• Bulletin of the Korean Chemical Society
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• v.27 no.1
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• pp.35-36
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• 2006

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.131.2-131
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• 2002

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.28-29
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• 1997

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.874-879
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• 1995

Magnetic properties of FeMoN, FeMoTaN, FeTaN and FeTaC films deposited by DC magnetron reactive sputter were investigated, and correlated with their microstructure. FeMoN films were not showen the soft magnetic prop¬erties, because of generated $Fe_{2}Mo$, $Fe_{3-2}N$ and $Fe_{4}N$ phases. Ta added films, however, effectivly retarded the $\alpha$-Fe grain growth and suppressed the generation of Fe nitrides or carbides during heat treatement. The soft magnetic properties of $B_{s}:15\;kG,\;H_{e}:0.25\;Oe,\;\mu':4000(at\;5\;MHz),\;and\;B_s:14.5\;kG,\;He:0.25\;Oe,\;\mu':2700(5MHz)$ were observed in $Fe_{78.8} Ta_{8.5}N_{12.7}\;and\;Fe{75.6}Ta_{8.1}C_{16.3}$ films, respectively.

• Journal of the Korean Magnetics Society
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• v.12 no.1
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• pp.34-40
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• 2002

In order to improve the microstructure of the strip cast Nd-Fe-B alloys that are frequently used for production of high energy sintered magnets, influence of various strip casting conditions on the microstructure and phase formation and distribution were investigated. Nd-Fe-B strips consisting of microstructures suitable for preparation of high energy sintered magnets could be obtained when the wheel speed was below 5 m/s. The compositional limit that can avoid the crystallization of free iron in the as-cast state was estimated to be Nd$\_$14/Fe$\_$79/B$\_$7/. Regardless of the compositional variation, <001> preferred orientation of Nd$_2$Fe$\_$14/B normal to the strip surface was always occurred below 5 m/s, which would eventually enhance the grain alignment during pressing the powder under a magnetic field. While the coercivity of the strip cast alloys increased with the increase of the wheel speed, mainly due to the refinement of Nd$_2$Fe$\_$14/B grains, it decreased with the reduction of Nd content in the alloy composition as the formation of free iron increased.

• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.368-376
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• 2009

In this study we investigated and tried to understand problems monitored in an experiment on reactivity of metals in chemistry I. Three problems were discussed. First, the reason that aluminium plate does not react with other metal ions such as zinc, iron and copper was studied and the way to overcome this problem was suggested. Second, the reason that the bubbles were generated when FeS$O_4$(aq) and Zn(s) react was discussed. Third, the precipitates which appeared in the reaction of FeS$O_4$(aq) and Zn(s) were identified. Through reference study and experimental investigation, we could reach the following results. First, aluminium could not react with other metal ions due to the surface oxide layer that is formed very fast and prevents aluminium from reacting with metal ions in solution. This problem could be overcome by allowing a competing reaction of acid and aluminium during the reaction of aluminium and metal ions. Second, the observed bubbles were identified to be hydrogen gas, produced by the reaction between metals and hydronium ion in the solution. Third, black precipitates that were produced on the surface of zinc plate and exhibited magnetic property were characterized to be $Fe_3O_4$(s), and brown precipitates that were produced in the solution phase were to be $Fe_2O_3$(s) by the analysis of X-ray photoelectron spectra.

• Journal of Soil and Groundwater Environment
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• v.27 no.1
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• pp.25-30
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• 2022

Mackinawite (FeS), as a ubiquitous reduced iron mineral, is known as a key controller of redox reactions in anaerobic subsurface environment. The reaction of FeS with redox-sensitive toxic element such as arsenic is substantially affected by pH conditions of the given environments. In this study, the interaction of As(V) with FeS was studied under strict anaerobic conditions with various pH conditions. The pH-dependent arsenic removal tests were conducted under wide ranges of pH conditions and X-ray absorption spectroscopy (XAS) was applied to investigate the reaction mechanisms under pH 5, 7, and 9. The removal efficiency of FeS for As(V) showed the higher removal of As(V) under low pH conditions and its removal efficiency decreased with increasing pH, and no As(V) reduction was observed in 1 g/L FeS solution. However, XAS analysis indicated the reduction of As(V) to As(III) occurred during reaction between FeS and As(V). The reduced form of As(III) was particularly identified as an arsenic sulfide mineral (As₂S₃) in all pH conditions (pH 5, 7, and 9). As₂S₃ precipitation was more pronounced in pH 5 where the solubility of FeS is higher than in other pH conditions. The linear combination fitting results of XAS demonstrated that As(V) removal mechanism is concerted processes of As₂S₃ precipitation and surface complexation of both arsenic species.

• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.138-144
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• 2010

This study was conducted to investigate the effect of Lactobacillus sp. and Saccharomyces sp. on turf quality, shoot and root growth of creeping betgrass in golf course by measuring turf color index, chlorophyll content, dry weight of shoot and root, T/R ratio and root length. Fertilizer treatment was designed as follows; nonfertilizer (NF), control (CF; compound fertilizer), microorganism medium(MO; CF+MO)), microorganism medium contained Fe(MO-Fe; CF+MO-Fe) and microorganisum medium contained S (MO-S; CF+MO-S). Soil properties investigated after experiment was scarcely affected by applied fertilizers in root zone of creeping bentgrass. The turf color index and chlorophyll index of MO, MO-Fe, MO-S treatment were higher than those of NF, and similar to those of CF. The turfgrass root in MO and MO-Fe treatment was longer than others. The dry weight of shoot in MO and MO-S was higher than CF and that of root in MO and MO-Fe, and dry weight of MO was increased than that of NF and CF, by 26% and 6%, respectively. AS compared with NF, T/R ratio of CF, MO, MO-Fe and MO-S was increased, and MO and MO-Fe was similar to CF, MO-S higher. Nutrient content in CF, MO, MO-Fe and MO-S was contained more than in NF, and it was higher in shoot. These was suggested that application of MO induced the development of quality and growth of creeping bentgrass by assisting root growth and nutrients uptake.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.147-151
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• 2016

The T91 steel (Fe-9%Cr-1%Mo) was corroded at 600 and $700^{\circ}C$ for 5 - 70 h in the $N_2$/(0.5, 2.5)%$H_2$Smixed gas at one atm. It was corroded fast, forming the outer FeS layer and the inner (FeS, $FeCr_2O_4$)-mixed layer. The formation of the outer FeS layer facilitated the oxidation of Cr to $FeCr_2O_4$ in the inner layer. Since the nonprotective FeS scale was present over the whole scale, T91 steel displayed poor corrosion resistance.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.48-54
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• 2012

The $[Fe_4S_4]^{2+}$ clusters with 2-, 3-, and 4-pyridinemethanethiolate (S2-Pic, S3-Pic, and S4-Pic, respectively) terminal ligands have been synthesized from the ligand substitution reaction of the $(^nBu_4N)_2[Fe_4S_4Cl_4]$ (I) cluster. The new $(^nBu_4N)_2[Fe_4S_4(SR)_4]$ (R = 2-Pic; II, 3-Pic; III, 4-Pic; IV) clusters were characterized by FTIR and UV-Vis spectroscopy. Cluster II was crystallized in the monoclinic space group C2/c with a = 24.530 (5) $\AA$, b = 24.636(4) $\AA$, c = 21.762(4) $\AA$, ${\beta}=103.253(3)^{\circ}$, and Z = 8. The X-ray structure of II showed two unique 2:2 site-differentiated $[Fe_4S_4]^{2+}$ clusters due to the bidentate-mode coordination by 2-pyridinemethanethiolate ligands. Cluster III was crystallized in the same monoclinic space group C2/c with a = 26.0740(18) $\AA$, b = 23.3195(16) $\AA$, c = 22.3720(15) $\AA$, ${\beta}=100.467(2)^{\circ}$, and Z = 8. The 3-pyridinemethanethiolate ligand of III was coordinated to the $[Fe_4S_4]^{2+}$ core as a terminal mode. Cluster IV with 4-pyridinemethanethiolate ligands was found to have a similar structure to the cluster III. Fully reversible $[Fe_4S_4]^{2+}/[Fe_4S_4]^+$ redox waves were observed from all three clusters by cyclic voltammetry measurement. The electrochemical potentials for the $[Fe_4S_4]^{2+}/[Fe_4S_4]^+$ transition decreased in the order of II, III and IV, and the reduction potential changes by the ligands were explained based on the structural differences among the complexes. The complex III was reacted with sulfonium salt of $[PhMeSCH_2-p-C_6H_4CN](BF_4)$ in MeCN to test possible radical-involving reaction as a functional model of the [$Fe_4S_4$]-SAM (S-adenosylmethionine) cofactor. However, the isolated reaction products of 3-pyridinemethanethiolate-p-cyanobenzylsulfide and thioanisole suggested that the reaction followed an ionic mechanism and the products formed from the terminal ligand attack to the sulfonium.