• Journal of Applied Biological Chemistry
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• v.65 no.4
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• pp.457-462
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• 2022

Manganese (Mn) exists in various oxidation states and Mn(II) is the most mobile species of Mn, which is toxic to plants and limits their growth. Therefore, the purpose of this study was to reduce Mn toxicity by immobilizing Mn using various adsorbents including iron oxides and calcium compounds. Ferrihydrite, schwertmannite, goethite were synthesized, which was confirmed by X-ray diffraction. Hematite was purchased and used as Mn adsorbent. Calcium compounds such as CaNO₃, CaSO₄, and CaCO₃ were used to increase pH and oxidize Mn. For Mn adsorption, Mn(II) solution was reacted with four iron oxides, CaNO₃, CaSO₄, and CaCO₃ for 24 hours, filtered, and the remaining Mn concentrations in the solution were analyzed by inductively coupled plasma optical emission spectroscopy. The adsorption rate and adsorption isotherm were calculated. Among iron oxides, the adsorption rate was highest for hematite followed by ferrihyrite, but goethite and schwertmannite did not adsorb Mn. In the case of calcium compounds, the adsorption rate was high in the order of CaCO₃>CaNO₃>CaSO₄. In conclusion, treatment of CaCO₃ was the most effective in reducing Mn toxicity by increasing pH.

• Resources Recycling
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• v.11 no.1
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• pp.3-8
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• 2002

In order to make the high purity Mn$_3$O$_4$powder for the raw material of soft ferrite, Mn is extracted from the dust and the extracted solution is refined. The dust is generated in producing a medium-low carbon ferromanganese and contains 90% Mn$_3$O$_4$. Mn$_3$O$_4$in the dust was reduced into MnO by roasting with charcoal. Injection of the 180g/L of the reduced dust into 4N HCI solution increased pH of the leaching solution higher than 5 and then a ferric hydroxide was precipitated. Because the ferric hydroxide co-precipitates with Si ion etc, Fe and Si ion was removed from the solution and the about 10% Mn solution was obtained. The solution was diluted with water to Mn-15000 ppm and $NH_4$F was injected into the diluted solution at $70^{\circ}C$ to the F-3000 ppm. As a result, Ca ion is precipitated as $CaF_2$and the residual concentration of Ca was 14 ppm. Injection of the equivalent (NH$1.5M_4$)$_2$$CO_3$solution as 2 L/min at $25^{\circ}C$ into the above solution precipitated a fine and high purity $MnCO_3$powder. The deposition was filtrated and roasted at $1000^{\circ}C$ for 2 hours. As a result, $MnCO_3$powder is converted into $Mn_3$$O_4$powder and it had $8.2\mu$m of median size. The final production is above 99% $Mn_3$$O_4$powder and it satisfied the requirement of high purity $Mn_3$$O_4$powder for a raw material of soft ferrite.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.82-82
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• 2008

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.3
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• pp.103-107
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• 2024

In this study, nickel, a pure metal material, was proposed as a saggar for synthesizing NCM [Li(Ni_xCo_yMn_z)O₂] cathode active material. Nickel is known as a metal that is resistant to oxidation and has a high melting point. Nickel is one of the main components of NCM cathode material and was expected to be free from problems with contamination from saggar during cathode material synthesis. We sought to confirm the possibility of nickel as a saggar for synthesizing NCM cathode active materials. When a Ni metal crucible and Ni_0.8Co_0.1Mn_0.1(OH)₂ (NCM 811) precursor material were reacted at 900℃ for a long time, the change in the reaction layer on the surface of the crucible over time was analyzed. The nickel crucible reaction layer formed during heat treatment at 900℃ was nickel oxide, and is thought to have been created by simultaneous oxygen diffusion from the cathode precursor oxide and reaction with oxygen in the atmosphere. The change in thickness of the oxide layer appears to slow down after 480 hours, which suggests that the rate of oxygen diffusion from the precursor is reduced. It remained combined without falling out of the crucible until 480 hours. However, it was confirmed that the oxide layer falls off after 720 hours, so it is thought that it can be used as saggar for NCM synthesis only for a certain period of time.

• Journal of the Korean Magnetics Society
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• v.10 no.5
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• pp.196-202
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• 2000

Top synthetic spin valves with structure Ta/NiFe/CoFe/Cu/CoFe(P1)/Ru/CoFe(P2)/FeMn/Ta on Si(100) substrate with natural oxide were prepared by dc magnetron sputtering system, and investigated on the magnetoresistance properties and effective exchange bias field. As the thickness of FeMn increased above 150 $\AA$, MR ratio was decreased due to the current shunting effect. As the thickness of free layer decreased below 40$\AA$, MR ratio was reduced rapidly. In case of 40 $\AA$ thick of free layer, spin valve film with a structure Si(100)/Ta(50 $\AA$)/NiFe(27 $\AA$)/CoFe(13 $\AA$)/Cu(26 $\AA$)/CoFe(30 $\AA$)/Ru(7 $\AA$)/CoFe(15 $\AA$)/FeMn(100 $\AA$)/Ta(50 $\AA$) exhibited maximum MR ratio of 7.5 % and an effective exchange bias field of 600 Oe, respectively. Thickness difference dependence in this synthetic spin valve structure on effective exchange field was investigated and interpreted by the analytical method. It should be noted that thickness increase of CoFe(P 1) and decrease of CoFe(P2) in synthetic antiferromagnet leaded to the decrease in effective exchange bias field by experimentally and analytically.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.225-228
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• 2000

Addition effects of metal oxide on the characteristics of infrared radiator of porous cordierite have been investigated. The porosity was increased with adding the graphite for 2MgO $.$ 2A1$_2$O$_3$$.$5SiO$_2$. The microstructure and the spectral emissivity were investigated as a function of metal oxide additives. The prosity and the emissivity were decreased with increasing amounts of CuO additives. The prosity and the emissivity were increased with increasing amounts of CoO, MnO$_2$ additives. The infrared radiator of cordierite system which spectral emissivity was 0.927 and 0.928 at from 5$\mu\textrm{m}$ to 20$\mu\textrm{m}$ wavelength as a 9wt% of CoO and MnO$_2$ additives.

• Journal of the Korean Ceramic Society
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• v.44 no.1 s.296
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• pp.52-57
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• 2007

We synthesized $(La_{1-x}Sr_x)MnO_3$ as a cathode for SOFC by glycine nitrate process (GNP) and knew the different properties of $(La_{1-x}Sr_x)MnO_3$ by using nitrate solution and oxide solution as a starting material. In case of using nitrate solution as a starting material, main crystal phase peak of $LaMnO_3$ increased as Sr content added up and a peak of $Sr_2MnO_4\;and\;La_2O_3$ was showed as a secondary phase. We added Mn excess to control a crystal phase. In this case, the electrical conductivity had a high value 210.3 S/cm at $700^{\circ}C$. On the other side, when we used oxide solution as a starting material, we found main crystal phase of $LaMnO_3$ to increase as Sr content added up and a peak of $La_2O_3$ as a secondary phase. Similary, we added Mn excess to control a crystal phase in this case. We knew $(La,Sr)MnO_3$ powder to sinter well and the electrical conductivity of the sintered body at $1200^{\circ}C$ for 4 h was 152.7 S/cm at $700^{\circ}C$. The sintered $(La,Sr)MnO_3$ powder at $1000^{\circ}C$ for 4 h got the deoxidization peak, depending on the temperature and in case of using nitrate solution as a starting material, the deoxidization peak was showed at $450^{\circ}C$ which is lower than used a oxide solution as a starting material. As a result, when $(La,Sr)MnO_3$ powder was synthesized to add Mn excess and to use nitrate solution as a starting material, we found it to have the higher deoxidization property and considered it as a cathode for SOFC properly. And we found it to have different electrical conductivity the synthesized $(La,Sr)MnO_3$ powder by using different starting materials like nitrate solution and oxide solution which influence a sintering density and crystal phase.

• Journal of the Korean Ceramic Society
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• v.44 no.11
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• pp.639-644
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• 2007

Spinel pigments, developing black color in high temperature glazes at oxidation or reduction atmosphere, without CoO because of its high price were synthesized by solid solution method. Ten mixed compositions consisted of NiO, MnO, $Fe_2O_3 and $Mn_2O_3$ were fired at $1250^{\circ}C$ for 1h. The resulting pigments were characterized by using XRD, FT-IR, SEM and UV-vis spectrometer. Structure of the pigments are spinel and particles' shape are spherical or cubic. Glazed tiles containing 5 wt% pigments were fired at $1260^{\circ}C$ and $1240^{\circ}C$ in reduction atmosphere. Color in glazes were analyzed by UV-vis spectrometer. Colors of NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole% in lime glaze showed black in oxidation, in reduction NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.55{\cdot}Mn_2O_3$ 0.0125 mole% showed black. In case of lime-barium glaze, NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.975 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black color in oxidation and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.725 MnO $0.275{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black one in reduction.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.460-464
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• 2013

A series of Mn compound were prepared by seed-assisted method. The seed used in this reaction was manufactured by calcination of $MnCO_3$ at various temperatures and effects of the calcination temperature on seed-assisted reaction were investigated. With increase of the calcination temperature, CMD (${\gamma}-MnO_2$) was recovered after seed-assisted reactions. LMO used as cathode active material in the Li-ion batteries were synthesized from Mn source obtained in the seed-assisted reaction and the electrochemical properties (rate capability, cycle life performance and specific capacity) of the LMO were investigated. The LMO synthesized from the CMD which is obtained by the reaction with seed prepared by calcination of $MnCO_3$ more than $350^{\circ}C$ shown good electrochemical properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.293-293
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• 2007

현재 활발하게 진행되고 있는 이차전지 양극 물질 중 저렴한 가격과 친환경성으로 각광받고 있는 $LiMn_2O_4$ spinel 산화물은 여러 장점에도 불구하고 용량 값이 기존 알려져 있던 Co-계 산화물에 비해 떨어지고 cycle 특성 역시 현저하게 이어진다. 이는 Mn이 전해액과의 반응에 있어 구조적인 안정성을 지니지 못하여 용출되어 나타나는 특성이다. 이번 연구에서는 Mn의 용출을 저지하고 용량의 향상을 이룰 수 있는 전이금속 중 Fe산화물을 치환하여 구조적 안정성을 갖도록 하였다. Fe산화물 치환을 통해 기본적 물성의 변화와 전기적 특성 변화를 측정하였고 공정에서의 온도 및 입도에 따른 영향도 확인하였다. Fe산화물은 Mn 자리의 3+와 4+의 자리에 치환되어 용량을 증대시키고 사이클 특성을 10회 기준으로 20%가량 향상시키는 효과를 가져왔다.