• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.64-65
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• 2002

Recently the synthetic antiferromagnetic layer (SAF) has received much attention because it replaces the pinned layer of the conventional spin valve (CSV) sensors and its overall performance [1], The spin valve (SV) with SAF has the from buffer/F/Cu/APl/Ru/AP2/AF, where F is the soft ferromagnetic layer (typically NiFe with CoFe interfacial doping), AP1 and AP2 are two ferromagnetic layers (typically CoFe alloys) antiferromagnetically coupled through a thin Ru layer. (omitted)

• Journal of the Korean Magnetics Society
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• v.14 no.6
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• pp.224-227
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• 2004

We have studied local magnetization reversal by laser annealing in exchange biased NiFe/FeMn bilayer. Local magnetization reversal was performed by using the DPSS laser under external magnetic field of 600G. When the laser illuminated the patterned film with the power of above 300 mW during 15 min, a magnetoresistance (MR) curve with symmetric peaks at the opposite field was obtained due to the local reversal of exchange biasing. The direction of exchange anisotropy in the locally reversed region can be restored by local laser annealing under alternating magnetic field, even if its MR peak was reduced by the damage and interdiffusion. The magnetic domain structure of the locally reversed region was measured by MFM. The new domains were generated by laser annealing near the exposed area.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.85-92
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• 2011

Evaluation of the removal efficiencies of Fe(II) by reactive sand media coated with manganese (MCS), iron (ICS) and both of iron and manganese (IMCS) was investigated as functions of solution pH ranging from 2 to 9, reaction time and concentration of Fe(II) in a batch reactor using each reactive medium and additional oxidants such as $KMnO_4$ and NaOCl. When only Fe(II) was present in solution without any reactive medium, removal of Fe(II) was quite low below pH 5 due to a slow oxidation of Fe(II) and/or negligible precipitation but greatly increased above pH 5 due to a rapid oxidation of Fe(II) and subsequent precipitation of oxidized Fe species. ICS showed negligible efficiency on the removal of Fe(II) through adsorption. However, an efficient removal of Fe(II) was observed at low solution pH in the presence of IMCS or MCS through rapid oxidation and subsequent precipitation. Removal efficiency of Fe(II) by IMCS in the presence or absence of NaOCl was quite similar. Removal rate of Fe(II) by IMCS and additional oxidants gradually increased as the solution pH increased. From the kinetic experiments, removal pattern of Fe(II) was better described by pseudo-second-order equation than pseudo-first-order equation. A rapid removal of Fe(II) using IMCS in the presence of $KMnO_4$ was observed in the first 10 min. The initial removal rate of Fe(II) using $KMnO_4$ was 14,286 mg/kg hr. In case of using NaOCl, the removal of Fe(II) occurred rapidly in the first 6 hrs and then reached the near-equilibrium state. Removal of Fe(II) on IMCS was well expressed by Langmuir isotherm and the maximum removal capacity of Fe(II) was calculated as 1,088 mg/kg.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.312-316
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• 1999

The interfacial structure of duplex treated AISI 4140 consisting of iron nitride and TiN layer was characterized by optical microscope, SEM and XRD. A black layer was formed from the decomposition of iron nitride during Ti ion bombardment. The black layer was characterized as an a-Fe phase transformed from the iron nitride by XRD. In order to identify the formation mechanism of the black layer, a thermal analysis of iron nitride undertaken by DSC method. As an iron nitride was mostly consisted of ${\gamma}$'-Fe$_4$N and $\varepsilon$-$Fe_3$N phase after plasma nitriding, in this study, a ${\gamma}$'$-Fe_4$N and $\varepsilon$-$Fe_3$N powders were separately prepared by the different processing conditions of gas nitriding of iron powder in the fluidized bed. From the DSC thermal analysis, the phase transformation of ${\gamma}$'$-Fe_4$N, $\varepsilon$-$Fe_3$N was followed the path of transformation; $ \Upsilon{'}-Fe_4$Nlongrightarrow${\gamma}$-Felongrightarrowa-Fe and of $\varepsilon$-$Fe_3$Nlongrightarrow$\varepsilon$-$Fe_{2.5}$ /N+${\gamma}$'$-Fe_4$Nlongrightarrow${\gamma}$'-Fe$_4$Nlongrightarrow${\gamma}$longrightarrowFelongrightarrowalongrightarrowFe, respectively. It explains the reason why the $\varepsilon$ $-Fe_3$N phase disappeared in the first time and then ${\gamma}$'-Fe$_4$N in the formation of the black layer in the duplex coating.

• Corrosion Science and Technology
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• v.13 no.4
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• pp.145-151
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• 2014

The objectives of this study are to investigate the effect of the concentration ratios of Ni and Fe ions on crud deposition onto the fuel cladding surface in the simulated primary environments of a pressurized water reactor. Crud deposition tests were conducted in the Ni and Fe concentration ratios of 20:20 ppm, 39:1 ppm and 1:39 ppm at $325^{\circ}C$ for 14 days. In the case of the same Ni and Fe ion ratio (20:20), nickel ferrite with a polyhedral shape was formed. Nickel oxide deposits with a needle shape were formed in the condition of high Ni to Fe ion ratio (39:1), While polyhedral iron oxide and needle-like nickel oxide formed in the condition of low Ni to Fe ion ratio (1:39). The amount of deposits increased, when Fe oxides were formed. This indicates that Fe rich oxides stimulated Ni oxide deposition.

• Journal of the Korean Chemical Society
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• v.44 no.4
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• pp.311-315
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• 2000

The Fe(II)-isothiocyanato complex $trans-[FeH(NCS)(dppe)_2]$ (1) eactedwith iodomethane(Mel) to give methyl isothiocyanide-Fe(n) complex, $trans-FeH(NCS(Me)-S)(dppe)_2]I(2)$. Compound 2 was oxidized to $trans-[Fe(NCS)_2(Ph_2P(O)CH_2CH_2P(O)Ph_2)_2][I_3]$ (3), which was structurally characterized by X-ray diffraction. The molecular structure of 3 showed a bent Fe-NCS group, Crystallographic data for 3: triclinic space group P1,a=11.071(2) A,b=12.054(2)A,c=12.121(1)A, $\alpha=101.02(1){\circ}C{\beta}=95.887(9){\circ}Cr=110.34(1){\circ}C$, $Z=1R(wR_2)=0.0567(0.1294)$.

• Journal of the Korean earth science society
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• v.25 no.1
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• pp.48-51
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• 2004

The light element candidates such as S, O, Si, and K are discussed for the reasonable compositions in the earth's core since the available data show density difference from pure iron core. These candidates are favored by the some evidences such as depletion in the crust and mantle, and lower eutectic temperature of Fe-FeS melt for sulfur. FeO phase for oxygen, lighter mass than sulfur and solubility in metallic phases for silicon, and partitioning in Fe-FeS melt for potassium. However, other problems such as short experimental data, initial compositions of these elements, and oxidation state during the formation of the earth should be solved simultaneously to confirm these light elements.

• Journal of the Korean Magnetics Society
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• v.23 no.2
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• pp.43-48
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• 2013

The Jahn-Teller distortion of chalcogenide $Fe_{0.9}M_{0.1}Cr_2S_4$ (M=Co, Ni, Zn) have been investigated by M$\ddot{o}$ssbauer spectroscopy. The crystal structures of $Fe_{0.9}M_{0.1}Cr_2S_4$ (M=Co, Ni, Zn) are cubic spinel at room temperature. Magnetoresistance measurements indicate these system is conducting-semiconducting transistion around $T_C$. Below $T_C$, the asymmetric line broadening is observed and considered to be dynamic Jahn-Teller distortion. Isomer shift value of the samples at room temperature was about 0.5 mm/s, which means that charge state of Fe ions is ferrous in character. The Ni substitutions for Fe occur to increase the Jahn-Teller relaxation. CMR properties could be explained with magnetic polaron due to Jahn-Teller effect, which is different from both the double exchange interactions of manganite system and the triple exchange interactions of chalcogenide $Cu_xFe_{1-x}Cr_2S_4$.

• Journal of Magnetics
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• v.16 no.2
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• pp.97-100
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• 2011

Bilayers of soft NiFe (150 nm-420 nm) on hard Ni (150 nm) were prepared by electrodeposition. The process of magnetization reversal in the NiFe/Ni bilayers was then investigated. The hysteresis loop generated by a magnetization reversal of soft NiFe under a positive saturation state of a hard Ni layer shows a shift along the negative field axis, which is clear evidence for the exchange spring effect in the NiFe/Ni bilayers. The dependence of the coercive field $H_c$ and exchange bias field Hex on the thickness of the NiFe layer was also investigated. As the NiFe thickness increases from 150 nm to 420 nm, both $H_c$ and $H_{ex}$ decrease rapidly from $H_c$= 51.7 Oe and $H_{ex}$ = 12.2 Oe, and saturate to $H_c$ = 5.8 Oe and $H_{ex}$ = 3.5 Oe.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.172-176
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• 1998

An anion exchange resin which has Alizarin Red S (ARS) as functional group was prepared by batch method. The resin is stable in acidic solutions below 0.5 M hydrochloric acid, nitric acid and sulfuric acid and adsorption capacity of Fe(Ⅱ) ion on the resin was larger than other metal ions. The preconcentration and the separation of Fe(Ⅱ) ion from the mixture solution were carried out with the pH 4.5 buffer solution and 0.1 M $HNO_{3}$ as eluents.