Impact of humidity on charge transport in proton-conducting perovskites $A$Zr$_{0.95}$Sc$_{0.05}$O$_{3-\alpha}$ ($A$ = Ca, Sr, Ba) exposed to an oxidative atmosphere

The total, bulk, and grain boundary conductivities of proton-conducting zirconates of general formula $A$Zr$_{0.95}$Sc$_{0.05}$O$_{3-\alpha}$ (AZS), where $A$ = Ca, Sr, Ba, are measured in air with different humidity levels. The conductivity is measured using the four-probe dc method (600–900$^{\circ}$C) and impedance spectroscopy (30–800$^{\circ}$C). The impact of humid atmosphere on the total, bulk, and grain boundary conductivities of the AZS system is studied at different humidity levels: (рН$_{2}$О = 0.04, 0.61, and 2.5 kPa. Humidity is found to have a considerable effect on the conductivity of our CaZS and BaZS at lower temperatures, suggesting the likelihood of hydronium ion-mediated transport.