Authors: C.W. Lee, S.G. Kim, Jai Sung Lee
Abstract: The influence of reaction temperature on phase evolution of iron oxide hollow
nanoparticles during chemical vapor condensation (CVC) process using iron acetylacetonate was
investigated. X-ray diffraction (XRD) analyses revealed that three iron oxide phases (α-Fe2O3,
γ-Fe2O3, and Fe3O4) and a mixture of β-Fe2O3 and small amount of γ-Fe2O3 were synthesized at
700oC and 900oC, respectively. TEM observation disclosed that the iron oxide particles are almost
composed of hollow structured nanoparticles of 10~20 nm in size and 3~5 nm in shell thickness. This
result implies that reaction temperature determining various reaction parameters plays an important
role for the phase- and structural evolutions of iron oxide hollow nanoparticles. Especially, the
present investigation attempted to explain temperature dependence of the phase evolution of β-Fe2O3
hollow nanoparticles in association with the decomposition of iron acetylacetonate.
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Authors: Jong Keun Ha, Kwon Koo Cho, Ki Won Kim, Tae Hyun Nam, Hyo Jun Ahn, Gyu Bong Cho
Abstract: Various physical, chemical and mechanical methods, such as inert gas condensation,
chemical vapor condensation, sol-gel, pulsed wire evaporation, evaporation technique, and
mechanical alloying have been used to synthesize nanoparticles. Among them, chemical vapor
condensation(CVC) represents the benefit for its applicability to almost materials because a wide
range of precursors are available for large-scale production with a non-agglomerated state. In this
work, iron nanoparticles and nanowires have synthesized by chemical vapor condensation(CVC)
process, using iron pentacarbonyl(Fe(CO)5) as precursor. The effects of processing parameters on the
morphology, microstructure and size of iron nanoparticles and nanowires were studied. Iron
nanoparticles and nanowires having various diameters were obtained by controlling the inflow of
metallic organic precursor. Both nanoparticles and nanowires were crystallized. Characterization of
obtained nanoparticles and nanowires were investigated by using a field emission scanning electron
microscopy, transmission microscopy and X-ray diffraction.
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Authors: Pramusanto, Hadi Purwanto, Yuhelda Dahlan, Nuryadi Saleh
Abstract: Iron sand deposit in Indonesia generally consisted of titanomagnetite with ilmenite lamelaa occurred in magnetite particle structure, therefore direct physical separation through magnetic method at particle size of 400 mesh only capable increasing total iron content up to 60%. In order to increase the grade of iron, decreasing TiO2 content in iron sand was applied by chemical method of alkaline fusion followed by grinding to 100 mesh and magnetic separation. Pre-oxidation was conducted prior to reduction and alkaline flux was added to coal based reduction system of in a rotary kiln. The alkali addition into the reduction system resulted to the formation of metallic iron and non metallic phases, in which sodium titanate compounds as nonmagnetic product can be separated from calcine using separator magnetic. XRD analyses of the concentrate and tailing as magnetic separation products showed concentrate was dominated by metallic phase compared to oxide phase and it doesn’t consisted iron-titan oxide and iron oxide. On the other hand, tailing was consisted iron-titan oxide and iron oxide.
801
Authors: Cheng Bin Du, Guo Jun Yu, Zhi Wei Gong
Abstract: The influence of carbonyl iron particles sizes on the properties of magneto-rheological fluids (MRFs) were studied. Different-sized carbonyl iron magnetic particles were prepared by ball milling with different milling times. On this basis, different particle MRF were prepared The off-state viscosity and the shear stress of the above MRFs were characterised and studied by an advanced rotational rheometer system. The test results show that the off-state viscosity and the shear stress of single-particle MRFs were enhanced with increasing average carbonyl iron particle size at a constant magnetic field. The shear stresses of MRFs containing two or three different particle sizes were significantly improved compared with the MRFs containing only a single particle size. At a reasonable level of medium and small size carbonyl iron particle spread throughout the structure of the multiple-particle MRFs, the defects in the chain structure were remedied when a chain reaction occurred, and the mechanical properties of MRFs were enhanced. Meanwhile, increased mass fractions of the small size carbonyl iron particle resulted in a reduction in overall average particle size of MRFs, and the mechanical properties of MRFs were also reduced. The mechanical properties of multiple-particle MRFs were observed to be strongly dependent on the size and mass fraction of the medium and small carbonyl iron particles.
623
Authors: Wan Ju Zhang, Fang Wang
Abstract: Iron oxide (Fe3O4) nanoparticles as one of the most important nanomaterials are suitable for many applications. Monodisperse magnetic Fe3O4 nanoparticles were synthesized by the thermal decomposition of the iron oleate precursor in octadecene (ODE). The iron oleate complex was prepared by reaction between sodium oleic and FeCl3·6H2O at low temperature. The Fe3O4 nanoparticles were transferred from organic solvent into water by amphiphilic copolymer. The aqueous dispersion of Fe3O4 nanoparticles was stable in water and physiological buffers. This method with low cost can be used to prepare large scale of aqueous dispersion of Fe3O4 nanoparticles.
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