• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1663-1670
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• 2006

Single crystal Fe thin films were grown directly onto n-Si(111) substrates by pulsed electrodeposition. Cyclic Voltammogram(CV) indicated that the $Fe^{2+}/n-Si(111)$ interface shows a good diode behavior by forming a Schottky barrier. From Mott-Schottky (MS) relation, it is found that the flat-band potential of n-Si(111) substrate and equilibrium redox potential of $Fet^{2+}$ ions are -0.526V and -0.316V, respectively. The nucleation and growth kinetics at the initial reaction stages of Fe/n-Si(111) substraste was studied by current transients. Current transients measurements have indicated that the deposition process starts via instantaneous nucleation and 3D diffusion limited growth. After the more deposition, the deposition flux of Fe ions was saturated with increase of deposition time. from the as-deposited sample obtained using the potential pulse of 1.4V and 300Hz, it is found that Fe nuclei grows to three dimensional(3D) islands with the average size of about 100nm in early deposition stages. As the deposition time increases, the sizes of Fe nuclei increases progressively and by a coalescence of the nuclei, a continuous Fe films grow on the Si surface. In this case, the Fe films show a highly oriented columnar structure and x-ray diffraction patterns reveal that the phase ${\alpha}-Fe$ grows on the n-Si(111) substrates.

• Resources Recycling
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• v.31 no.1
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• pp.12-20
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• 2022

The smelting reduction of spent lithium-ion batteries results in metallic alloys containing Co, Cu, Fe, Mn, Ni, and Si. A process to separate metal ions from the sulfuric acid leaching solution of these metallic alloys has been reported. In this process, ionic liquids are employed to separate Fe(III) and Cu(II). In this study, D2EHPA and Cyanex 301 were employed to replace these ionic liquids. Fe(III) and Cu(II) from the sulfate solution were sequentially extracted using 0.5 M D2EHPA with three stages of cross-current and 0.3 M Cyanex 301. The stripping of Fe(III) and Cu(II) from the loaded phases was performed using 50% (v/v) and 60% (v/v) aqua regia solutions, respectively. The mass balance results from this process indicated that the recovery and purity percentages of the metals were greater than 99%.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.13-17
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• 2010

Fe-3, 4.2 and 6.8% Si compressed cores were fabricated, and then electrical resistivity, AC and DC magnetic properties, microhardness, and other properties were analyzed in order to know whether best soft magnetic properties could be also obtained in an Fe-Si compressed core with the well-known composition of Fe-6.5% Si. With increasing the silicon content, eddy current loss and hysteresis loss decreased and increased, respectively, so that a minimum total loss was not obtained in the well-known Fe-6.8 % Si cores, but obtained in the Fe-4.2 % Si cores. Also electrical resistivity of the cores and hardness of the particles increased monotonously with silicon content so that compaction ratio of the cores decreased. B2 and $DO_3$ ordered phase could be observed only in Fe-6.8% Si powder. A minimum loss and highest permeability of the Fe-4.2 % Si cores can be explained by the ratio of specific electrical resistivity of insulator to that of magnetic particles, micro-hardness, compaction ratio and demagnetization coefficient of the Fe-Si powder particles with silicon content.

• Journal of the Korean Magnetics Society
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• v.13 no.4
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• pp.171-175
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• 2003

Electron paramagnetic resonance (EPR) of Fe$^{3+}$ in LiTaO$_3$ single crystal, grown by Czochralski method, has been studied by employing an X-band spectrometer. Resonance spectra of Fe$^{3+}$ ion on the crystallographic principal axes were obtained with 9.447 ㎓ at room temperature. The spectroscopic splitting parameter g and zero-field splitting (ZFS) parameter D (= 3 B$_{2}$sup 0/) are calculated with effective spin Hamiltonian. Fe$^{3+}$ center in stoichometric single crystal turns out to be different with that in congruent single crystal reported previously. From the analysis of temperature dependence of resonance fields for Fe$^{3+}$ ion, there is no any phase transition at the temperature range (from -160 $^{\circ}C$ to 20 $^{\circ}C$).

• Korean Journal of Materials Research
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• v.13 no.1
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• pp.48-52
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• 2003

The substituted yttrium iron garnet systems $Y_{ 3-x}$/Gd$_{x}$X$0.2_{0.2}$ $Fe_{4.8}$ $O _{12}$ (x = 0.2, 0.4, 0.6) have been investigated by means of X-ray diffraction, Mossbauer spectroscopy and SQUID. The X-ray diffraction patterns at room temperature confirm the samples to have a single phase of the garnet structure over the whole composition range. The lattice constants of all the samples linearly change with increasing x due to the size of substituted ions in the dodecahedral sites. $Y_{3-x}$ $Gd_{x}$ X$Fe_{4.8}$ $In_{0.2}$ $O_{12}$ system which $Y_{3-x}$ ions are substituted with Gd$^{ 3＋}$ ions, the Mossbauer spectrum consists of three Zeeman sextets at room temperature, one due to the $Fe^{3＋}$ ions on the octahedral(a-) sites and the others due to the $Fe^{3＋}$ ions on the tetrahedral(d-, d'-) sites, respectively. From the hysteresis loop measured by means of SQUID over the whole composition range, the saturation magnetization $M_{s}$ and magnetic moments $\mu_{ B}$ per unit cell have been obtained. The increment of Gd-ion content causes $M_{s}$ and $\mu_{B}$ decrease while the increment of In-ion content does not.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.697-702
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• 2011

The new layered perovskite manganites $La_{0.5}Sr_{1.5}Mn_{0.5}Cr_{0.5-x}Fe_xO_4$ (x=0.15, 0.3) have been prepared by standard ceramic method. The powder X-ray diffraction studies show that the phases crystallize with tetragonal unit cell in the space group I4/mmm. The electrical transport properties suggest that the phases show insulating behaviour and the electrical conduction in the phases occurs by a 3D variable range hopping mechanism. The magnetic properties suggest that both the phases are antiferromagnetic.

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.730-733
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• 1997

Monofluoroiron(Ⅲ) tetraphenylporphyrin, Fe(TPP)F, and difluoroiron(Ⅲ) tetraphenylporphyrin, [Fe(TPP)F2]- were generated in a various non-aqueous solvents by the reaction between Fe(TPP)Cl and tetrabutylammonium fluoride TBAF 3H2O. Formation of the these complexes was detected by the appearance of the ν(F-Fe) (ν, stretching vibration) at 506 cm-1 for Fe(TPP)F and the ν(F-Fe-F) at 448 cm-1 for [Fe(TPP)F2]-, simultaneously, with 441.6 nm excitation by Resonance Raman (RR) spectroscopy. These assignments were confirmed by observed frequency shifts due to 56Fe/54Fe and TPP/TPP-d8/TPP-N15 isotopic substitutions. Difluoroiron complex is an iron(Ⅲ) high-spin complex with the oxidation sensitive band at 1347 cm-1 for ν4 and core size/spin state sensitive band at 1541 cm-1 for ν2.

• Nuclear Engineering and Technology
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• v.42 no.5
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• pp.590-599
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• 2010

Recently, efficient operation and practical management of power plants have become important issues in the nuclear industry. In particular, typical aging parameters such as stress and cumulative usage factor should be determined accurately for continued operation of a nuclear power plant beyond design life. However, most of the major components have been designed via conservative codes based on a 2-D concept, which do not take into account exact boundary conditions and asymmetric geometries. The present paper aims to suggest an effective fatigue evaluation methodology that uses a prototype of the integrated model and its transfer functions. The validity of the integrated 3-D Finite Element (FE) model was proven by comparing the analysis results of individual FE models. Also, mechanical and thermal transfer functions, known as Green's functions, were developed for the integrated model with the standard step input. Finally, the stresses estimated from the transfer functions were compared with those obtained from detailed 3-D FE analyses results at critical locations of the major components. The usefulness of the proposed fatigue evaluation methodology can be maximized by combining it with an on-line monitoring system, and this combination, will enhance the continued operations of old nuclear power plants.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.1-8
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• 2017

Fe-9.8Si-6.0Al mother alloy was manufactured using by Fe-3.5Si recycled scrap and Si powder. And then, soft magnetic alloy powder of $D_{50}$ size and sphere type were prepared by gas atomization process. To obtain the soft magnetic powder of a high aspect ratio, in the first, we conducted the ball milling process for 8 hours. And heat treatment was performed under $650^{\circ}C$, 2 hours and $N_2$ atmosphere condition for reducing the residual stress of the powder. Based on these process, we made around $50{\mu}m$ diameter Fe-9.8Si-6.0Al powder, which morphology and shape was a similar to the commercial Fe-Si-Al powder. Finally, the soft magnetic sheets were prepared by tape casting process using by those powders. The permeability of the tape casting sheet was measured, and we confirmed the possibility of reusing to the soft magnetic materials of Fe-Si electric sheet scrap.

• Journal of Powder Materials
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• v.16 no.5
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• pp.336-341
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• 2009

To produce alloy powders with only Sm$_2$Fe$_{17}$ single phase by reduction-diffusion (R-D) method, the effect of excess samarium oxide on the preparation of Sm-Fe alloy powder during R-D heat treatment was studied. The quantity of samarium oxide was varied from 5% to 50% whereas iron and calcium were taken 0% and 200% in excess of chemical equivalent, respectively. The pellet type mixture of samarium, iron powders and calcium granulars was subjected to heat treatment at 1100$^{\circ}C$ for 5 hours. The R-D treated pellet was moved into deionized water and agitated to separate Sm-Fe alloy powders. After washing them in deionized water several times, the powders were washed with acetic acid to remove the undesired reaction products such as CaO. By these washing and acid cleaning treatment, only 0.03 wt% calcium remained in Sm-Fe alloy powders. It was also confirmed that the content of unreacted $\alpha$-Fe in Sm$_2$Fe$_{17}$ matrix gradually decreased as the percentage of samarium oxide is increased. However, there was no significant change above 40% excess samarium oxide.