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Preparation and Properties of Fe3O4Nanoparticles and Its Composite Materials

Author: LinXiaoHui
Tutor: JiGuangBin
School: Nanjing University of Aeronautics and Astronautics
Course: Physical and chemical
Keywords: solvothermal ferrite electromagnetic wave absorbing composite material magneticparticle thermal reduction
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Type: Master's thesis
Year: 2013
Downloads: 14
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Abstract


In recent years, Fe3O4ferrite especially magnetic Fe3O4nanomaterials and its composites haveattracted more attentions and studies because of its potential applications in ferrofluid, magneticabsorbing material and biomedicine. Hollow structured magnetite spheres with various sizes werefabricated by a simple solvothermal process. The morphology and crystal structures of the productswere characterized by X-ray diffraction （XRD）, emission scanning electron microscope （SEM） andtransmission electron microscopy （TEM）, respectively, and the vibration sample magnetometer（VSM）,FT-IR and m ssbauer were used to study the magnetic properties. The electromagnetic（EM）absorbing performance wave also studied. The Fe3O4@SiO2nanoparticles with core-shell structurewere prepared with the improved st ber and improved the Fe3O4oxide stability, under a hightemperature with reducing gas, the composite materials can convert to Fe@SiO2and Fe/Fe3O4@SiO2materials; Fe3O4/GNS composite materials were aiso prepared with different synthetic methods. Themagnetic properties and EM absorbing performance were investigated by VSM and vector networkanalyzer.Hollow structured Fe3O4naonospheres were successfully synthesised by the solvothermal process,with the assistance of various ammonium salts. Fe3O4spheres were ferromagnetic with smallhysteresis loops and the values of saturation magnetization are82.989,78.049and87.417emu/g forS-a,S-b and S-c samples, which decreases with increasing particle size. The maximum reflection lossup to-40dB appeared in89GHZ for the hollow structure samples. Fe3O4@SiO2nanoparticles withcore-shell structures were fabricated through control of different experimental conditions. Fe@SiO2materials were obtained under hydrogen atmosphere, the reduced composite materials have greatreflection loss over a wide frequency range, and the stability of composite material were enhanced,but the thickness with best reflection loss is bigger. The Fe3O4/GNS composite materials wereobtained by solvent thermal method in situ with acetylacetone iron as iron source. In the Fe3O4/GNScomposite, the Fe3O4particles has good dispersion. The magnetization （M） of the Fe3O4/GNScomposite is low. Compared to the Fe3O4, the value of reflection loss is decrease but the absorptionband of the composite material increases.

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