• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.971-972
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• 2006

Mechanochemical synthesis of zinc ferrite, $ZnFe_2O_4$, was attempted from a powder mixture of iron (III) oxide, alpha-$Fe_2O_3$ and zinc (II) oxide, ZnO. Nanocrystalline zinc ferrite, $ZnFe_2O_4$ powders were successfully synthesized only bymilling for 30 hours. Evidence of the $ZnFe_2O_4$ formation was absent for the powders milled for 10 and 20 hours; the milling lowered the crystallinity of the starting materials. Heating after milling enhanced the formation of $ZnFe_2O_4$, crystal growth of $ZnFe_2O_4$ and the unreacted starting materials. The unreacted starting materials decreased their amounts by heating at higher temperatures.

• 한국전기전자재료학회논문지
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• 제32권4호
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• pp.341-348
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• 2019

This paper reports the microstructure and electrochemical properties of Si-Al-Fe ternary amorphous alloys prepared by rapid solidification as an anode for lithium secondary batteries. The microstructure was analyzed using XRD and HR-TEM with EDS mapping. In accordance with DSC analysis, annealing was performed to crystallize the active nano-Si in the amorphous alloy. Thus, nano-Si forms (~80 nm) embedded in the matrix alloy, such as $Fe_2Al_3Si_3$, $FeSi_2$, and $Fe_{0.42}Si_{2.67}$, were successfully synthesized. The electrode based on the Si-Al-Fe ternary alloy delivered an initial discharge capacity of approximately $700mAh^{g-1}$, and exhibited a high Coulombic efficiency of 99.0~99.6% from the $2^{nd}$ to $70^{th}$ cycles.

• 대한금속재료학회지
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• 제49권9호
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• pp.715-719
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• 2011

Nanopowders of $Fe_3N$ and Si were fabricated by high-energy ball milling. A dense nanostructured $12Fe-Si_3N_4$ composite was simultaneously synthesized and consolidated using a high-frequency induction-heated sintering method for 2 minutes or less from mechanically activated powders of $Fe_3N$ and Si. Highly dense $12Fe-Si_3N_4$ with a relative density of up to 99% was produced under simultaneous application of 80 MPa pressure and the induced current. The microstructure and mechanical properties of the composite were investigated.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 동계연구발표회 논문개요집
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• pp.214-215
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• 2002

High saturation magnetization (B$\_$s/) and excellent high frequency characteristics of magnetic thin films has been recognized as the most important requirement for further miniaturization and higher frequency operation in magnetic devices, such as magnetic heads and magnetic sensors. Up to now, Fe-X-N (X =Ti, Hf, and Al etc.) films with B$\_$s/ of 15 ∼ 19 kG and coercivity (H$\_$c/) of 0.5 ∼ 5.0 Oe have been successfully fabricated and proven to satisfy various requirements as a potential candidate for thin film head materials. (omitted)

• 한국세라믹학회지
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• 제48권5호
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• pp.454-457
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• 2011

We report the preparation of nanocrystalline cobalt ferrite, $CoFe_2O_4$, particles using recycled $Co_3O_4$ and their surface coating with silica using micro emulsion method. Firstly, the $Co_3O_4$ powders were separated from waste cemented carbide with acid-base chemical treatment. The cobalt ferrite nanoparticles with the size 10 nm are prepared by thermal decomposition method using recycled $Co_3O_4$. $SiO_2$ was coated onto the $CoFe_2O_4$ particles by the micro-emulsion method. The $SiO_2$-coated $CoFe_2O_4$ particles were studied their physical properties and characterized by X-ray diffraction (XRD), high resolution-transmission electron microscopy (TEM) analysis and CIE Lab value.

• 한국자기학회지
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• 제5권5호
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• pp.641-644
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• 1995

We have studied the effect of the nitrogen on the microstructure, thermomagnetic properties and corrosion resistance of Fe-Hf-C-N nanocrystalline thin films with high permeability and high saturation magnetization. These films were fabricated by reactive sputtering in $Ar+N_{2}$ plasma using an rf magnetron sputtering apparatus. As $P_{N2}$ increases, the microstructure changes from amorphous to crystalline $\alpha$-Fe phase and again returns to amorphous one. Spin wave stiffness constant increases with $P_{N2}$ until 5% $P_{N2}$, and then decreases with the further increase. This trend corresponds well with that of the microstructure with increasing $P_{N2}$. The Fe-Hf-C-N films with over 3% $P_{N2}$ show higher corrosion resistance than the N-free Fe-Hf-C films. The Fe-Hf-C-N films are considered to have high potentials for the head core materials suitable for high density recording systems, owing to their excellent soft magnetic properties and corrosion resistance.

• 대한화학회지
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• 제68권2호
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• pp.82-86
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• 2024

This paper presents the solid-state synthesis of insoluble Prussian blue (Fe₄[Fe(CN)₆]₃·xH₂O, PB) in a ball mill, utilizing the fundamental components of PB. Solid-state synthesis offers several advantages, such as being solvent-free, quantitative, and easily scalable for industrial production. Traditionally, the solid-state synthesis of PB has been limited to the reaction between iron(II/III) ions and hexacyanoferrate(II/III) complex ions, essentially an extension of the solution-based coprecipitation method to solid-state reaction. Taking a bottom-up approach, a reaction is designed where the reactants consist of the basic building blocks of PB: Fe²⁺ ions and CN^- ions. The reaction, with a molar ratio of Fe²⁺ and CN^- corresponding to 1:2.8, yields PB, while a ratio of 1:6.6 results in a mixture of potassium hexacyanoferrate(II) (K₄Fe(CN)₆), potassium chloride (KCl), and potassium cyanide (KCN). This synthetic approach holds promise for environmentally friendly methods to synthesize multimetallic PB with maximum entropy in nearly quantitative yield.

• 한국자기학회지
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• 제5권1호
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• pp.38-41
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• 1995

$\alpha$-Fe를 주상으로 하는 새로운 Nd-Fe-B계 합금을 개발하기 위하여 Nd 함유량을 4at.%로 고정시킨 Nd-Fe-B 초미세결정립합금의 제조 및 자기특성이 조사되었다. 급속응고법으로 제조된 $Nd_{4}Fe_{85.5}B_{10.5}$ 비정질합금은 결정화하여 $\alpha$-Fe 기지상에 $Nd_{2}Fe_{14}B$이 형성되나 자기특성${_{i}H_{c}=95.5kA/m(1.2kOe),\;Br=1.2T}$은 열화된다. Nb 및 Cu를 첨가한 $Nd_{4}Fe_{82}B_{10}Nb_{3}Cu_{1}$ 합금은 $\alpha$-Fe 결정립미세화(<30nm)로 보자력이 207kA/m(2.6 kOe)로 증가하나 잔류자화는 개선되지 않았다. 이 합금조성에 8at.% Co 첨가는 결정립을 더욱 미세화시키며 자기특성을 개선 시킨다. 최적열처리조건에서 $Nd_{4}Fe_{74}Co_{8}B_{10}Nb_{3}Cu_{1}$ 합금의 잔류자화, 보자력 및 최대에너지적이 각각 1.34 T, 219 kA/m (2.75kOe) 및 $95.5kJ/m^{3}$(12MGOe) 이다.

• Journal of Magnetics
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• 제11권4호
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• pp.167-169
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• 2006

Nanocrystalline CoFeHfO thin films have been fabricated by RF sputtering method. It is shown that the CoFeHfO thin films possess not only high electrical resistivity but also large saturation magnetization and anisotropy field. Among the composition investigated, $Co_{53}FE_{22}Hf_{10}O_{15}$ thin film is observed to exhibit good soft magnetic properties: coercivity ($H_{c}$) of 0.18 Oe; anisotropy fild ($H_{k}$) of 49.92 Oe; saturation magnetization ($4{\Pi}M_{s}$) of 15.5 kG. The frequency response of permeability of the film is excellent. The excellent magnetic properties of this film in addition of an extremely high electrical resistivity (r) of $185\;{\mu}cm$ make it ideal for uses in high-frequency applications of micromagnetic devices. It is the formation of a peculiar microstructure that resulted in the superior properties of this film.

• Journal of Magnetics
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• 제21권2호
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• pp.164-167
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• 2016

The effect of the B additions on glass formation and magnetic properties is reported for the $Fe_{(87-x-y)}Co_yTi_7Zr_6B_x$ (x = 2, 4, 6 and y = 35, 40) alloy system. The ribbon samples with the width of 2 mm for each composition were prepared by the melt spinning technique; furthermore, their phase information was obtained from X-ray diffraction. Glass formation and magnetic properties were measured using differential scanning calorimetry and vibrating sample magnetometer respectively. The $Fe_{45}Co_{40}Ti_7Zr_6B_2$ (x = 2 and y = 40) system has the nanocrystalline phase identified as ${\alpha}-Fe$, as well as the amorphous phase, whereas all other alloys are fully amorphous. It is associated with the role of B on the glass formation. The widest supercooled liquid region is obtained as 71 K at x = 4 (both y = 35 and 40). The saturation magnetization decreases with the increase of the amount of the B addition, and the highest value is 1.59 T as x = 2 and y = 35 for this alloy system.