A facile route to synthesis NixFe1−xFe2O4 ferrofluids with optimal rheological and magneto‐optical properties

Abstract This study presents an easy method for synthesizing ultrafine Ni x Fe 1– x Fe 2 O 4 nanoparticles with adjustable composition ( x = 0–.8), followed by their stabilization into ferrofluids. Structural identification of the crystalline structure, lattice points, and grain boundaries from the broadened diffraction peaks reveal an average crystalline size of the nanoparticles as 10–16.5 nm. Transmission electron microscopy images reveal spherical magnetite nanoparticles with a particle size ranging from 6 to 13 nm, consistent with diffraction studies. In ferrofluids, the Ni x Fe 1– x Fe 2 O 4 nanoparticles are stabilized in kerosene with oleic acid, a surfactant. Absorbance data of the ferrofluids is seen in the 200–400 nm wavelength region of UV–vis spectra. The magnetic properties of the samples are probed using a Superconducting Quantum Interference Device. The synthesized samples exhibit superparamagnetic behavior at room temperature (300 K). The saturation magnetization of the samples decreases with an increase in Ni composition ( x = 0–.8), ranging from 54 to 28 emu/g. This study explores the magnetic and magneto‐optical properties of Ni x Fe 1– x Fe 2 O 4 ferrofluids. Magneto‐viscosity of ferrofluids is also studied, and the final application of such ferrofluids in data storage, catalysis, and biomedical applications is discussed.