Impact of the Sintering Additive Al2O3 on the Electrical Conductivity of Proton-Conducting Electrolyte CaZr0.95Sc0.05O3 – δ

Abstract

The impact of sintering additive Al₂O₃ on the electrical conductivity of calcium zirconate-based polycrystalline proton-conducting electrolyte CaZr_0.95Sc_0.05O_3 – δ (CZS) is studied. With the sintering additive Al₂O₃, ceramic samples synthesized by a combustion technique are denser, and relatively low synthesis temperatures can be used (1470°C). Adding 0.1–0.5 wt % Al₂O₃ leads to an increase in the grain size from 100 nm to 1–2 μm. Increasing the Al₂O₃ content up to 0.3 wt % favors a growth in the electrolyte conductivity. For samples containing Al₂O₃, calcium aluminates are detected at grain boundaries. In samples exposed to humid air, charge transfer both in the grain bulk and at intergrain boundaries is found to be mediated by protons.