The present study is to synthesize iron oxide nanoparticles on different polysaccharide templates calcined at controlled temperature, characterizing them for spectroscopic and magnetic studies leading to evaluate their antibacterial property. The synthesized iron oxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy, high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer. The iron oxide nanoparticles were tested for antibacterial activity against grampositive and gram-negative bacterial species. The XRD confirms the crystalline nature of iron oxide nanoparticles with the mean crystallite size of 10 nm. The functional groups of the synthesized iron oxide nanoparticles were 547, 543 and 544 cm -1 characterizing the Fe-O and the broad bands at 3,398, 3,439 and 3,427 cm -1 were attributed to the stretching vibrations of hydroxyl group absorbed by iron oxide nanoparticles. HRTEM analyses revealed that the average particle size of the hematite nanoparticles are about 85, 92 and 77 nm for AF, DF and GF, respectively, which was a coincident with the results obtained from the HRSEM analysis. Magnetic measurement exhibited ferromagnetic behavior of the a-Fe 2 O 3 at the room temperature with higher coercivity of H C = 2,303, 2,333 and 1,019 Oe for AF, DF and GF, respectively. Antibacterial test showed the inhibition against Aeromonas hydrophila and Escherichia coli with significant antagonistic activity.

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Cerium (Ce)-doped Ni0.5Cd0.5CexFe2−xO4 (0.0 ≤ x ≤ 0.20) was synthesized using the sol–gel auto-combustion method. X-ray diffraction (XRD) analysis revealed that all the samples retained spinel cubic crystal structure with space group Fd3m at 800 °C. Crystal structure parameters, such as lattice constant, average crystallite size, and X-ray density were estimated from the major XRD (311) peak. Bulk density and porosity were also calculated. The average crystallite size was estimated to be in the range of 20–24 nm. SEM images displayed agglomerated particles with a porous morphology. The dielectric constant (ε′) increased and the dielectric loss tangent (tanδ) decreased with rising Ce concentration. The hysteresis loop (M–H loop) was measured at room temperature using a vibrating-sample magnetometer (VSM), which showed a nonlinear decrease in magnetization and coercivity with increasing Ce concentration.