Protonic ceramics Ba5In2–xYxAl2ZrO13 with the perovskite-related hexagonal structure for solid oxide fuel cells: Synthesis, optical band gap and transport properties

Abstract

The solid solution Ba5In2–xYxAl2ZrO13 (0 ≤ х≤0.50) with hexagonal structure (space group P63/mmc) was prepared by the solid-state reaction method. The effects of isovalent Y3+-substitution on the structure, hydration, bandgap and transport properties have been investigated. The introduction of yttrium was accompanied by lattice expansion, which led to an increase in the concentration of protons during hydration. The doping did not lead to a significant increase in oxygen-ion conductivity since there was no change in oxygen stoichiometry. At the same time, doping led to an increase in ionic transport numbers due to a decrease in hole conductivity. Proton conductivity contribution and the values of proton conductivity increase with the increase in yttrium concentration. The phases with yttrium content x > 0.2 were predominant proton conductors at the temperature below 600°С under wet air.