Electrical Properties of Co-doped LaInO₃ Perovskite

Co-doped LaInO₃-based materials have been studied. Strontium-sustituted solid solutions have high conductivity values but exhibit a low level of oxygen deficiency. Mg²⁺ and Ca²⁺ ions have been selected as the B-sublattice co-dopant. Both series of the solid solutions—La_0.9Sr_0.1In_{1 – x}Ca_xO_{2.95 – 0.5x} and La_0.9Sr_0.1In_{1 – y}Mg_yO_{2.95 – 0.5y}—crystallize in orthorhombic symmetry with space group Pnma. Ionic conductivity in a dry atmosphere is determined by the transport of oxygen ions. Oxygen-ion transport in solid solutions is ~30–40% at high temperatures (T > 700°C) and increases to >80% when the temperature decreases to 400–300°C. The substitution of In³⁺ by Ca²⁺ makes it possible to increase the oxygen-ion electrical conductivity; the highest values are achieved for the compositions La_0.9Sr_0.1In_0.95Ca_0.05O_2.925 and La_0.9Sr_0.1In_0.9Ca_0.1O_2.9. The introduction of the Mg²⁺ co-dopant into the In³⁺ sites leads to a decrease in ionic electrical conductivity compared to La_0.9Sr_0.1InO_2.95. The effects of changes in oxygen mobility with changes in geometric factors (cell volume, critical radius) are considered.