherms of the total and partial conductivities are symbatic and have a maximum between x = 0.05 and x = 0.10, which correlates with the position of the boundary of the single-phase state.