Abstract

LOPEZ, Javier A et al. Synthesis and characterization of Fe₃O₄ magnetic nanofluid. Rev. LatinAm. Metal. Mater. [online]. 2010, vol.30, n.1, pp.60-66. ISSN 0255-6952.

Ferrofluids are colloidal systems composed of single domain of magnetic nanoparticles dispersed in a liquid carrier. In the present work, Fe₃O₄ magnetic ferrite nanoparticles were synthesized by chemical coprecipitation method, and were coated with oleic acid as surfactant agent. Magnetic properties of nanoparticles in ferrofluids were investigated with the aid of a vibrating sample magnetometer (VSM) at room temperature. Superparamagnetic behavior, characteristic of magnetic nanoparticles, was determined from the hysteresis loop of M vs. H measurements. The sample as powder was characterized by means of X-ray diffraction. XRD pattern result shows the presence of the most intense peak corresponds to the (311) crystallographic orientation of the spinel phase of Fe₃O₄ magnetic nanoparticles. The mean size of the nanoparticles was determined from the X-ray diffraction pattern by using the Scherrer approximation. The particle size was calculated to be 9.64 nm. Atomic Force Microscopy was used to visualize the morphology of nanoparticles and to measure their diameter. The AFM method showed an average nanoparticles diameter of D_N = 15.3 nm. FTIR absorption spectroscopy was used to confirm the formation of Fe-O bonds, allowing to identify the inverse ferrites spinel structure, as well as, the presence of other chemical substances adsorbed on the surface of particles.

Keywords : Ferrofluids; nanoparticles; coprecipitation chemical synthesis; spinel structure.