• Journal of Magnetics
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• 제16권2호
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• pp.164-168
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• 2011

Magnetic nanoparticles can potentially be used in drug delivery systems and for hyperthermia therapy. The applicability of $Fe_3O_4$, $CoFe_2O_4$, $MgFe_2O_4$, and $NiFe_2O_4$ nanoparticles for the same was studied by evaluating their magnetization, thermal efficiency, and biocompatibility. $Fe_3O_4$ and $CoFe_2O_4$ nanoparticles exhibited large magnetization. $Fe_3O_4$ and $NiFe_2O_4$ nanoparticles exhibited large induction heating. $MgFe_2O_4$ nanoparticles exhibited low magnetization compared to the other nanoparticles. $NiFe_2O_4$ nanoparticles were found to be cytotoxic, whereas the other nanoparticles were not cytotoxic. This study indicates that $Fe_3O_4$ nanoparticles could be the most suitable ones for hyperthermia therapy.

• 한국분말재료학회지
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• 제24권3호
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• pp.229-234
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• 2017

We report on a simple and robust route to the spontaneous assembly of well-ordered magnetic nanoparticle superstructures by irreversible evaporation of a sessile single droplet of a mixture of a ferrofluid (FF) and a nonmagnetic fluid (NF). The resulting assembled superstructures are seen to form well-packed, vertically arranged columns with diameters of $5{\sim}0.7{\mu}m$, interparticle spacings of $9{\sim}2{\mu}m$, and heights of $1.3{\sim}3{\mu}m$ The assembled superstructures are strongly dependent on both the magnitude of magnetic field and the mixing ratio of the mixture. As the magnitude of the externally applied magnetic field and the mixing ratio of the mixture increase gradually, the size and interspacing of the magnetic nanoparticle aggregations decrease. Without an externally applied magnetic field, featureless patterns are observed for the ${\gamma}-Fe_3O_4$ nanoparticle aggregations. The proposed approach may lead to a versatile, cost-effective, fast, and scalable fabrication process based on the field-induced self-assembly of magnetic nanoparticles.

• Journal of Ceramic Processing Research
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• 제21권2호
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• pp.278-283
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• 2020

We report the synthesis of citrate stabilized iron oxide (C-Fe3O4) spherical nanoparticles for supercapacitor electrodes. The citrate functional group present in the surface of the Fe3O4 nanoparticles effectively controls the morphology and the surface area of the nanostructures. The C-Fe3O4 electrodes exhibited a battery-like energy storage properties with a maximum specific capacity of 146 Cg-1 (242 Fg-1) which is much higher than the specific capacity of citrate free Fe3O4 electrode (62 Cg-1; 112 Fg-1). Moreover, the C-Fe3O4 electrode showed better cyclic stability (75%) than the citrate free Fe3O4 electrode (~35%) after 1000 charge/discharge cycles.

• 한국자기학회지
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• 제16권1호
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• pp.40-44
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• 2006

졸-겔법을 이용하여 나노 입자 $Zn_{0.5}Ni_{0.5}Fe_2O_4$를 제조하여 x선 회절법(XRD) 및 주사전자현미경(SEM) 측정을 통하여 결정학적 특성 및 입자의 크기를 연구하였으며, 제조된 나노 입자의 초상자성 성질을 Mossbauer분광법, 진동시료 자화율 측정기(VSM)를 이용하여 연구하였다 XRD및 SEM의 측정으로부터 열처리 온도가 $300^{\circ}C$에서 순수한 cubic spinel구조를 가지며, 이 때 열 처리한 시료의 평균입자 크기는 7nm인 균일한 구형상 임을 알 수 있었다 Mossbauer분광실험으로 $300^{\circ}C$에서 열처리한 입자가 상온에서 초상자성의 특성을 가지고 있음을 알 수 있었으며, 4.2K에서의 초미세자기장은 $H_{hf}$ (B-자리)=510, $H_{hf}$(A-자리)=475 kOe, 이성질체 이동 값은 0.37(B-자리), 0.33mm/s(A-자리)로 분석되었다. VSM측정 결과로부터 상온에서 초상자성 특성을 갖는 7nm $Zn_{0.5}Ni_{0.5}Fe_2O_4$의 차단온도 $T_B$는 90 K로 결정하였으며, 자기이방성상수 $K=1.6\times10^6\;erg/cm^3$ 값을 얻었다.

• 한국세라믹학회지
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• 제47권4호
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• pp.338-342
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• 2010

Co, $Fe_3O_4$ and Co/$Fe_3O_4$ nanoparticles were synthesized by a polyol process in order to develop their new applications and improve chemical, magnetic properties. The synthesis involved a polyol process using Fe, Co acetylacetonate as precursors and 1-2 hexadecanediol as the polyol. The synthesized $Fe_3O_4$ and Co/$Fe_3O_4$ nanocomposite particles were monodispersed and self arrayed ranging in size of 8~10 and 10~25 nm, respectively. The Co nanoparticle has a crystallite size of 10~40 nm. The synthesized nanoparticles were characterized by their structural, morphological, compositional and magnetic properties using TEM-EDS, XRD, and PPMS techniques.

• Bulletin of the Korean Chemical Society
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• 제30권6호
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• pp.1305-1308
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• 2009

The experimental particle samples included ($Mn_{0.1}Fe_{0.9}$)O-$Fe_2O_3$ and FeO-($Gd_{0.1}Fe_{0.9}$)$_2O_3$ with $Mn^{2+}\;and\;Gd^{3+}$ substitutions in inverse spinel $Fe_3O_4$. A lecithin surfactant was adsorbed onto the magnetic particles by ultrasonication. The samples prepared showed excellent dispersibility at the mean size of 13 nm; their saturation magnetization values were 63 emu/g for the bare and Mn-substituted magnetites, and 56 emu/g for the Gd-substituted magnetite. The crystal structure of the substituted magnetites was very similar to that of the bare magnetite, due to a small amount of 0.1 mole fraction substituted in synthesizing the magnetite. The magnetite fluids, according to T2-weighted MR images, effectively diminished the signal intensity in the liver and spleen of Sprague-Dawley rats.

• Bulletin of the Korean Chemical Society
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• 제21권12호
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• pp.1193-1198
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• 2000

The preparation of nanocrystalline hematite, ${\alpha}-Fe_2O_3$, paricles and their surface coating with silica layers are described. The hematite particles with the size of 30~60 nm are firstly prepared by thermal decomposition of trinuclear acetate-hydroxo iron (III) nitrate complex, $[Fe_3$(OCOCH_3)_7$OH${\cdot}$2H_2O]NO_3$, at $400^{\circ}C$. Subsequently the hematite surfaces are coated with siliva layers by a controlled hydrolysis and condensation reaction of TEOS with varying the TEOS concentration and pH. Monodispersed and spherical $SiO_2-coatedFe_2O_3$ particles with the average particle diameter of ~90 nm and extremely narrow size distribution can be obtained at the pH of 11 and the TEOS concentration of 0.68M, which are found to be the optimum conditions in the present study in achieving the homogeneous deposition of silica layers on hematite surfaces. Diffuse reflectance UV-Vis spectra reveal that the characteristic optical reflectance of ${\alpha}-Fe_2O_3$ particles is preserved almost constant even after coating the surfaces, suggesting that the $SiO_2$ layers can be regarded as protecting layers without degrading the optical properties of hematite particles.

• Archives of Metallurgy and Materials
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• 제66권3호
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• pp.771-776
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• 2021

Iron oxide nanoparticles were incorporated to form composite microspheres of SiO₂ and Fe₂O₃ for magnetic separation of the particles after adsorption or photochemical decomposition. Economic material, sodium silicate, was purified by ion exchange to prepare aqueous silicic acid solution, followed by mixing with iron oxide nanoparticles. Resulting aqueous dispersion was emulsified, and composite microspheres of SiO₂ and Fe₂O₃ was formed from the emulsion droplets as micro-reactors during heating. Removal of methylene blue using the composite microspheres was performed by batch adsorption process. Synthesis of composite microspheres of silica containing Fe₂O₃ and TiO₂ nanoparticles was also possible, the particles could be separated using magnets efficiently after removal of organic dye.

• 대한환경공학회지
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• 제36권6호
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• pp.396-401
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• 2014

나노물질은 다양한 분야에 널리 사용되고 있다. 본 연구에서는 Lactuca(상추)와 Raphanus(알타리무) 씨앗의 발아와 발아지수에 금속산화물 나노입자(CuO, NiO, $Fe_2O_3$, $Co_3O_4$, $TiO_2$, ZnO)가 미치는 영향을 조사하였다. 용액상 노출에서 CuO가 가장 큰 영향을 나타내었으며, 발아와 발아지수의 $EC_{50}$는 각 0.46 mg/L와 0.37%로 조사되었다. 씨앗 이용 식물독성 측정에서 상추가 알타리무보다 나노입자 노출에 대해 더욱 민감한 반응을 나타내었다. 일반적으로 나노입자의 씨앗발아와 발아지수에 근거한 영향은 다음의 순서로 조사되었다: CuO > ZnO >NiO > $TiO_2$, $Fe_2O_3$, $Co_3O_4$. 특히 $TiO_2$, $Fe_2O_3$와 $Co_3O_4$는 최대 노출 농도 1,000 mg/L 농도에서도 뚜렷한 영향을 나타내지 않았다.

• Journal of Yeungnam Medical Science
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• 제28권2호
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• pp.145-152
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• 2011

Background: To evaluate the changes in the radiation dose and temperature distribution on irradiated egg albumin and nanoparticle ($Fe_3O_4$) powder mixed egg albumin. Methods: A new type of phantom was designed by fabricating a $30{\times}30{\times}30cm$ acryl square inside a $3{\times}3{\times}3cm$ small square and dividing it into two parts. In the control group, only egg albumin was irradiated, and in the test group, 25 nm 20 mg/cc, 25 nm 40 mg/cc, and 1 um 40mg/cc nanoparticles with egg albumin were irradiated. The radiation isodose distributions and temperature changes were then observed. Results: No significant changes were observed in the radiation dose and temperature distribution. Conclusion: The nanoparticles were considered not to have had any effect on the radiation dose and temperature distribution under the experimental conditions. Further studies can be conducted based on the changes in the mixture material.