Investigation of protonic conduction in Yb- and Y-doped barium zirconates

Abstract

Barium zirconate ceramics doped with Y and Yb, BaM x Zr 1 − x O 3 − α (M = Yb, Y), are perovskite single phases and exhibit protonic conduction in moist nitrogen atmospheres at temperatures 500 < T (°C) < 1000. Samples with x = 0.10 have been investigated by ac and dc electrochemical techniques. Conductivities with Yb as dopant were larger, by a factor ≈ 10, than those with Y as dopant. Conductivities for Yb-doped samples (e.g. σ b (750 °C) ≈ 2 × 10 − 4 S cm −1) are lower than those reported for analogous cerates. Throughout the experimental temperature range, the apparent conductivity found in dc studies (summing resistances due to the electrolyte and electrode-electrolyte interfacial phenomena) was lower, by a temperature independent factor ≈ 2, than the conductivity determined by ac techniques.