Gd-doped Zn _0.5 Mg _0.5 Fe ₂ O ₄ nanoparticles: structural, magnetic, and antimicrobial investigations

Abstract Gadolinium (Gd)-doped Zn 0.5 Mg 0.5 Fe 2 O 4 nanoparticles were fabricated using the hydrothermal method to evaluate their structural, magnetic, and antimicrobial properties. X-ray diffraction (XRD) and Raman spectroscopic data confirmed the cubic spinel structure of all samples, with the structural analysis showing a continuous expansion in the lattice parameter, while the crystallite size of the particles decreased as the concentration of Gd increased. Field emission scanning electron microscopy (FESEM) showed spherical particles with a high degree of agglomeration with diameters of 36–48 nm, which supported the XRD data. Magnetic studies demonstrated an increase in saturation magnetization (Ms) and a decrease in coercivity (Hc) which indicated superparamagnetic behavior at the higher Gd concentrations. Antimicrobial activity measured against Staphylococcus , E. coli , and Candida , showed that the higher Gd-doped samples had significant inhibition zones, whereas lower Gd content samples were unable to show any activity. Zeta potential analysis also illustrated the necessity of surface charge as a significant variable in the antimicrobial activity. The study shows that Gd-doped Zn 0.5 Mg 0.5 Fe 2 O 4 samples are multi-functional, and they have potential as new multifunctional materials for magnetic devices or antimicrobial applications.