This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite （Fe3O4） nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction....This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite （Fe3O4） nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction. The XRD results show that a weakly magnetic induction below 220 Gs could accelerate the phase transformation from goethite （α-FeOOH） to magnetite （Fe3O4）, and affect the crystal structure, the particle size/morphology and magnetic response of the magnetite nano-particles synthesized. In addition, a higher concentration of the FeCl2 solution in the synthesis reaction led to finer particles, both with and without magnetic induction.展开更多
Uniform rhombohedral α-Fe2O3 nanoparticles, -60nm in size, were synthesized via a triphenyl- phosphine-assisted hydrothermal method. Scanning electron micrograph （SEM） and transmission electron micrograph （TEM） a...Uniform rhombohedral α-Fe2O3 nanoparticles, -60nm in size, were synthesized via a triphenyl- phosphine-assisted hydrothermal method. Scanning electron micrograph （SEM） and transmission electron micrograph （TEM） analyses showed that the as-synthesized rhombohedral nanoparticles were enclosed by six （1 04） planes. The concentration of triphenylphosphine played an important role in morphological evolution of the α-Fe2O3 nanoparticles. The as-prepared rhombohedral nanoparticles possessed remanent magnetization Mr of 2.6 × 10^-3 emu/g and coercivity Hc of 2.05 Oe, both lower than those of other α-Fe2O3 particles with similar size, indicating their potential applications as superparamagnetic precursor materials. Furthermore, these rbombohedral α-Fe2O3 nanoparticles exhibited good sensor capability toward H2O2 with a linear response in the concentration range of 2-20 mM.展开更多
Main attention of this paper was devoted to studying the effect of solidification texture on microstructure（phase constituents,grain morphology,and magnetic domain structure） of polycrystalline Fe_（82）Ga_（18） sa...Main attention of this paper was devoted to studying the effect of solidification texture on microstructure（phase constituents,grain morphology,and magnetic domain structure） of polycrystalline Fe_（82）Ga_（18） sample.The alloy was melted using button arc melting and solidified in water-cooled copper mold.Optical microscope（OM） results confirm the development of large columnar grains in the solidification microstructure.Phase constitution and magnetic domain structures of the sample were studied by X-ray diffraction（XRD） and magnetic force microscopy（MFM）.Results show a single-phase solid solution with an A2 structure for the sample which consists of regularly aligned magnetic domains.Although some maze-like subdomains are found in few regions,well-aligned stripe-like domains are predominant patterns in the sample.It demonstrates the high dependence of grain morphology and magnetic domain structure upon a preferred crystallographic direction during solidification.展开更多
文摘This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite （Fe3O4） nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction. The XRD results show that a weakly magnetic induction below 220 Gs could accelerate the phase transformation from goethite （α-FeOOH） to magnetite （Fe3O4）, and affect the crystal structure, the particle size/morphology and magnetic response of the magnetite nano-particles synthesized. In addition, a higher concentration of the FeCl2 solution in the synthesis reaction led to finer particles, both with and without magnetic induction.
基金supported by the National Natural Science Foundation of China(No.21003147)Natural Science Foundation of Shanxi(2011011007-3)the State Key Laboratory of Coal Conversion(SKLCC) in-house project(No.2011BWZ005)
文摘Uniform rhombohedral α-Fe2O3 nanoparticles, -60nm in size, were synthesized via a triphenyl- phosphine-assisted hydrothermal method. Scanning electron micrograph （SEM） and transmission electron micrograph （TEM） analyses showed that the as-synthesized rhombohedral nanoparticles were enclosed by six （1 04） planes. The concentration of triphenylphosphine played an important role in morphological evolution of the α-Fe2O3 nanoparticles. The as-prepared rhombohedral nanoparticles possessed remanent magnetization Mr of 2.6 × 10^-3 emu/g and coercivity Hc of 2.05 Oe, both lower than those of other α-Fe2O3 particles with similar size, indicating their potential applications as superparamagnetic precursor materials. Furthermore, these rbombohedral α-Fe2O3 nanoparticles exhibited good sensor capability toward H2O2 with a linear response in the concentration range of 2-20 mM.
基金support of Center of Excellence for High Performance Materials (CEPMAT) at University of Tehran, Sahand University of Technology
文摘Main attention of this paper was devoted to studying the effect of solidification texture on microstructure（phase constituents,grain morphology,and magnetic domain structure） of polycrystalline Fe_（82）Ga_（18） sample.The alloy was melted using button arc melting and solidified in water-cooled copper mold.Optical microscope（OM） results confirm the development of large columnar grains in the solidification microstructure.Phase constitution and magnetic domain structures of the sample were studied by X-ray diffraction（XRD） and magnetic force microscopy（MFM）.Results show a single-phase solid solution with an A2 structure for the sample which consists of regularly aligned magnetic domains.Although some maze-like subdomains are found in few regions,well-aligned stripe-like domains are predominant patterns in the sample.It demonstrates the high dependence of grain morphology and magnetic domain structure upon a preferred crystallographic direction during solidification.
