Influence of Rare‐Earth Pr ³⁺ Doped in Nickel Ferrite on Antibacterial Activity against Gram‐Positive and Gram‐Negative Bacteria

ABSTRACT Praseodymium (Pr 3+ )—doped nickel ferrite (NiFe 2‐x Pr x O 4 , x = 0.00, 0.025, 0.050, 0.075, 0.100, and 0.125) nanoparticles are successfully synthesized using the sol‐gel auto‐combustion method. X‐ray diffraction confirmed the formation of a single‐phase cubic spinel structure (Fd‐3m), with crystallite sizes ranging from 22–24 nm. The lattice parameter increased systematically with Pr 3 + incorporation, confirming ionic substitution at the Fe 3 + sites. FTIR spectra showed subtle shifts in absorption bands consistent with praseodymium doping. Raman spectroscopy indicated structural alterations due to Pr 3+ doping. Field emission scanning electron microscopy analysis revealed a compact microstructure composed of spherical particles, with sizes ranging from 32–37 nm. Energy dispersive X‐ray spectroscopy confirmed the stoichiometric composition of Ni, Fe, Pr, and O elements within the samples. BET analysis showed an increase in surface area from 7.25–8.10 m 2 g −1 upon Pr 3 + addition. The optical band gap, determined via Tauc's plot, increased slightly from 1.73–1.80 eV with rising Pr 3 + content. Magnetic measurements a decrease in saturation magnetization (44.92–34.38 emu g −1 ). The Pr 3 + ‐doped samples exhibited enhanced antibacterial activity against both Gram‐positive and Gram‐negative bacteria, attributed to reactive oxygen species generation and dopant‐induced surface interactions. These results highlight the tunable multifunctional behavior of Pr‐doped NiFe 2 O 4 nanoparticles, demonstrating their promise for biomedical and magnetic applications.