Sol-Gel Synthesis and Characterization of Yttrium-Doped MgFe₂O₄ Spinel

In this study, an environmentally friendly sol-gel synthetic approach was used for the preparation of yttrium-doped MgFe₂O₄. Two series of compounds with different iron content were synthesized and A-site substitution effects were investigated. In the first series, the iron content was fixed and the charge balance was suggested to be compensated by a partial reduction of Fe³⁺ to Fe²⁺ or formation of interstitial O^2- ions. For the second series of samples, the iron content was reduced in accordance with the substitution level to compensate for the excess of positive charge, which accumulates due to replacing divalent Mg²⁺ with trivalent Y³⁺ ions. Structural, morphological and magnetic properties were inspected. It was observed that single-phase compounds can only form when the substitution level reaches 20 mol% of Y³⁺ ions and iron content is reduced. The coercivity as well as saturation magnetization decreased with the increase in yttrium content. Mössbauer spectroscopy was used to investigate the iron content in both tetrahedral and octahedral positions.