• 자원리싸이클링
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• 제11권5호
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• pp.7-10
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• 2002

Iron nitride magnetic fluid was oxidized by exposing it to the air under normal atmospheric conditions. After exposure of 3.2 hours, the relative saturation magnetization of the iron nitride magnetic fluid is less than 0.4 compared to the value of the unexposed sample, and it is nearly zero after exposure for 1008 hours. The structure of the oxidized iron nitride is considered to be a non-magnetic hematites. The thickness of the oxidation layers of the iron-nitride particles are nearly the same, about 3 nm, regardless of the different particle sizes.

• 한국전기전자재료학회논문지
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• 제30권12호
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• pp.782-787
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• 2017

There is growing interest in power inductors in which metal soft magnetic powder and epoxy resin are combined. In this field, the process technology for increasing the packing density of magnetic particles in an injection molding process is very important. However, little research has been reported in this regard. In order to improve the packing density, we investigated and compared the sedimentation heights of pastes for three types of soft magnetic alloy powders as a function of the mixing ratios and the type of resin used. Experimental results showed that the packing density was the highest (71.74%) when the mixing ratio was 80 : 16 : 4 (Sendust : Fe-S : CIP) according to the particle size using an SE-4125 resin. In addition, the packing density was found to be inversely related to the layer separation distance. As a result, it was confirmed that the dispersion of solid particles in the paste was important for curing; however, the duration of the curing process can greatly affect the packing density of the final composite.

• Korean Chemical Engineering Research
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• 제55권3호
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• pp.287-295
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• 2017

Using nanotechnology, magnetic nanoparticles of iron oxide were produced via co-precipitation method and followed modification with organic compounds. In the next step, functionalized monomer was provided via coupling ${\beta}$-cyclodextrine and allylamine onto modified magnetic nanoparticles. These nanoparticles were used to establish the adsorption rate of celecoxib. Magnetic nanoparticles are modified by (3-mercaptopropyl)trimethoxysilane. Nano-adsorbent was characterized by analytical and spectroscopic methods, such as Fourier transform infrared spectroscopy, elemental analysis, thermo-gravimetric analysis, and transmission electron microscopy (TEM). Laboratory parameters, such as the kinetics of adsorption isotherms, pH, reaction temperature and capacity were optimized. Finally, by using this nano-adsorbent in the optimized condition, extraction of celecoxib from biological samples as urine, drug matrix and blood plasma was carried out by high performance liquid chromatography with sensitivity and high accuracy.

• 한국자기학회지
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• 제26권4호
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• pp.129-132
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• 2016

열분해법으로 합성한 FePt 나노입자를 $NH_3+H_2$ 혼합가스 질화법으로 상변태와 동시에 질화시킨 FePtN 나노입자의 특성을 분석하였다. 초기 합성된 FePt 나노입자는 fcc 구조를 가졌으며, 보자력과 포화자화는 각각 247.34 Oe와 27.308 emu/g를 나타내었다. 혼합가스 질화법으로 열처리한 입자는 XRD 분석 결과 fcc 구조에서 fct 구조로 상변태가 진행되었으며, 열처리 온도의 증가에 따라 (111) 피크의 $2{\theta}$가 shift되는 특성을 나타내었다. fct 구조의 FePtN의 보자력과 포화자화는 각각 1058.2 Oe and 32.718 emu/g를 나타내었으며, 합성된 FePtN 나노자성입자는 고밀도 자기기록매체와 생체의료 분야에서의 응용이 기대 된다.

• 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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.13-16
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• 2005

Nanoscale materials are of great interest due to their unique optical, electrical and magnetic properties. Due to the recent amazing achievements in nano technology, new materials were developed. But these nano technology is not apply to the construction part in spite of exellent properties of nano size material. The purpose of this study is to apply to nano technology into building materials. To develop the high performance concrete, nano cement particles is prepared by mechanical method. In the results of this study, the nano silica powder increase effect according to increase of the mixing amount, appeared that compressive strength increased but is limit in increment. For the production of high-strength concrete, nano silica powder was suitable the binder ratio from 20$\%$. And, the compressive strength of concrete are especially dependent on the curing temperature.

• Journal of Magnetics
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• 제19권1호
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• pp.59-63
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• 2014

Nano-sized nickel substituted cobalt ferrite powders, $Ni_xCo_{1-x}Fe_2O_4$ ($0.0{\leq}x{\leq}1.0$), were fabricated by the sol-gel method, and their crystallographic and magnetic properties were studied. All the ferrite powders showed a single spinel structure, and behaved ferrimagnetically. When the nickel substitution was increased, the lattice constants and the sizes of particles of the ferrite powders decreased. The M$\ddot{o}$ssbauer absorption spectra of $Ni_xCo_{1-x}Fe_2O_4$ ferrite powders could be fitted with two six-line subspectra, which were assigned to a tetrahedral A-site and octahedral B-sites of a typical spinel crystal structure. The increase in values of the magnetic hyperfine fields indicated that the superexchange interaction was stronger, with the increased nickel concentration in $Ni_xCo_{1-x}Fe_2O_4$. This could be explained using the cation distribution, which can be written as, $(Co_{0.28-0.28x}Fe_{0.72+0.28x})[Ni_xCo_{0.72-0.72x}Fe_{1.28-0.28x}]O_4$. The two values of the saturation magnetization and the coercivity decreased, as the rate of nickel substitution was increased. These decreases could be explained using the cation distribution, the magnetic moment, and the magneto crystalline anisotropy constant of the substituted ions.

• 한국재료학회지
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• 제21권6호
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• pp.327-333
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• 2011

Nanostructured cobalt materials have recently attracted considerable attention due to their potential applications in high-density data storage, magnetic separation and heterogeneous catalysts. The size as well as the morphology at the nano scale strongly influences the physical and chemical properties of cobalt nano materials. In this study, cobalt nano particles synthesized by a a polyol process, which is a liquid-phase reduction method, were investigated. Cobalt hydroxide ($Co(OH)_2$), as an intermediate reaction product, was synthesized by the reaction between cobalt sulphate heptahydrate ($CoSO_4{\cdot}7H_2O$) used as a precursor and sodium hydroxide (NaOH) dissolved in DI water. As-synthesized $Co(OH)_2$ was washed and filtered several times with DI water, because intermediate reaction products had not only $Co(OH)_2$ but also sodium sulphate ($Na_2SO_4$), as an impurity. Then the cobalt powder was synthesized by diethylene glycol (DEG), as a reduction agent, with various temperatures and times. Polyvinylpyrrolidone (PVP), as a capping agent, was also added to control agglomeration and dispersion of the cobalt nano particles. The optimized synthesis condition was achieved at $220^{\circ}C$ for 4 hours with 0.6 of the PVP/$Co(OH)_2$ molar ratio. Consequently, it was confirmed that the synthesized nano sized cobalt particles had a face centered cubic (fcc) structure and with a size range of 100-200 nm.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.19.1-19.1
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• 2007

• 한국재료학회:학술대회논문집
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• 한국재료학회 2002년도 추계학술발표강연 및 논문개요집
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• pp.144-144
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• 2002