• Journal of the Korean Chemical Society
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• v.39 no.6
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• pp.446-452
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• 1995

Lithium intercalates, $Li_xFeMoO_4Cl$ ($1{\leq}X{\leq}2$) prepared by electrochemical lithiation of $FeMoO_4Cl$ crystallizes in monoclinic structure for all x values as revealed by x-ray diffraction and galvanostatic discharge experiments. According to the x-ray photoelectron spectroscopic study, Fe(III) is at first reduced to Fe(II) upon lithium intercalation with the x domain of $0{\leq}X{\leq}1$, where the crystal symmetry is changed from tetragonal to monoclinic. On the other hand, Mo(VI) is reduced to lower valent state upon further lithium intercalation ($1{\leq}X{\leq}2$), where no crystal symmetry transformation and reduction of Fe(II) to lower valent state are observed. The Mo 3d spectrum for $Li_2FeMoO_4Cl$ appears as a complex shape, but can be deconvoluted into the three sets of the doublet on the basis of Gaussian function, those which correspond to Mo(VI), Mo(V) and Mo(IV) states, respectively. The mixed valent states of molybdenum after further lithiation may be due to a competitive reaction between the formation of Mo(V) and its disproportionation to Mo(IV) and Mo(VI).

• Journal of the Korean Magnetics Society
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• v.24 no.3
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• pp.71-75
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• 2014

Ground state energy levels of the $Fe^{3+}$ paramagnetic impurity ion in stoichiometric $LiTaO_3$ and in congruent $LiTaO_3$ single crystals were calculated with electron paramagnetic resonance constants. Energy levels between six energy levels were obtained with spectroscopic splitting parameter g and zero field splitting constant D for $Fe^{3+}$ ion. The energy diagrams of $Fe^{3+}$ ion were different from different magnetic field directions ([100], [001], [111]) when magnetic field increases. The calculated ZFS energies of $Fe^{3+}$ ion in stoichiometric and congruent $LiTaO_3$ single crystals for ${\mid}{\pm}5/2$ > ${\leftrightarrow}{\mid}{\pm}3/2$ > and ${\mid}{\pm}3/2$ > ${\leftrightarrow}{\mid}{\pm}1/2$ > transitions were 12.300 GHz and 6.150 GHz, and 59.358 GHz and 29.679 GHz, respectively. It turns out that energy levels of $Fe^{3+}$ paramagnetic impurity in $LiTaO_3$ crystal are different from different crystal growing condition.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.31-44
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• 2012

Seasonal changes in groundwater geochemistry exist in Ddan-sum island. In the farming season of April, the spatial distribution of ions explains that $Fe^{2+}$, Fe(total), $Mn^{2+}$, $Ca^{2+}$, $Mg^{2+}$, $SiO_2$, ${HCO_3}^-$, and ${NO_3}^-$ are high in the center of the island, but $Na^+$ and $K^+$ are relatively low and these high anions indicates the effect of fertilizer used for strawberry cultivation. Spatial variation of ion concentration is smaller in August than April because of low agricultural activity and heavy rainfall. Geochemical type of groundwater shows that the center of island has the characteristics of recharge zone but the rim area corresponds to a mixing zone between groundwater and stream water. According to the analysis of saturation index for Fe and Mn ions, hematite, goethite, and rhodochrosite under supersaturation have a possibility of additional mineral deposition, and siderite, $Fe(OH)_3$, manganite, pyrolusite, and pyrochroite under unsaturation may exist as a type of dissolved ion.

• Journal of the Korean Magnetics Society
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• v.19 no.3
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• pp.106-112
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• 2009

$Ni_{1-x}Mg_xFe_2O_4$ ferrite system was studied by using X-ray diffraction and $M{\ddot{o}}ssbauer$ spectroscopy. The samples were prepared by ceramic sintering method with Mg content x. The X-ray diffraction patterns of samples show phase of cubic spinel structure. There are no remarkable changes of lattice constants in $Ni_{1-x}Mg_xFe_2O_4$ ferrite system. The $M{\ddot{o}}ssbauer$ spectra were consisted of two sets of six lines, respectively, corresponding to $Fe^{3+}$ at tetrahedral and octahedral sites. The magnetic hyperfine field of samples was decreased as increasing Mg contents x in both sites and it was shown Yafet-Kittel magnetic structure. $NiFe_2O_4$ was shown complete inverse spinel, but $NiFe_2O_4$ was shown partial inverse spinel which absorption area ratio (oct/tet) was 1.449 in $M{\ddot{o}}ssbauer$ spectrum.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.285-297
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• 2002

This study was carried out to prove the factor properties of the soil affected by a forest fire through the physical and chemical analysis and the data from the conclusion of those analysis are applied to the development of technics that reduces a forest fire-induced 2nd damage. The forest fire was in December 2000 at Gangreung city and Donghae city, Gangwon provinces, Korea. Soil samples were collected at upper layers (0-5 cm) and bottom layers (5-40 cm) in November 2001 from the burned and control sites. Values of pH in burned soils of the upper layers affected by forest fire are higher than those in control soils. Both the fragments of fire-burned plant and differences of geological properties are resulted in a class of soil. Contents of organic matters in burned soils are higher than those in control soils, exceptionally the contents of organic matters in burned soils that contain coaly shale are lower than those in control soils. Weathering indices in burned soils are higher than those in control soils and it concerned with loss of soil. Iron ions Fe(Fe$^{2+}$ or Fe$^{3+}$) are easily extracted from the burned soils by rainfall, but Mn ions are straightly exist in the burned soils by physiochemical adsorption of colloid. Through the sequential extraction in the burned soils and control soils, we are certificate the extraction of Fe ions and the disturbance of Mn ions from the burned soils. As a consequence of factor analysis in burned soil and control soil, we are certificate that the influence of forest fire results in a disturbance of positive correlation factors.

• Journal of the Korean Chemical Society
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• v.31 no.1
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• pp.45-54
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• 1987

Dowex 1-X8 resin ion exchanged with calcon carboxylic acid (CCA-Dowex 1-X8) and 2-methyl-8-hydroxyquinoline(MHQ) impregnated-Amberlite XAD-4 resin (MHQ-XAD-4) were examined for the separation and preconcentration of ferric ion from the various matrices. The stabilities of these resins were investigated, and their capacities on ferric ion were also measured. The effect of pH on the adsorption of ferric ion and matrix ions, such as Al(Ⅲ) and Ca(Ⅱ), was investigated to determine the optimun pH ranges. Separation and preconcentration of iron in aluminium foil and mineral water samples were studied by elution method with these resin columns. The recovered ions by 10ml of 2F nitric acid was determined by flame atomic spectrophotometry. SP-Sephadex C-25 column was used to separate ferrous and ferric ion in mineral water by stepwise elution with ferrozine and 1 % ascorbic acid-ferrozine solution. The concentrated and separated each ion could be determined spectrophotometrically at the analytical wavelenth of Fe(Ⅱ)-ferrozine complex (562nm).

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.593-597
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• 2015

Tricyclopentadiene (TCPD) as a next generation high density fuel was synthesized by Diels-Alder oligomerization reaction of DCPD. TCPD was prepared by ionic liquid (IL) catalysts with combination of cationic and anionic precursors. Two kinds of anionic precursors such as copper(I) chloride (CuCl) and iron(III) chloride ($FeCl_3$) and cationic precursors such as triethylamine hydrochloride (TEAC) and 1-butyl-3-methylimidazolium chloride (BMIC) were used. The preparation of TCPD using IL catalyst was superior to that using Diels-Alder reaction in terms of DCPD conversion and TCPD yield. In addition, TCPD yield was correlated with Lewis acidity by changing the ratio of anionic and cationic precursors. The TCPD yield was higher when using CuCl as anionic precursor than that of using $FeCl_3$. Control of Lewis acidity by changing the molar ratio of anionic and cationic precursors could further improve TCPD yield as well.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.337-342
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• 1997

We have investigated Mossbauer effect and emission properties of the Fe-doped GaAs grown by liquid phase epitaxy (LPE). The powder type of isotope $^{57}Fe$ was used as a dopant source in LPE-GaAs. From the analysis of Mossbauer effect the value of isomer shift, 0.303$\pm$0.018 mm/sec, is calculated at low temperature. This means that charge state of Fe ion in GaAs is 3+. The results of double crystal x-ray rocking curve (DCRC) and low temperature photoluminescence (PL) show the crystal quality of the epitaxial layers are good. Unusual luminescence peaks from the Fe-GaAs epitaxial layers appeared at emission energy of 0.99 eV and 1.15 eV. We attribute these emissions to Fe-acceptor related two deep radiative centers.

• Resources Recycling
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• v.2 no.2
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• pp.1-8
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• 1993

This study was carried out in order to define the effective collectors and the opitimum conditions for the removal of iron ion in waste water by flotation method. The results obtained in this study are summarized as follows. Fe(II) and Fe(III) were removed effectively at pH7 and 6 respectively by using sodium lauryl sulfate, an anionic collector. The anionic collector, aeropromotor 845, removed both Fe(II) and Fe(III) effectively in pH ranges of from 5 to 9. The cationic collector, trimetyl dodecyl ammonium chloride, removed both Fe(II) and Fe(III) effectively in pH ranges from 10 to 11 and from 4 to 10, respectively. Therefore, Fe(II) and Fe(III) could be effectively removed by forming the iron hydroxide precipitates by simple pH adjustment of the solutions above precipitation point of ferrous and ferric ion by flotation method. Then, the effective pH regulator and collector were NaOH and $Na_2CO_3$,aeropromotor 845 and trimetyl dodecyl ammonium chloride, respectively.

• Journal of the Korean Magnetics Society
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• v.21 no.6
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• pp.198-203
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• 2011

The electronic structure of ferrimagnetic spinel oxide of $FeV_2O_4$ has been investigated by employing soft x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD). The Fe 2p and V 2p XAS spectra show that the valence states of Fe and V ions are ${\sim}Fe^{2.3+}$ mixed-valent states and ${\sim}V^{3+}$ states, respectively. In Fe 2p XMCD spectra, finite XMCD signals are observed for divalent $Fe^{2+}$ states only, but not for $Fe^{3+}$ states. This finding indicates that the magnetic moments of $Fe^{2+}$ ions are ordered ferromagnetically but that those of $Fe^{3+}$ ions are cancelled, implying that $Fe^{2+}$ ions play an important role in determining magnetic properties of $FeV_2O_4$.