Magnetic, Optical, and Antibacterial Properties of Ag+ and Ti4+ Doped Cobalt Ferrite Nanocrystals

In this paper, we explore the magnetic, optical, and antibacterial properties of $${\text{CoF}}{{{\text{e}}}_{2}}{{{\text{O}}}_{4}}$$ (CFO), $${\text{C}}{{{\text{o}}}_{{0.98}}}{\text{A}}{{{\text{g}}}_{{0.02}}}{\text{F}}{{{\text{e}}}_{2}}{{{\text{O}}}_{4}}$$ (CAFO), and $${\text{C}}{{{\text{o}}}_{{0.98}}}{\text{T}}{{{\text{i}}}_{{0.02}}}{\text{F}}{{{\text{e}}}_{2}}{{{\text{O}}}_{4}}$$ (CTFO) and spinel ferrite nanocrystals. The XRD analysis of these crystals reveals a single-phase cubic structure of $$Fd\bar {3}m$$ space group with a crystallite size of 45, 46, and 41 nm, respectively. The room temperature magnetic measurement shows that CTFO has the highest saturation and remanent magnetization, whereas CFO has the highest coercivity and magnetic squareness ratio. Optical properties of these samples have been taken in the range of 300–900 nm. The band gap is calculated using Tauc’s plot, and it decreases with the doping of $${\text{A}}{{{\text{g}}}^{ + }}$$ and $${\text{T}}{{{\text{i}}}^{{4 + }}}$$ ions. Antibacterial studies of these samples have been done by disc diffusion method for Gram-positive and Gram-negative bacteria, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), respectively. The compositions have shown better antibacterial response for S. aureus over E. coli. The 200 mg/mL CTFO sample has shown the most effective result against S. aureus bacteria, with 18 mm diameter value of zone of inhibition.