• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.223-234
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• 2019

The geology of the Samdeok Mo deposit consists of Paleozoic Hwajeonri formation, Kowoonri formation, Suchangri formation, Iwonri formation, Hwanggangri formation, Cretaceous, leucocratic porphyritic granite and granitic porphyry. This deposit consists of three quartz veins that filled NS oriented fractured zones in Suchangri formation. Quartz veins vary from 0.05 m to 0.3 m in thickness and extend to about 400 m in strike length. Quartz veins occur as massive, breccia, and cavity textures. Wallrock alteration has silicification, sericitization, argillitization and chloritization. The mineralogy of the quartz veins consists of quartz, fluorite, white mica, biotite, apatite, monazite, rutile, ilmenite, molybdenite, chalcopyrite, Fe-Mg-Mn oxide and Fe oxide. White mica from Samdeok Mo deposit occurs as fine or coarse grains in quartz vein and hostrock and has four mineral assemblages (I type: quartz, molybdenite, Fe oxide and Fe-Mg-Mn oxide, II type: quartz, Fe oxide and Fe-Mg-Mn oxide, III type: quartz and biotite, and IV type: quartz). The structural formular of white mica from quartz vein is $(K_{0.89-0.60}Na_{0.05-0.00}Ca_{0.01-0.00}Sr_{0.02-0.00})_{0.94-0.62}(Al_{1.54-1.12}Mg_{0.36-0.18}Fe_{0.26-0.09}Mn_{0.04-0.00}Ti_{0.02-0.00}Cr_{0.02-0.00}Zn_{0.01-0.00})_{1.91-1.72}(Si_{3.40-3.11}Al_{0.92-0.60})_{4.00}O_{10}(OH_{1.68-1.42}F_{0.58-0.32})_{2.00}$, but white mica of I type has higher FeO content, and lower $SiO_2$ and MgO contents than white micas of other types. Also, compositional variations in white mica from the Samdeok Mo deposit are caused by phengitic or Tschermark substitution ($(Al^{3+})^{VI}+(Al^{3+})^{IV}{\leftrightarrow}(Fe^{2+}{\text{ or }}Mg^{2+})^{VI}+(Si^{4+})^{IV}$) and direct $(Fe^{3+})^{VI}{\leftrightarrow}(Al^{3+})^{VI}$ substitution.

• Journal of Soil and Groundwater Environment
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• v.11 no.5
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• pp.35-42
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• 2006

The following results were obtained in the reductive degradation of hexachloroethane (HCA), and surface characteristics by using iron sulfide ($FeS,\;FeS_{2}$) mediators. HCA was degraded to pentachloroethane (PCA), tetrachloroethylene(PCE), trichloroethylene(TCE) and cis-l,2-dichloroethylene (cis-1,2-DCE) by complicated pathways such as hydrogenolysis, dehaloelimination and dehydrohalogenation. FeS had more rapid degradation rates of organic solvent than $FeS_{2}$. In liquidsolid reaction, the reaction rates of organic solvents were investigated to explain surface characteristics of FeS and $FeS_{2}$.. To determine surface characteristics of FeS and $FeS_{2}$, the specific surface area and surface potential of each mineral was determined and the hydrophilic site ($N_{s}$) was calculated. The specific surface area ($107.0470m^{2}/g\;and\;92.6374m^{2}/g$) and the $pH_{ZPC}$ of minerals ($FeS\;PH_{ZPC}=7.42,\;FeS_{2},\;PH_{ZPC}=7.80$) were measured. The results showed that the Ns of FeS and $FeS_{2}$ were $0.053\;site/mm^{2}\;and\;0.205\;site/mm^{2}$, respectively. $FeS_{2}$ had more hydrophilic surface than FeS. In other words, FeS have more hydrophobic surface site than $FeS_{2}$.

• Journal of Electrochemical Science and Technology
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• v.4 no.3
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• pp.102-107
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• 2013

The electrochemical properties of Mg-doped $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ and pure $LiFe_{0.5}Mn_{0.5}PO_4$ olivine cathodes are examined and the lattice parameters are refined by Rietveld analysis. The calculated atomic parameters from the refinement show that $Mg^{2+}$ doping has a significant effect in the olivine $LiFeMnPO_4$ structure. The unit cell volume is 297.053(2) ${\AA}^3$ for pure $LiFe_{0.5}Mn_{0.5}PO_4$ and is decreased to 296.177(1) ${\AA}^3$ for Mg-doped $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ sample. The doping of $Mg^{2+}$ cation with atomic radius smaller than $Mn^{2+}$ and $Fe^{2+}$ ion induces longer Li-O bond length in $LiO_6$ octahedra of the olivine structure. The larger interstitial sites in $LiO_6$ octahedra facilitate the lithium ion migration and also enhance the diffusion kinetics of olivine cathode material. The $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ sample with larger Li-O bond length delivers higher discharge capacities and also notably increases the rate capability of the electrode.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.170-171
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• 2012

$Fe_2O_3$, Al, Cr과 Si 분말을 고 에너지 볼 밀링해서 나노분말을 제조한 후 고주파유도 가열 활성 연소합성 장치로 1분 이내의 짧은 시간에 합성 및 소결한 $Al_2O_3+4.65(Fe_{0.43}Cr_{0.17}Al_{0.323}Si_{0.077})$, $Al_2O_3$ + 5.33 ($Fe_{0.375}Cr_{0.11}Al_{0.3}Si_{0.075}$), $Al_2O_3$ + 6.15 ($Fe_{0.325}Cr_{0.155}Al_{0.448}Si_{0.072}$), $Al_2O_3$ + 3.3 ($Fe_{0.6}Cr_{0.3}Al_{0.6}$) 소결체 시편을 $700^{\circ}C$의 온도에서 100시간 동안 공기 중에서 산화 및 $N_2-H_20-H_2S$ 혼합 가스 내에서 황화 부식을 실시하였다. 그 결과 산화 및 황화 부식 후에 ${\alpha}-Al_2O_3$가 표면에 생성되어 보호 피막으로 작용하여 우수한 내식성을 보였다.

• Applied Biological Chemistry
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• v.21 no.1
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• pp.40-50
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• 1978

Effects of Zn, P and Fe on Cd uptake and accumulations by tomato (Lycopersicum esculentum Mill) and also their interactions on the uptake of Zn, Fe, Mn, P and Cd were investigated using batch type solution culture technique. Experiment 1 was a factorial scheme with 3 levels of Zn (0, 0.5, 2.5 ppm) and 3 levels of Cd (0, 0.2, 1.0 ppm). At 1.0 ppm Cd, significant yield reduction of dry matter and visual toxicity symptoms (yellowing and necrosis) of Cd was observed for all zinc levels. At this Cd level, increasing Zn treatment from 0 to 2.5 ppm increased Cd concentration from 199 to 235 ppm in leaves and from 124 to 145 ppm in stems. Similarly, Cd treatment did not suppress Zn uptake in leaves, and rather significantly increased in stems. Fe concentrations in leaves and stems were significantly reduced due to Cd treatment while Mn were increased by both Zn and Cd treatment. The results of experiment 2 with 3 levels of P (0.5, 2.0, 4.0m Mol) and 3 levels of Cd (0, 1.0, 2.0 ppm) in a factorial scheme also showed a growth reduction and visual toxic symptons from 1.0 ppm Cd level. Increasing P treatment tend to increase Cd concentrations in leaves and stems although it was not statistically significant. Increasing P concentration due to Cd treatment could be the 'concentration' effect as a result of reduced growth, while there was significant decrease in Fe concentration due to Cd treatment in spite of possible 'concentration' effect. Mn concentration was increased at 1.0 ppm Cd level and then dropped at 2.0 ppm Cd level. Zu concentration in leaves and stems showed significant increase as Cd treatment increased as observed in experiment 1. Experiment 3 had 3 levels of Fe (0.5, 1.0, 2.0 ppm) and 3 levels of Cd (0, 0.8, 1.6 ppm) treatments in a factorial design. Significant growth reduction and visual toxic symptoms as observed in experiment 1 and 2 were also observed from 0.8 ppm Cd level. Increasing Fe treatment obviously alleviated toxic symptoms, improved growth and significantly increased dry matter yield. At 0.8 ppm Cd treatment level, increasing Fe treatment from 0.5 to 2.0 ppm significantly decreased Cd concentration from 141 to 92 ppm in leaves and from 101 to 46 ppm in stems. At 1.6 ppm Cd treatment level the decrease was from 224 to 167 ppm in leaves and from 124 to 109 ppm in stems. As in the case of experiment 1 and 2, Fe concentration in leaves and stems were reduced as Cd treatment increased to 1.6 ppm at 0.5 and 1. 0 Fe treatment levels, whereas at 2.0 ppm Fe level, Cd treatment increased Fe concentration in leaves and stems showing significant interactions of Fe and Cd on Fe uptake. Cd effect on Zn and Mn showed similar results to experiment 1 and 2 and Fe treatments reduced Zn and Mn concentrations in plant tissue. The results of 3 experiments show that P and Zn did not manifest suppressive effect on Cd uptake, Fe significantly demonstrated it. Fe also alleviated Cd toxicity symptoms significantly in terms of visual symptoms and dry matter yield. Visual toxicity symptoms were definitely related to Fe status in plant tissue as well as possible physiological effect of Cd itself, and the results suggest that Fe requirement for normal growth increase as Cd element is present in plant tissue. Zn accumulated more in stems than in leaves whereas Cd, Fe and Mn showed the opposite trend in all experiments.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.912-918
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• 2002

Ni-Mn-Co-Fe oxide thick films were coated on an alumina substrate by screening printing technique. The microstructure and electrical properties of the thick films, as a function of composition and sintering temperature, were investigated. The components of the NTC thick films sintered at 1150${\circ}C$ were distributed homogeneously. On the other hand, in the case of the NTC thick films sintered at 1200 and 1250${\circ}C$, Co element was distributed homogeneously, but Ni, Mn and Fe elements were distributed heterogeneously, resulting in the formation of Ni rich and Mn-Fe rich regions. All the thick film NTC thermistors prepared showed a linear relationship between log resistance (log R) and the reciprocal of absolute temperature (1/T), indicative of NTC characteristics. At a given NiO and $Mn_3O_4$ content, the resistance, B constant and activation energy of $(Ni_{1.0}Mn_{1.0}Co_{1-x}Fe_x)O_4$ (0.25${\le}$x${\le}$0.75) and $(Ni_{0.75}Mn_{1.25}Co_{1-x}Fe_x)O_4$ (0.25${\le}$x${\le}$0.75) thermistors increased with increasing $Fe_2O_3$ content.

• Journal of the Korean Chemical Society
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• v.37 no.11
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• pp.923-928
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• 1993

The series of solid solutions in the $Sr_{1+x}Ho_{1-x}FeO_{4-y}$ (x = 0.00, 0.25, 0.50, 0.75 and 1.00) systems with $K_2NiF_4$ type structure have been prepared at 1550$^{\circ}$C under an atmospheric air pressure. The X-ray powder diffraction spectra of these samples assign that the crystallographic phases are tetragonal system over the whole x range. The lattice volume was increased with increasing the substitution amount of the $Sr^{2+}$ ion. The mole ratio of the $Fe^{4+}$ ion to total iron ions or ${\tau}$ value has been determined by Mohr salt titration of the sample and then the y value was calculated from x and ${\tau}$ values. The ${\tau}$ and y values have been increased with x values. The nonstoichiometric chemical formula are formulated from the general formula of $Sr_{1+x}Ho_{1-x}Fe^3_{1-}\;^+_{\tau}Fe_{\tau}^{4+}O_{4-y}$ replaced by x,${\tau}$ and y values. Mossbauer spectra show the mixed valence state and coordination state of $Fe^{3+}\;and\;Fe^{4+}$ ions. It is found out that the magnetic property of the samples is paramagnetic at room temperature. Electrical conductivity varied within the semiconductivity range of 1.0 to 1 ${\times}\;10^{-9}{\Omega}^{-1}cm^{-1}$. Activation energy of the electrical conductivity was decreased with the $\tau$ value. The conduction mechanism should be explained by the hopping model of the conduction electrons between the valence states of $Fe^{3+}\;and\;Fe^{4+}$ ions.

• Journal of the Korean Ceramic Society
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• v.29 no.12
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• pp.942-948
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• 1992

Ultrafine iron oxide powder, {{{{ gamma }}-Fe2O3 and $\alpha$-Fe2O3, were prepared by the thermal decomposition of organometallic compounds. The formation process of powder includes the thermal decomposition and oxidation of the organometallic precursors, Fe(N2H3COO)2(N2H4)2 (A) and N2H5Fe(N2H3COO)3.H2O (B). The organometallic precursors, A and B, were synthesized by the reaction of ferrous ion with hydrazinocarboxylic acid, and characterized by quantitative analysis and infrared spectroscopy. The mechanistic study for the thermal decomposition was performed by DAT-TG. The iron oxide powder was obtained by the heat treatment of the precursors at 20$0^{\circ}C$ and $600^{\circ}C$ for half an hour in air. The phases of the resulting product were proved {{{{ gamma }}-Fe2O3 and $\alpha$-Fe2O3 respectively. The particle shape was equiaxial and the particle size was less than 0.1 ${\mu}{\textrm}{m}$. Magnetic properties of the {{{{ gamma }}-Fe2O3 powder obtained from A and B was 234 Oe of coercivity, 64.26 emu/g of saturation magnetization, 23.59 emu/g of remanent magnetization and 24.1 Oe, 47.27 emu/g, 3.118 emu/g respectively. The value of $\alpha$-Fe2O3 powder was 1.494 Oe, 0.4862 emu/g, 0.1832 emu/g and 1,276 Oe, 0.4854 emu/g, 0.1856 emu/g respectively.

• Journal of Electrochemical Science and Technology
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• v.10 no.3
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• pp.321-328
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• 2019

A new miniaturized all solid-state contact Fe (III)-selective PVC membrane electrode based on Fe (II) phthalocyanine as a neutral carrier was described. The effects of the membrane composition and foreign ions on the electrode performance was investigated. The best performance was obtained with a membrane containing 32% poly (vinyl chloride), 64% dioctylsebacate, 3% Fe (II) phthalocyanine, and 1% potassium tetrakis (p-chlorophenyl) borate. The electrode showed near Nernstian response of $26.04{\pm}0.95mV/decade$ over the wide linear concentration range $1.0{\times}10^{-6}$ to $1.0{\times}10^{-1}M$, and a very low limit of detection $1.8{\pm}0.5{\times}10^{-7}M$. The potentiometric response of the developed electrode was independent at pH 3.5-5.7. The lifetime of the electrode was approximately 3 months and the response time was very short (< 7 s). It exhibited excellent selectivity towards Fe (III) over various cations. The miniaturized all solid-state contact Fe (III)-selective membrane electrode was successfully applied as an indicator electrode for the potentiometric titration of $1.0{\times}10^{-3}M$ Fe (III) ions with a $1.0{\times}10^{-2}M$ EDTA and the direct determination of Fe (III) ions in real water samples.

• Journal of Korea Foundry Society
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• v.24 no.6
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• pp.356-365
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• 2004

Mechanical properties and microstructures of the Ni-AI-Fe and Ni-AI-Fe-(B, Zr) alloys which containing $10{\sim}30at$.%Fe, 0.1at.%B and/or 0.1at.%Zr have been investigated. The experimental results showed that the microstructures of Ni25Al were changed from a single phase ${\gamma}$ to dual phase ${\gamma}$ and ${\beta}$ by addition of 27at.%Fe. Ni45Al, however, kept the single ${\beta}$ phase even though Fe was added upto 30at.%. The hardness of Ni25Al were increased from $H_RB$ 70 to $H_RC$ 39 by addition of 27at.%Fe. In the case of Ni45Al which have $H_RC$ 37, the hardness was decreased by lOat.%Fe addition, but increased with 30at.%Fe. The yield strength and ultimate compressive strength in the compressive test have showed a similar trend with the hardness change. The strain to fracture was 14% at maximum and achieved in Ni25Al-27at.%Fe and Ni25Al-27at.%Fe-0.1 at.%B alloys. The Ni45Al showed a relatively low strain to fracture as 4%. The impact absorption energy of Ni25Al increased from 0.74 kg-m to 1.81 kg-m by addition of 27at.%Fe. In case of Ni45Al, the addition of lOat.%Fe and lOat.%Fe with small amounts of Band Zr did not change significantly the impact absorption energy of 0.60 kg-m, whereas the addition of 30at.%Fe with small amounts of B and Zr increased it slightly. In fracture tests, both of two basic materials showed the same intergranular fracture but by adding Fe it changed to the cleavage fracture mode or co-existing of cleavage and intergranular fractures.