Crystal structure, thermochemical stability, electrical and magnetic properties of the two-phase composites in the La0.8Sr0.2MnO3 ± δ–CeO2 system

Crystal structure, thermochemical stability, transport and magnetic properties of compositions in the (100-x) La0.8Sr0.2MnO3 ± δ xCeO2 (LSMC) system were studied. All compositions in the LSMC series containing more than 2 mol% CeO2 were two phase and consisted of the modified perovskite constituent with rhombohedral structure (R3̄c) and ceria as a secondary phase with cubic structure (Fm3̄m). The presence of both Ce4+and Ce3+ cations in LSMC compositions was revealed by X-ray Photoelectron Spectroscopy (XPS). CeO2 and compositions in the LSMC series showed good thermochemical stability in air and argon. However, in H2–Ar atmosphere all LSMC compositions underwent reduction followed by decomposition. Transport and magnetic properties change in a non-linear way with the increase in the CeO2 content. The LSMC2 composition showed enhanced electronic conductivity and magnetic characteristics. Metallic type conductivity was observed for LSMC compositions with x ≤ 36 mol% CeO2 in a narrow temperature range of 770–900 °C. A small degree of substitution of Ce into LSM was found to change structural, magnetic and electrical properties.