Physicochemical Properties and Structure Peculiarities of Proton-Conducting Perovskites La0.9Sr0.1Sc1–хFexO3–δ (х = 0.003–0.47)

Abstract

Single-phase solid solutions based on proton-conducting oxide La_0.9Sr_0.1ScO_3–δ (LSS) and containing from 0 to 47 at % Fe in the scandium sublattice are synthesized by the method of combustion with ethylene glycol at 1400°C. Their electric conductivity, thermal expansion, and parameters of orthorhombic lattice are studied. Anomalies in the temperature dependences of conductivity and thermal expansion associated with dissolution of water vapor in the oxides are observed, as well as the breaks in concentration dependences of orthorhombic lattice parameters in the region of low iron contents. The introduction of even small amounts of iron oxide (up to 3 at % Fe) into LSS leads to disappearance of protonic conductivity. The factors responsible for the appearance of defective structure and its model explaining this phenomenon are discussed.