• Journal of the Korean Magnetics Society
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• v.16 no.5
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• pp.249-254
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• 2006

CoFeNi alloys are some of the most studied soft magnetic materials because of their superial properties over FeNi alloys as write head core materials in HDD and MEMS. We studied the effect of magnetic property according to size and orientation of crystal for electroplated Co-Fe-Ni alleys. In case of heat treated ternary alloy, it affect the change of crystal size and structure. In this study, it intends to improve the magnetic properties of CoFeNi thin film by heat treatment. Minimized coercivity and increased magnetization are due to heat treatment from $300^{\circ}C\;to\;400^{\circ}C$. As a bcc phase formation, it grow to amount of magnetization.

• Korean Journal of Materials Research
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• v.9 no.10
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• pp.1037-1040
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• 1999

Magnetic characteristics of some anisotropic mischmetal- FeB- (Co,Ti,Al) permanent magnets have been investigated. The magnets were fabricated by using hot-pressed and die-upsetting. Hot-pressed $\textrm{(MM)}_{12.5}\textrm{Fe}_{71.9}\textrm{Co}_{5.0}\textrm{Al}_{2.0}\textrm{B}_{8.6}$ permanent magnet showed $\textrm{H}_{c}$=4.27 kOe, $\textrm{B}_{r}$=4.75 kG, $\textrm{(BH)}_{max}$=3.82 MGOe, and die- upset magnet showed $\textrm{H}_{c}$=3.10 kOe, $\textrm{B}_{r}$=5.58 kG, $\textrm{(BH)}_{max}$=5.34 MGOe, respectively. Hot-pressed $\textrm{(MM)}_{12.5}\textrm{Fe}_{77.9}\textrm{Ti}_{1.0}\textrm{B}_{8.6}$ permanent magnet showed $\textrm{H}_{c}$=3.75 kOe, $\textrm{B}_{r}$=4.64 kG, $\textrm{(BH)}_{max}$=2.78 MGOe, and die- upset magnet showed $\textrm{H}_{c}$=3.29 kOe, $\textrm{B}_{r}$=5.01 kG, $\textrm{(BH)}_{max}$=3.54 MGOe, respectively. X-ray diffraction and transmission electron microscopy revealed that the higher energy products in the die-upset magnets results from alignment of the c-axis along the die-upsetting direction. The magnetic anisotropy in hot-pressed MM-FeB- Al magnet is increased by the substitution of Co for Fe.

• Applied Microscopy
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• v.45 no.1
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• pp.32-36
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• 2015

The microstructural features of FeCoCrNi, FeCoCrNiAl and FeCoCrNiSix (x=0, 5, 10, 15, 20) alloys have been investigated in the present study. The microstructure of FeCoCrNi alloy changes dramatically with equiatomic addition of Al. The fcc irregular shaped grain structure in the as-cast FeCoCrNi alloy changes into the bcc interconnected structure with phase separation of Al-Ni rich and Cr-Fe rich phases in the as-cast FeCoCrNiAl alloy. The microstructure of FeCoCrNi alloy changes with the addition of Si. With increasing the amount of Si, the fcc structure of the grains is maintained, but new phase containing higher amount of Si forms at the grain boundary. As the amount of Si increases, the fraction the Si-rich grain boundary phase increases.

• Bulletin of the Korean Chemical Society
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• v.13 no.5
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• pp.542-546
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• 1992

New silicon-monosubstituted (${\eta}^4$-2,3,4,5-tetraphenyl-1-silacyclopentadiene)transi tion metal complexes are described. The new (silole-transition metal complex)Fe$(CO)_3$ was obtained from the reaction of silole-tansition metal complex and Fe$(CO)_5$. We have determined the crystal structure of (${\eta}^4$-exo-cyclopentadienyldicarbonyliron-endo-1-meth yl-2,3,4,5-tetraphenyl-1-silacyclopentadienyl)tric arbonyliron by using graphitemonochromated Mo-$K_{\alpha}radiation. The compound was crystallized in the monoclinic space group $P2_1$/c with a = 8.925(1), b = 18.689(3), c = 19.930(3) ${\AA}$, and ${\beta}$ = 102.02$(1)^{\circ}$. The iron moiety CpFe$(CO)_2$ on silicon is in an axal position. The (silole-transition metal complex) Fe$(CO)_3$ was also prepared through the reaction of (${\eta}^4$-1-chloro-2,3,4,5-tetraphenylsilacyclopentadiene) Fe$(CO)_3$ and metal complex nucleophile. The structure configuration was studied by conventional spectroscopy.

• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.111-120
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• 1985

The oxidation reaction of CO on the catalysts 4 mol%, 8 mol%, and 12 mol% Cd-doped ${\alpha}-Fe_2O_3$ is individually investigated. Regardless of Cd doping level, over-all reaction order for the oxidation of CO is 1.5; the first order with respect to CO and the one-half order with respect to $O_2$. Over the temperature range of 350∼$460^{\circ}C$, the activation energy for CO oxidation is 10.10∼11.30Kcal/mol. From the agreement between the kinetic data and conductivity measurements, the reaction mechanism is suggested. Especially from the effect of Cd doping, the fact that catalytic activity of ${\alpha}-Fe_2O_3$ is due to the excitation of electrons which are traped on oxygen vacancy is found, and the adsorption sites for reactant molecules are found.

• Journal of the Korean institute of surface engineering
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• v.28 no.6
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• pp.352-360
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• 1995

The effect of electrolysis conditions on the composition, the magnetic properties and the preferred orientation of Ni-Fe-Co alloy deposits was investigated using the sulfate-chloride bath paddle agitated. Cathode current efficiency increases with the current density, showing the different tendency of the variation from that of the Ni-Fe electrodeposits. The Co content of the deposits decreases with increasing current density, while the content of Ni and Fe is shown to be minimum or maximum at 3A/$dm^2$ respectively. The Ni/Fe ratio of the alloy deposits is lower than that of Ni-Fe deposits. The coercive force($H_c$) of the deposits increases with the Co content in deposit, showing the relatively low value in the range of 1.8~5.0Wt.% Co. The anisotropy field ($H_k$) of the deposits is higher than that of Ni-Fe alloy deposits, The preferred orientation of the deposits is generally (200), but the orientation factor(R) changes with both the increase of current density and the magnetic field applied during deposition.

• Journal of Powder Materials
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• v.10 no.5
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• pp.305-309
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• 2003

We report on the formation and chemical leaching of non-equilibrium $Al_{0.6}(Fe_{75}Co_{25})$ alloy produced by rod milling. X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry, scanning electron microscopy, and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h, only the $Al_{0.4}Fe_{0.6}$ peak of the body-centered cubic type was present in the XRD pattern. The entire rod milling process could be divided into three different stages of milling: agglomeration, disintegration, and homogenization. The saturation magnetization, $M_s$ decreased with increased milling time, the $M_s$ of the powders before milling was about 113.8 emu/g, the $M_s$ after milling for 400 h was about 11.55 emu/g. Leaching of the Al in KOH of the Al at room temperature from the as-milled powders did not induce any significant change in the diffraction pattern. After the leached specimen had been annealed at $600^{\circ}C$ for 1 hour, the nanoscale crystalline phases were transformed into the bcc Fe, cubic Co, and $CoFe_2O_4$ phases. On cooling the specimen from 85$0^{\circ}C$, the degree of magnetization increased slightly, then increased sharply at approximately 364.8$^{\circ}C$, indicating that the bcc $Al_{0.4}Fe_{0.6}$ phase had been transformed to the Fe and Co phases.

• Electrical & Electronic Materials
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• v.5 no.1
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• pp.8-13
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• 1992

일련의 Al/Tb-Fe-Co 다층박막 시편이 DC마그네트론 스퍼터링에 의해 제조되었다. 이 박막들은 (xA/yB)n의 형태이고 여기서 x와 y는 각각 Al 및 Tb-Fe-Co 박막의 두께를 나타내고 n은 각 박막의 수를 나타낸다. 각 박막의 두께는 2~40nm이다. Al과 Tb-Fe-Co박막의 두께변화에 따른 다층박막의 자기적 성질이 vibration sample magnetometry(VSM)에 의해 측정되었다. 이들 다층박막은 동일한 스퍼터링조건에서 제조되고 수평 자기적 이방성 특성을 보이고 있는 단층 Tb-Fe-Co박막을 기준시편으로 하여 자기적 성질이 비교되었다. 다층박막 시스템에서는 현저한 계면 또는 박막두께의 효과가 발견되었으며 이들 효과에 의해 단층박막의 수평자기체가 다층박막에서는 강한 수직자기체로 변화되는 것을 알 수 있고, 또한 Al과 Tb-Fe-Co합금 경계구역에 스퍼터링에 따른 약 2nm두께의 dead layer가 존재함이 입증 되었다.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.1-5
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• 2006

The crystallographic properties and cation distribution of oxyspinels ferrite $Co_xFe_{1-x}O_4$ thin films have been explored by X-ray diffraction, vibrating sample magnetometer (VSM), and conversion electron $M\"{o}ssbauer$ spectroscopy (CEMS). Thin films are prepared by sol-gel method. Normal spinel structure is transformed to inverse spinel structure with increasing Co concentration CEMS results indicate that most of $Fe^{3+}$ ions are substituted to $Co^{3+}$ions. Accordingly $Co^{2+}$ ions on octahedral site migrate to tetrahedral site. Magnetic moment is decreased with increasing Co concentration, which means high spin $Fe^{3+}$ ions are replaced by low spin $Co^{3+}$.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.332-334
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• 1991

The reaction and coordination chemistry of chiral ferrocenylaminophosphines such as 2-(diphenylphosphino)-1-(N,N-dimethylaminoethyl) ferrocene (PPFA), and 1',2-bis(diphenylphosphino)-l-(N,N-dimethylaminoe thyl) ferrocene (BPPFA), with various iron carbonyls have been investigated. PPFA reacted with iron carbonyls, Fe$(CO)_5$, $Fe_2(CO)_9$, or $Fe_3(CO)_{12}$ to give an iron complex of the type (${\eta}^1$-PPFA-P)Fe$(CO)_4$ (1) as a single product regardless the choice of the iron carbonyls. The bisphosphine ligand BPPFA afforded two products (${\eta}^1$-BPPFA-P)Fe$(CO)_4$ (2) and (${\mu}$,${\eta}^1$-BPPFA-P,P)$Fe_2(CO)_8$ (3) in which BPPFA acts as a monodentate and a bridging ligand, respectively. In all cases coordination to the -Fe$(CO)_4$ moiety is made through the phosphine rather than the amino group and, in the case of 2, the coordination is made through the phosphine substituted at the $C_5H_4$ ring to reduce the steric congestion.