###### Abstract  
This paper demonstrates the possibility of creating oxygen deficiency in perovskites A\({}^{+3}\)B\({}^{+3}\)O\({}_{3}\) by introducing two types of cations with different charges into the B-sublattice. For this, it is proposed to introduce a two-charged cation, for example, Zn\({}^{2+}\), as an alternative to alkaline earth metals. Previously, this possibility was demonstrated for aluminate LaAlO\({}_{3}\) and indate LaInO\({}_{3}\). In this article, we have focused on the modification of the scandium-containing perovskite LaScO\({}_{3}\). The novel oxygen-deficient perovskite La\({}_{2}\)ScZnO\({}_{5.5}\) and doped phases La\({}_{1.9}\)Ca\({}_{0.15}\)ScZnO\({}_{5.8}\), La\({}_{2}\)Sc\({}_{0.9}\)Ca\({}_{0.12}\)ZnO\({}_{5.85}\), and La\({}_{2}\)Sc\({}_{0.9}\)Mg\({}_{0.12}\)ZnO\({}_{5.85}\) were obtained via a solid-state reaction process. Their phase composition and hydration were investigated by XRD and TGA + MS techniques. The conductivities of these materials were measured by the electrochemical impedance technique under atmospheres of various water vapor partial pressures. All phases crystallized in orthorhombic symmetry with the _Pnma_ space group. The phases were capable of reversible water uptake; the proton concentration increased in the order of La\({}_{2}\)ScZnO\({}_{5.5}<\) La\({}_{2}\)Sc\({}_{0.9}\)Mg\({}_{0.12}\)ZnO\({}_{5.45}<\) La\({}_{2}\)Sc\({}_{0.9}\)Ca\({}_{0.12}\)ZnO\({}_{5.45}\approx\) La\({}_{1.9}\)Ca\({}_{0.15}\)ScZnO\({}_{5.45}\) and reduced -90% hydration limit for Ca\({}^{2+}\)-doped phases. The total conductivities increased with the increase in the lattice volume in the sequence of La\({}_{2}\)ScZnO\({}_{5.5}<\) La\({}_{2}\)Sc\({}_{0.9}\)Mg\({}_{0.12}\)ZnO\({}_{5.85}<\) La\({}_{1.9}\)Ca\({}_{0.15}\)ScZnO\({}_{5.85}<\) La\({}_{2}\)Sc\({}_{0.9}\)Ca\({}_{0.12}\)ZnO\({}_{5.45}\), the ratio energy decreased in the sequence. The sample La\({}_{2}\)Sc\({}_{0.9}\)Ca\({}_{0.12}\)ZnO\({}_{5.45}\) showed the highest conductivity of about 10\({}^{-3}\) S\(\cdot\)cm\({}^{-1}\) at 650 \({}^{\circ}\)C (dry air pH\({}_{2}\)O = 3.5\({}^{-1}\)\({}^{-5}\) atm). Water incorporation was accompanied by an increase in conductivity in wet air (pH\({}_{2}\)O = 2:10\({}^{-2}\) atm) due to the appearance of proton conductivity. The sample La\({}_{2}\)Sc\({}_{0.9}\)Ca\({}_{0.12}\)ZnO\({}_{5.45}\) showed a conductivity of about 10\({}^{-5}\) S\(\cdot\)cm\({}^{-1}\) at 350 \({}^{\circ}\)C (pH\({}_{2}\)O = 2:10\({}^{-2}\) atm). A comparison of conductivities of obtained phase La\({}_{2}\)ScZnO\({}_{5.5}\) with the conductivities of La\({}_{2}\)AlZnO\({}_{5.5}\) and La\({}_{2}\)InZnO\({}_{5.5}\) was made; the nature of the B-cation did not significantly affect the total conductivity. perovskite; acceptor doping; conductivity; water uptake; proton transport +
Footnote †: journal: Applied Sciences  
In order to improve the working parameters of SOFCs and to lower their operating temperature [6], materials science research is developing intensively; nevertheless, the compounds with perovskite or perovskite-related structures remain the most widely studied objects [7]. These compounds can exhibit high ion (O\({}^{2-}\) or H\({}^{+}\)) conductivity since they can adapt to an oxygen-deficient ABO\({}_{3-\delta}\). The presence of oxygen vacancies is a result of acceptor doping (charged vacancies \(V_{\rm o}^{\bullet\bullet}\)) or the presence of coordinatively unsaturated polyhedra (non-charged structural vacancies \(V_{\rm o}^{\times}\)). In general, a low acceptor doping level (due to the limited solubility of the dopant) allows the creation of low oxygen vacancy concentrations that are randomly distributed, e.g., BaZr\({}_{1-x}\)Y\({}_{x}\)O\({}_{3-\delta}\)[8]. Higher oxygen deficiency can be specified when organizing multi-sublattice structures (usually two sublattices of B and B\({}^{\prime}\)) with proper combinations of oxidation states, e.g., Ba\({}_{4}\)Ca\({}_{2}\)Nb\({}_{2}\)O\({}_{11}\)[9]. In this case, oxygen-deficient perovskites with ordered (or disordered) structures can be formed.