Effect of strontium ion doping on structural, thermal, morphological and electrical properties of a co-doped lanthanum manganite system

An effect of strontium ion doping on the structural, thermal, morphological and electrical properties of a co-doped lanthanum manganite system, La1−xSrx Mn0.85Fe0.05Co0.05Ni0.05O3+δ (x = 0–0.4 mole) is investigated for the solid oxide fuel cell cathode application. The submicron and rhombohedral structured sample, synthesized by the Pechini method, exhibited a decrease in the unit cell volume with increasing x. The thermogravimetry study portrayed nearly fivefold weight loss for a sample with x = 0.3 mole relative to the La0.75Sr0.25MnO3+δ and suggested an improvement in the concentration of the oxygen vacancy for ion migration due to the co-doping effect. It also showed sufficiently high electrical conductivity (∼76 S cm−1) at 650 °C along with a low activation energy (∼0.15 eV), a comparable coefficient of thermal expansion (∼12.1 × 10−6 °C−1) and a chemical compatibility with the solid electrolytes. The results were explained using the defect models.