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SYNTHESIS AND CHARACTERIZATION OF Fe 3 O 4 MAGNETIC NANOFLUID

2010; Linguagem: Espanhol

2244-7113

J. López, Ferney González, F.A. Bonilla, G. Zambrano, M. E. Gómez,

Characterization and Applications of Magnetic Nanoparticles

Ferrofluids are colloidal systems composed of single domain of magnetic nanoparticles dispersed in a liquid carrier. In the present work, Fe 3 O 4 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 Fe 3 O 4 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. Los ferrofluidos son sistemas coloidales compuestos de nanoparticulas magneticas con mono-dominios magneticos, dispersas en un liquido portador. En el presente trabajo, nanoparticulas magneticas de ferrita (Fe 3 O 4 ) se sintetizaron por el metodo de co-precipitacion quimica, y se recubrieron con acido oleico como agente surfactante. Las propiedades magneticas de las nanoparticulas en el ferrofluido fueron investigadas por medio de un magnetometro de muestra vibrante (VSM) a temperatura ambiente, mostrando un comportamiento superparamagnetico, caracteristico de estas nanoparticulas magneticas. Esto se determino a partir de la curva de histeresis de M vs H. La muestra en polvo se caracterizo por medio de Difraccion de Rayos X. El patron DRX resultante muestra la presencia del pico mas intenso correspondiente a la orientacion cristalografica (311) de la fase espinel para las nanoparticulas magneticas de Fe 3 O 4 . El tamano medio de las nanoparticulas se determino a partir del patron de difraccion de rayos X utilizando la aproximacion de Scherrer, siendo este tamano medio de 9,64 nm. La microscopia de fuerza atomica, se utilizo para visualizar la morfologia de las nanoparticulas y para determinar su diametro. Las medidas de AFM muestran un diametro promedio para las nanoparticulas de DN = 15,3 nm La espectroscopia de absorcion FTIR se utilizo para confirmar la formacion de los enlaces Fe-O, permitiendo identificar la estructura tipo espinela de la ferrita, asi como la presencia de otras sustancias quimicas adsorbidas en la superficie de las particulas.