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Preparation and Characterization of FePt Nanostructures and FePt-Inorganic Matrix Composite Systems

Author: ZhangJunLong
Tutor: LiAiDong
School: Nanjing University
Course: Materials Physics and Chemistry
Keywords: FePt nanostructures Superparamagnetic effect Ultra - high density magnetic storage The FePt- inorganic dielectric composite system
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 44
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Abstract


Along with the rapid development of information technology, information storage is crucial. Magnetic recording technology as one of the mainstream memory devices, has been innovation. Traditional industrial magnetic material such as CoPtCr, due to the limitations of the superparamagnetic effect has not meet the requirements of the increasing development of ultra-high density magnetic storage. FePt / CoPt L10 phase material, with its high magneto-crystalline anisotropy energy and good chemical stability, oxidation resistance, people pay attention. In this paper, the iron pentacarbonyl and acetylacetone platinum as a raw material, and synthesized FePt nano-particles with a solution method, the FePt nanowires or the like structure. Meanwhile, in order to solve the reunion in the high-temperature annealing of FePt nanoparticles prepared several FePt-inorganic medium (FePt-MgO, FePt-TiO2 and the FePt-SiO2) composite system, by means of XRD, TEM, VSM analysis characterization able to conduct a more in-depth characterization of the structure, morphology and magnetic. The progress of this thesis is as follows: 1. FePt nano-particles synthesized by a solution method, by changing the reaction conditions (the reaction temperature and the reaction was the initial molar ratio), can determine the optimal synthetic conditions. At the reaction temperature 220 ° C, Fe-Pt initial molar ratio of 2:1, the fcc phase synthesized FePt nano-particles, the stoichiometric ratio close to 1:1, the particle diameter of around 4nm, has good monodispersion . After annealing at high temperature, the degree of ordering of 0,96 showed good magnetic the coercivity above 70000e, but agglomeration serious. 2 to control the reaction conditions, the solvent was replaced oleylamine and hexadecane at 180 ℃ successfully synthesized length in of 40 ~~ 100 nm, width of about 2nm FePt nano line. The length of the nanowire can be changed by changing the proportion of the solvent oleylamine and hexadecane, but the width remains unchanged. Analyzed lattice and elemental composition of the nanowire, Fe-Pt atomic ratio of 0.54:0.46. Due to incomplete annealing L10 phase change, resulting in a large amount of the soft magnetic phase exists, and thus the FePt nano line measured after annealing the coercive force is small. 3 hydrophilic FePt nanoparticles, the sol-gel method successfully prepared FePt-MgO. FePt-TiO2 and FePt-SiO2 composite system. Found after high temperature annealing, the matrix of the inorganic dielectric, to effectively prevent agglomeration of the particles of the FePt, maintaining a good dispersion, and the composite film of FePt particles equally effective L10 phase transition, but compared with the pure FePt particles chemical order parameter S fell roughly in the range of 0.6 to 0.8. The system FePt concentration and oxide sol of pH on the structure and magnetic properties of the media FePt-inorganic composite system. FePt concentration and pH value of the precursor of the magnetic properties of the composite system can have a significant impact on FePt-MgO system, measured when FePt: MgO = 1:2 pH value of 7 is better rectangular hysteresis return line, rectangle degree of 64.4%, has the highest coercive force of 46640e, and the FePt particles in the composite film exhibited good dispersibility. FePt-TiO2 composite system, under acidic conditions (pH value of 5.5) of FePt: TiO2 = 1:2, obtained with the FePt-MgO system similar dispersibility and magnetic characteristics, the coercive force of 44360e. FePt-SiO2 composite system, pH = 9, the coercive force of about 33000e, process and performance needs further optimization.

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