• Title, Summary, Keyword: MnO$_2$

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Synthesis of Cobalt Oxide Free Black Color Spinel Pigment (CoO가 첨가되지 않은 스피넬계 흑색안료의 합성)

  • Kim, Jun-Ho;Lee, Seong-Ho;Suh, Man-Chul;Lee, Byung-Ha
    • 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.

Phase Change of Nanorod-Clustered $MnO_2$ by Hydrothermal Reaction Conditions and the Lithium-ion Battery Cathode Properties of $LiMn_2O_4$ Prepared from the $MnO_2$ (수열합성 조건에 따른 나노로드 클러스터형 $MnO_2$의 상변화와 이를 이용한 $LiMn_2O_4$의 리튬이온전지 양전극 특성)

  • Kang, Kun-Young;Choi, Min Gyu;Lee, Young-Gi;Kim, Kwang Man
    • Korean Chemical Engineering Research
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    • v.49 no.5
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    • pp.541-547
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    • 2011
  • Nanorod-clustered $MnO_2$ precursors with ${\alpha}$-, ${\beta}$-, and ${\gamma}$-phases are synthesized by hydrothermal reaction of $MnSO_45H_2O$ and $(NH_4)S_2O_8$. The formation of nanorod-clustered ${\beta}-MnO_2$ is particularly confirmed under the conditions of high reactant concentration and hydrothermal reaction at $150^{\circ}C$. The spinel $LiMn_2O_4$ nanorod-clusters are also prepared by lithiating the $MnO_2$ precursors, varying the concentration of lithiating agent ($LiC_3H_3O_2{\cdot}2H_2O$) and heat treatment temperature, and characterized for use as cathode material of lithium-ion batteries. As a result, the nanorod-clustered $LiMn_2O_4$ prepared from the ${\beta}-MnO_2$ at higher $LiC_3H_3O_2{\cdot}2H_2O$ concentration and the annealing at $800^{\circ}C$ is proven to show the cubic spinel structure and to achieve the high initial discharge capacity of 120 mAh/g.

Element Dispersion by the Wallrock Alteration of Janggun Lead-Zinc-Silver Deposit (장군 연-아연-은 광상의 모암변질에 따른 원소분산)

  • Yoo, Bong Chul
    • Economic and Environmental Geology
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    • v.45 no.6
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    • pp.623-641
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    • 2012
  • The Janggun lead-zinc-silver deposit is hydrothermal-metasomatic deposit. We have sampled wallrock, hydrother-maly-altered rock and lead-zinc-silver ore vein to study the element dispersion during wallrock alteration. The hydrothermal alteration that is remarkably recognized at this deposit consists of rhodochrositization and dolomitization. Wallrock is dolomite and limestone that consisit of calcite, dolomite, quartz, phlogopite and biotite. Rhodochrosite zone occurs near lead-zinc-silver ore vein and include mainly rhodochrosite with amounts of calcite, dolomite, kutnahorite, arsenopyrite, pyrite, chalcopyrite, sphalerite, galena and stannite. Dolomite zone occurs far from lead-zinc-silver ore vein and is composed of mainly dolomite and minor calcite, rhodochrosite, pyrite, sphalerite, chalcopyrite, galena and stannite. The correlation coefficients among major, trace and rare earth elements during wallrock alteration show high positive correlations(dolomite and limestone = $Fe_2O_3(T)$/MnO, Ga/MnO and Rb/MnO), high negative correlations(dolomite = MgO/MnO, CaO/MnO, $CO_2$/MnO, Sr/MnO; limestone = CaO/MnO, Sr/MnO). Remarkable gain elements during wallrock alteration are $Fe_2O_3(T)$, MnO, As, Au, Cd, Cu, Ga, Pb, Rb, Sb, Sc, Sn and Zn. Remarkable loss elements are CaO, $CO_2$, MgO and Sr. Therefore, elements(CaO, $CO_2$, $Fe_2O_3(T)$, MgO, MnO, Ga, Pb, Rb, Sb, Sn, Sr and Zn) represent a potential tools for exploration in hydrothermal-metasomatic lead-zinc-silver deposits.

Effect of Luminescence with Coactivator of $ZnGa_2O_4$:Mn,X phosphor ($ZnGa_2O_4$:Mn,X 형광체의 부활성제에 따른 발광 효과)

  • 박용규;한정인;주성후
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.3
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    • pp.242-247
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    • 1998
  • In this study, we have synthesized $ZnGa_2O_4$:Mn,X powder doped with Mn, MnO, $MnF_2$ and $MnCl_2$, low voltage green emitting phosphor, in vacuum atmosphere. From PL spectra, the intensity of the emission peak, the brightness with coactivator show that $ZnGa_2O_4$:Mn,Cl > $ZnGa_2O_4$:Mn,F > $ZnGa_2O_4$:Mn,O > $ZnGa_2O_4$:Mn. These improvement of the brightness are caused by the increase of the concentration of $Mn^{2+}$ ion. In case of $ZnGa_2O_4$:Mn,Cl and ZnGa$_2$O$_4$:Mn,F, the brightness is enhanced much more, which is owed to the decrease of defect of host material. For $ZnGa_2O_4$:Mn,Cl phosphor fabricated with optimized condition, the decay time becomes short from 30 ms of the $ZnGa_2O_4$:Mn and $ZnGa_2O_4$:Mn,O to 6 ms and the brightness of CL at 1 kV, 1 mA is 60 cd/$m^2$.

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The Synthesis and Electrochemical Properties of Lithium Manganese Oxide (Li2MnO3)

  • Seo, Hyo-Ree;Lee, Eun-Ah;Yi, Cheol-Woo;Kim, Ke-On
    • Journal of Electrochemical Science and Technology
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    • v.2 no.3
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    • pp.180-185
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    • 2011
  • The layered lithium-manganese oxide ($Li_2MnO_3$) as a cathode material of lithium ion secondary batteries was prepared and characterized the physico-chemical and electrochemical properties. The morphological and structural changes of MnO(OH) and $Li_2MnO_3$ are closely connected to the changes of electrochemical properties. The crystallinity of $Li_2MnO_3$ is enhanced as the annealing temperature increase, but its capacity is reduced due to the easier structural changes of less crystalline $Li_2MnO_3$ than highly crystalline one. Moreover, the addition of buffer material such as MnO(OH) into cathode causes to reduce the morphological and structural changes of layered $Li_2MnO_3$ and increase the discharge capacity and cycleability.

Fabrication of Core/Shell Structured SiO2/Zn2SiO4:Mn2+ Composite and Its Photoluminescence Properties

  • Park, Jehong;Kim, Jongsu;Kwon, Hansang
    • Journal of the Korean Physical Society
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    • v.71 no.7
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    • pp.370-373
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    • 2017
  • Core/shell structured $SiO_2/Zn_2SiO_4:Mn^{2+}$ composite was prepared by thermal-diffusion reaction between $SiO_2$ and $Zn_{1-x}Mn_xO$ particles, which is a low cost solid-state method. The X-ray diffraction and scanning electron microscope results showed that a $5-{\mu}m$-thick dense $Zn_2SiO_4:Mn^{2+}$ layer was successfully formed on the surface of the $SiO_2$ particles. The PL spectrum of the $SiO_2/Zn_2SiO_4:Mn^{2+}$ composite revealed a green emission peak at 526 nm with PL intensity 20% higher than that of the conventional $Zn_2SiO_4:Mn^{2+}$ particles. In addition, the decay time of the $SiO_2/Zn_2SiO_4:Mn^{2+}$ composite was shorter (${\tau}_{10%}=7ms$) than that of the conventional $Zn_2SiO_4:Mn^{2+}$ particles (${\tau}_{10%}=12ms$), which is owing to the relaxation of forbidden transition of $Mn^{2+}$ ions due to the localized stress of $Mn^{2+}$ ions arising from the surface tension in the $SiO_2/Zn_2SiO_4:Mn^{2+}$ composite.

Hydrothermal synthesis of $(Li,Al)MnO_2(OH)_2$:Co compound (수열법에 의한 $(Li,Al)MnO_{2}(OH)_{2}$:Co 화합물의 합성)

  • 최종건;황완인;김판채
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.11 no.4
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    • pp.154-159
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    • 2001
  • (Li,Al)$MnO_2(OH)_2$:Co compound was synthesized by hydrothermal method. $MnO_2$, LiOH.$H_2$O, $Co_3O_4$ and $Al(OH)_3$ were used as starting materials and the optimum conditions for synthesis of monolithic (Li,Al)$MnO_2(OH)_2$:Co compound were as follows : reaction temperature; $200^{\circ}C$, reaction time; 3 days, hydrothermal solvent; 3M-KOH solution, reaction apparatus; seesaw type, atomic ratio of Li:Al:Mn;Co = 1:2.1:2.5~2:0.5~1. Monolithic(Li,Al)$MnO_2(HO)_2$:Co compound synthesized in this work had a god crystallinity and excellent color forming effect as a blue pigment compatible with natural mineral. The particles of the synthesized (Li,Al)$MnO_2(OH)_2$:Co compound have hexagonal plate shape with the size of 0.5~1 $\mu\textrm{m}$.

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Effect of MnO2 Addition on Electrical Properties and Microstructure in Pb[Cd1/2W1/2)0.02Zr0.505Ti0.475]O3 (Pb[Cd1/2W1/2)0.02Zr0.505Ti0.475]O3조성에서의 MnO2첨가에 대한 영향)

  • 김대웅;김병익;김호기
    • Journal of the Korean Ceramic Society
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    • v.25 no.6
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    • pp.571-576
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    • 1988
  • The microstructure and electrical properties of 0.02Pb[Cd1/2W1/2)O3-0.505PbZrO3-0.475PbTiO3 with MnO2 addition have been investigated. The amount of MnO2 addition was 0, 0.2, 0.4, 0.6, 0.8, 1wt%, respectively. When MnO2 is added up to 0.2wt%, Mn3+ which is substituted for Ti4+ site make hole and act as a acceptor. When MnO2 is added over 0.2wt% Mn3+ which is substituted for Cd2+ site create electron and act as a donor. The variation of grain size show that it was rapidly increased by 0.4wt% addition of MnO2, and while that in the range of over 0.6wt% addition of MnO2 it was decreased. The solid solution range of MnO2 that assumed in this composition according to the variations of microstructure and electrical properties was 0.4-0.6wt%.

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Effect of MnO2 Addition on Sintering and PTCR Properties in Y2O3 doped BaTiO3 Semiconducting Ceramics (MnO2첨가가 Y2O3 doped BaTiO3 반도체 세라믹스의 소결 및 PTCR특성에 미치는 영향)

  • 이준형;박금덕;김정주;조상희
    • Journal of the Korean Ceramic Society
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    • v.27 no.1
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    • pp.7-12
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    • 1990
  • The influence of MnO2 on the sintering property and PTCR behavior of(Ba0.8Sr0.2)TiO2 has been investigated. And the densities, grain sizes and electrical resitivities of specimens were measured as a function of doping with Mn ion of varying concentration. The density and grain size of the sintered specimens were almost the same regardless of MnO2 addition up to 0.2mol% MnO2. But in the case of 0.25mol% MnO2 addition, abnormal grain growth was appeared. So the grain size distribution was wide and density decreased greatly. The room-temperature resistivity increased as Mn content increased and the temperature coefficient of resistivity was highest in the case of 0.15mol% MnO2 addition.

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Stabilization of LiMn2O4 Electrode for Lithium Secondary Battery(I) - Electrode Characteristics on the Substitution of Metal Oxides in LiMn2O4 Cathode Material - (리튬이차전지용 정극활물질 LiMn2O4의 안정화(I) - LiMn2O4에 대한 금속산화물의 치환에 따른 전극 특성 -)

  • Lee, Jin-Sik;Lee, Chul-Tae
    • Applied Chemistry for Engineering
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    • v.9 no.5
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    • pp.774-780
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    • 1998
  • For the stabilization of the spinel structured $LiMn_2O_4$, a fraction of manganese was substituted with various metals such as Mg, Fe, V, W, Cr, Mo with Mn that had a similar ionic radii ($LiM_xMn_{2-x}O_4(0.05{\leq}x{\leq}0.02)$). The $LiM_xMn_{2-x}O_4$ showed a substantial improvement as lower capacity loss than that of the spinel structured $LiMn_2O_4$ when it was used as a cathode material. And with the partial substitution, the chemical diffusion coefficient for $LiMg_{0.05}Mn_{1.9}O_4$ and $LiCr_{0.1}Mn_{1.9}O_4$ was increased by and order of magnitude compared to that of the $LiMn_2O_4$ with spinel structure. The results showed that significant improvement can be made on the electrochemical characteristics as the structure of the $LiMn_2O_4$ electrode material was stabilized by the partial substitution.

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