The effect of sintering additive Al$_{2}$O$_{3}$ on the electrical conductivity of the proton electrolyte CaZr$_{0.95}$Sc$_{0.05}$O$_{3-\delta}$

The effect of the sintering additive Al$_{2}$O$_{3}$ on the electrical conductivity of a polycrystalline proton electrolyte based on calcium zirconate, CaZr$_{0.95}$Sc$_{0.05}$O$_{3-\delta}$(CZS) was studied. It is shown that the introduction of the sintering additive Al$_{2}$O$_{3}$ makes it possible to obtain dense ceramics by the combustion method at a relatively low temperature (1470$^{\circ}$С). The introduction of 0.1–0.5 wt% Al$_{2}$O$_{3}$ leads to an increase in the grain size of ceramics from 100 nm to 1–2 $\mu$m. Al$_{2}$O$_{3}$ additives up to 0.3 wt% increase the electrolyte conductivity. It has been established that with the introduction of Al$_{2}$O$_{3}$, 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.