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The total, bulk, and grain boundary conductivities of proton-conducting zirconates of general formula AZr_0.95Sc_0.05O_3 – α (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°C) and impedance spectroscopy (30–800°C). The impact of humid atmosphere on the total, bulk, and grain boundary conductivities of the AZS system is studied at different humidity levels: $${{p}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}}$$ = 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.

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The effect of the sintering additive Al2O3 on the electrical conductivity of a polycrystalline proton electrolyte based on calcium zirconate, CaZr0.95Sc0.05O3-δ (CZS) was studied. It is shown that the introduction of the sintering additive Al2O3 makes it possible to obtain dense ceramics by the combustion method at a relatively low temperature (1470 ° С). The introduction of 0.1–0.5 wt% Al2O3 leads to an increase in the grain size of ceramics from 100 nm to 1-2 μm. Al2O3 additives up to 0.3 wt% increase the electrolyte conductivity. It has been established that with the introduction of Al2O3, calcium aluminates are formed at the grain boundaries. The proton character of charge transfer was revealed both in the volume of grains and at the grain boundaries of the electrolyte in humid air.