Study of the Electrophysical Properties of Solid Solutions with a Perovskite Structure in La2O3–SrO–Ni(Co,Fe)2O3–δ Systems for Cathode Electrodes for Fuel Cells

Finely dispersed mesoporous powders of the following composition are synthesized by the method of cocrystallization of nitrate salts with ultrasonic treatment: La_1–xSr_xNiO_3–δ, La_1–xSr_xCoO_3–δ, and La_1–xSr_xFe_0.7Ni_0.3O_3–δ (x = 0.30; 0.40). Based on them, ceramic nanomaterials of the given composition with a coherent scattering region (CSR) of ~65–69 nm (1300°С) are obtained. Ceramics fired at 1300°C are single-phase and have a tetragonal and orthorhombic perovskite-type structure in the La₂O₃‒SrO‒Ni(Co,Fe)₂O_3–δ system. Solid solutions have mixed electron–ion conductivity with transfer numbers t_e = 0.98–0.90 and t_i = 0.02–0.10. Ceramics with a tetragonal perovskite-type crystal structure exhibit higher electrical conductivity than materials having an orthorhombic perovskite-type crystal structure. According to their electrophysical properties related to the structural features of solid solutions, ceramic materials obtained based on them are promising as solid oxide cathodes for average-temperature fuel cells.