Effect of synthesis method on the structure and magnetic behavior of LnFeO₃ (Ln = La, Nd, Sm, and Gd) nanoparticles

Abstract

Rare-earth orthoferrites (LnFeO₃) are magnetic oxides of significant interest due to their perovskite structure and weak ferromagnetic behavior at room temperature. In this work, a comparative study on the synthesis of LnFeO₃ (Ln = La, Nd, Sm, and Gd) nanoparticles was performed using thermal decomposition of cyanometal complexes Ln[Fe(CN)₆]•nH₂O and sol–gel methods, including citrate and Pechini routes. The effects of the synthesis method and thermal conditions on the structural, morphological, and magnetic properties of the resulting oxides were systematically evaluated. Single-phase orthorhombic perovskites were obtained by controlled thermal decomposition, highlighting the influence of lanthanide contraction on oxide formation temperature. Optimization of calcination time enabled a significant reduction in synthesis temperature, yielding nanoparticles with reduced size. In contrast, sol–gel methods produced smaller and more homogeneous particles, although variations in stoichiometry and oxygen content were detected, which were attributed to structural defects. Magnetic measurements revealed weak ferromagnetic behavior characteristic of orthoferrites, with magnetization values dependent on the lanthanide cation, particle size, and synthesis route. These results demonstrate that rational selection of the synthetic strategy enables effective tuning of LnFeO₃ nanoparticle properties, providing useful guidelines for their design in catalytic, sensing, and biomedical applications.