Synthesis and characterization of LaMn0.5Fe0.5+xO3±δ (x = 0–0.3) perovskite-type solid solutions. Part 1: Phase formation, microstructure, and Fe2O3 surface exsolution
摘要
Perovskite-type solid solutions of LaMn0.5Fe0.5+xO3±δ (x = 0–0.3) were synthesized via the Pechini method, followed by calcination at 800 °C and characterization via a complex of physicochemical techniques. Regardless of the Fe content, solid solutions are single-phase complex oxides with a perovskite structure, as confirmed by X-ray diffraction. A decrease in the particle size from 75 to 29 nm and an increase in the specific surface area from 8.79 to 32.68 m2/g with increasing iron content were observed. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) revealed different chemical compositions between the surface and bulk layers of the solid solutions. Using these two methods, in conjunction with Mössbauer spectroscopy, it was shown that Fe2O3 oxide nanoparticles form on the surface of superstoichiometric perovskite-type oxides with x ≥ 0.2.
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