Impact of Mn²⁺ substitution on physical and antibacterial properties of ZnFe₂O₄ nanoparticles

The sol-gel method is employed for the preparation of zinc ferrite nanoparticles. The effect of Mn²⁺ substitution on the morphological, structural, optical and magnetic properties of zinc ferrite nanoparticles was studied. X-ray diffraction and Fourier transform infrared spectroscopic analyses evidence the presence of cubic spinel structure with Fd3-barm space group. The average size of crystallites determined using the Scherrer formula for manganese-doped and pure zinc ferrite nanoparticles ranged from 7 to 20 nm. Purity and elemental composition were evidenced by energy dispersive X-ray analysis. The bandgap estimated from UV-visible spectra was 1.89-2.21 eV. The saturation magnetization (M_s), retentivity (M_r) and coercivity (H_c) were estimated from hysteresis curves of all samples that depicted ferromagnetic characteristics. The synthesized nanoparticles exhibited good antibacterial activity against both gram-positive (Lactobacillus and Staphylococcus aureus) and gram-negative (Vibrio cholerae and Pseudomonas aeruginosa) strains. (author)