Influence of the composition of the initial reagents on the structural and magnetic properties of Sr1.5La0.5FeMoO6-δ

This paper presents investigations of phase transformations during the crystallization of Sr_1.5La_0.5FeMoO_6-δ by the solid-phase method from a stoichiometric mixture of MoO₃, La₂O₃, Fe₂O₃ and SrCO₃ oxides, as well as precursors Sr_0.5La_0.5FeO₃ and SrMoO₄. Using the XRD and thermogravimetric analyses, influence of synthesis modes on the chemical processes during the formation of double perovskite was investigated. The synthesis of lanthanum-strontium ferromolybdate involves several series-parallel stages. Initially, the compound is enriched with iron, and its composition shifts towards higher molybdenum content. With increasing temperature, concentration of double perovskite increases while retaining the secondary phase, indicating the difficulty of solid-phase reactions. To reduce the influence of reaction intermediates, precursor materials are recommended. Optimized heating modes facilitated the production of single-phase Sr_1.5La_0.5FeMoO_6-δ powder, exhibiting 82% superstructural ordering. It has presented a Curie temperature of 450 K and a magnetization of 40.9 (A⋅m²)/kg at T = 77 K in B ≥ 0.86 T. 

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