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—La0.9Sr0.1In1 – xCaxO2.95 – 0.5x and La0.9Sr0.1In1 – yMgyO2.95 – 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 La0.9Sr0.1In0.95Ca0.05O2.925 and La0.9Sr0.1In0.9Ca0.1O2.9. The introduction of the Mg2+ co-dopant into the In3+ sites leads to a decrease in ionic electrical conductivity compared to La0.9Sr0.1InO2.95. The effects of changes in oxygen mobility with changes in geometric factors (cell volume, critical radius) are considered.