Synthesis And Characterization Of Magnetic Nanoparticles

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Synthesis And Characterization Of Magnetic Nanoparticles

Show simple item record Poudyal, Narayan en_US 2007-08-23T01:56:32Z 2007-08-23T01:56:32Z 2007-08-23T01:56:32Z August 2005 en_US
dc.identifier.other DISS-1091 en_US
dc.description.abstract Synthesis of uniform nanoparticles (<100 nm) of hard and soft magnetic materials have attracted much attention in the last two decades because of their unique magnetic properties and potential for many applications such as high density recording media, biotechnology, ferrofluids, and fabrication of exchange-coupled nanocomposite permanent magnets. In this thesis, synthesis and characterization of hard (FePt) and soft (Fe3O4 and CoFe2O4) magnetic nanoparticles with different sizes are reported. Monodisperse FePt, Fe3O4 and CoFe2O4 nanoparticles were synthesized by chemical solution methods. Particle diameter was tuned from 3 to 20 nm by varying reaction conditions or by seed-mediated growth method. Monodisperse face-centered tetragonal (fct) FePt nanoparticles were prepared by annealing at 700oC the disodered face-centered cubic (fcc) FePt nanopaticles in NaCl matrix to convert the fcc particles into ordered fct structure. Morphological, structural, and compositional characterizations of the nanoparticles were performed by Transmission Electron Microscopy (TEM), High resolution TEM (HRTEM), Laser Particle-Size Analyzer, X-ray Diffractometer (XRD), Energy Dispersive X-ray (EDX), and Inductively Coupled Plasma (ICP). Magnetic properties of nanoparticles of different sizes at different temperatures were studied by Anternating Gradiant Magnetometer (AGM), and Superconducting Quantum Interference Device (SQUID) magnetometer. It has been found that all the as-synthesized Fe3O4 nanoparticles up to 20 nm are superparamagnetic at room temperatue while CoFe2O4 nanoparticles larger than 12 nm are ferromagnetic. An exchange bias field up to 3 kOe was observed for 3 nm CoFe2O4 nanoparticles in field cooling measurements. Very high coercivity of the isolated fct FePt nanoparticles up to 30 kOe at room temperature has been obtained. Interesting experimental results on the size dependent magnetic properties for both the hard and soft magnetic nanoparticles at different temperatures have been found. en_US
dc.description.sponsorship Liu, J. Ping en_US
dc.language.iso EN en_US
dc.publisher Physics en_US
dc.title Synthesis And Characterization Of Magnetic Nanoparticles en_US
dc.type M.S. en_US
dc.contributor.committeeChair Liu, J. Ping en_US Physics en_US Physics en_US University of Texas at Arlington en_US masters en_US M.S. en_US
dc.identifier.externalLinkDescription Link to Research Profiles

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