• Journal of Powder Materials
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• v.8 no.3
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• pp.201-206
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• 2001

$>LaMnO_3$$(La, Sr)MO_3$, and $(La, Sr)MO_3/YSZ$ gel films were deposited by spin-coating technique on scandium-doped zirconia (YSZ) substrate using the precursor solution prepared from $La(O-i-C_3H_7)_3$, $Co(CH_3COO)_2$or $Mn(O-i-C_3H_7)_2$,2-methoxyethanol, and polyethylene glycol. By heat-treating the gel films, the electrochemical cells, $(La, Sr)MnO_3{\mid}ScSZ{\mid}Pt$ were fabricated. The effect of polyethylene glycol on the microstructure evolution of $$LaCoO_3and $LaMnO_3$thin films was investigated, and NOx decomposition characteristics of the electrochemical cells were investigated at $500^{\circ}C$ to $600^{\circ}C$. By applying a direct current to the $(La, Sr)MnO_3{\mid}ScSZ{\mid}Pt$ electrochemical cell, good NOx conversion rate could be obtained relatively at low current value even if excess oxygen is included in the reaction gas mixture.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.386-387
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• 2005

anodic deposition법으로 제조된 $MnO_2$와 (Mn, Zn) 산화물의 전도도를 측정하였다. 제조된 Mn 산화물의 조성은 XRD와 EDS를 이용하여 $MnO_2$ 와 Mn 복합산화물로 확인되었다. DV-Xa법으로 계산된 이론 전자상태 계산 결과 천이금속을 첨가하게 되면, Mn 복합 산화물의 에너지 갭이 감소하는 것으로 나타났다. anodic deposition법으로 제조된 $MnO_2$와 Mn 복합 산화물의 전기전도도를 비교하면 천이금속이 첨가된 복합 산화물의 특성이 우수한 것으로 나타났다.

• Korean Journal of Crystallography
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• v.14 no.1
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• pp.16-23
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• 2003

The electronic structure and chemical bonding of β-MnO₂ were theoretically investigated by DV-X/sub α/ (the discrete variation X/sub α/) method. which is a sort of the first principle molecular orbital method using Hatre-Fock-Slater approximation. The calculations on several cluster models having different sizes were carried out for the determination of a model suited for analyzing bulk state. The Mn/sub 15/O/sub 56/ model was selected as a sufficiently suitable model for the calculation of electronic state and chemical bonding by the comparison of the calculated XPS (X-ray photo-electron spectrum) and experimentally measured XPS. By using this model, the electron energy level, the density of state, the bond overlap population, the charge density distribution, and the net ionic transfer between cations and anions were calculated and discussed.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.571-576
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• 2007

Manganese-Coated Sand(MCS) prepared with three different methods were applied in the treatment of soluble $Mn^{2+}$ in batch and column experiments. In the bench-scale MCS preparation, the coating efficiency of manganese on the surface of sand increased as the dosage of initial Mn(II) increased. The removed amount of the soluble $Mn^{2+}$ by MCS increased as the solution pH increased, following a typical anionic-type adsorption. The removed amounts of the soluble $Mn^{2+}$ through adsorption was quite similar over the entire pH range, without depending on the contents of Mn on the surface of sand as well as coating methods. When NaClO was used an oxidant, the removed amount of the soluble $Mn^{2+}$ by MCS increased as the concentration of NaClO increased, This trend might be explained by the increased removal efficiency through coating of manganese oxides produced from oxidation of the soluble $Mn^{2+}$ by NaClO on the surface of MCS. From the bench-scale column experiments, the breakthrough of $Mn^{2+}$ occurred after 4,100 bed volume without presence of NaClO while 1.6-times delayed breakthrough of $Mn^{2+}$ was observed in the presence of NaClO. This result also supports that the removal efficiency of the soluble $Mn^{2+}$ could be enhanced by using NaClO.

• Journal of the Mineralogical Society of Korea
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• v.17 no.4
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• pp.309-325
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• 2004

The Cannington Ag-Pb-Zn deposit, northwest Queensland, Australia developed around the host rocks composing banded and migmatitic gneisses, sillimanite-garnet schist and amphibolite. Three crystal habits of sillimanite, gahnite (Zn-spinel) and garnet porphyroblasts occurred on the host rocks of the Cannington deposit could be used to delineate metamorphism that closely associated with Zn-mineralization in the deposit. Linkages the metamorphism to Zinc-mineralization is determined in four chemical systems, KFMASH (K$_2$O-FeO-MgO-Al$_2$O$_3$-SiO$_2$-$H_2O$), KFMASHTO (K$_2$O-FeO-MgO-Al$_2$O$_3$-SiO$_2$-$H_2O$-TiO$_2$-Fe$_2$O$_3$), NCKFMASH (Na$_2$O-CaO-K$_2$O-FeO-MgO-AlO$_3$-SiO$_2$-$H_2O$) and MnNCK-FMASH (MnO-Na$_2$O-CaO-K$_2$O-FeO-MgO-AlO$_3$-SiO$_2$-$H_2O$), using THERMOCALC program (version 3.1; Powell and Holland 1988). Partial melting in MnNCKFMASH and NCKFMASH systems occurs at lower temperature than in the KFMASH and KFMASHTO systems. The partial melting temperature decreases with increasing of Na/(Na+Ca+K) of the bulk rock compositions in the MnNCKFMASH system. The host rocks have melted ca 15 vol.% in the MnNCKFMASH system at peak metamorphic conditions (634$\pm$62$^{\circ}C$ and 4.8$\pm$1.3 kbar), but partial melting have not occurred in KFMASHTO system. Based on calculations of sillimanite isograd in different systems and sillimanite modal pro-portion, prismatic and rhombic sillimanite and gahnite porphyroblasts including prismatic sillimanite inclusion probably have resulted from pressure and temperature increasing through partial melting (from 550～$600^{\circ}C$, 2.0～3.0 kbar to 700～75$0^{\circ}C$, 5.0～7.0 kbar), furthermore have experienced N-S then W-E crustal shortening during D$_1$ and D$_2$ deformation. Consequently, Zinc mineralization related to gahnite growth occurred during D$_2$ and was redistributed and upgraded by partial melting and retrograde metamorphism into structural and rheological sites during shearing in D$_3$.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1462-1464
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• 1997

The spinel $LiMn_2O_4$ has been synthesized by solid-state reaction. $LiMn_2O_4$ which includes 3 mix $Li_2CO_3$ or $LiNO_3$ and $MnO_2$ prepared by Prelim heating at $350^{\circ}C$ for 24hr. $LiMn_2O_4$ fired at temp range from $600^{\circ}C$ to $800^{\circ}C$ for 48hr. The structure a electrochemical characteristics of spinel $LiMn_2O_2$ wh fabricated by changing sintering condition from st materials are investigated. The spinel $LiMn_2O_4$ prepared by the mixture of L CMD at $800^{\circ}C$ for 48hr showed an initial charge ca of 146mAh/g. The spinel $LiMn_2O_4$ prepared by the m of $LiNO_3$/CMD at $600{\sim}800^{\circ}C$ for 48hr stabilized ch discharge capacity after 50th cycles.

• The Journal of the Petrological Society of Korea
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• v.12 no.3
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• pp.110-118
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• 2003

Olivine from the Layered Series (LS), Upper Border Series (UBS), and Marginal Border Series (MBS) of the Skaergaard intrusion was analyzed to examine compositional variation. In general, olivine from all three series shows similar trends in major elements with differentiation: FeO＊ (total iron as FeO＊), Ti $O_2$, and MnO in the olivine, progressively increase, MgO and $SiO_2$progressively decrease, and Na$_2$O, K$_2$O, A1$_2$ $O_3$, CaO, and P$_2$O$\_$5/ remain unchanged at low abundances. No abrupt changes in the trends of major components in Skaergaard olivine are observed. The systematic compositional variations in Skaergaard olivine during differentiation preclude the possibility of any injection of new magma into the chamber during differentiation. Abrupt change in MnO, however, is observed in Skaergaard olivine during differentiation. MnO in Skaergaard olivine steadily increases with differentiation from LZ to UZc and then decreases in UZc of the LS and its equivalents of the MBS and UBS. The decrease of MnO in Skaergaard olivine during the final stage of differentiation is attributable to the abrupt and extensive appearance of ferrobustamite as a liquidus phase.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.1
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• pp.1-16
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• 2023

A non-rare earth-based strontium-aluminate red light emitting phosphor was synthesized by a solid-state reaction method and the effect of synthesis temperature and Mn⁴⁺ activator concentration on the photoluminescence characteristics of the phosphor was studied. The synthesized SrAl₂O₄:Mn⁴⁺ phosphor showed broad band absorption characteristics in the near-ultraviolet and blue regions with peaks at wavelengths of near 330 and 460 nm, and a triple band deep red emission consisted of three peaks at near 644, 658, and 673 nm. The SrAl₂O₄:Mn⁴⁺ phosphor synthesized at a temperature 1600℃ and a Mn⁴⁺ activator concentration of 0.5 mol% showed the strongest PL emission intensity, and concentration quenching was observed at concentrations higher than 0.7 mol%. FE-SEM and DLS particle size distribution analysis showed that the synthesized SrAl₂O₄:Mn⁴⁺ phosphor had a particle size distribution of 2~6.4 ㎛ and an irregular spherical shape with an average particle size of ~4 ㎛.

• Journal of Ceramic Processing Research
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• v.20 no.1
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• pp.80-83
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• 2019

The Mn4+-activated Li2ZnSn2O6 (LZSO:Mn4+) red phosphors were synthesized by the solid-state reaction at temperatures of 1100-1400 ℃ in air. The synthesized LZSO:Mn4+ phosphors were confirmed to have a single hexagonal LZSO phase without the presence of any secondary phase formed by the Mn4+ addition. With near UV and blue excitation, the LZSO:Mn4+ phosphors exhibited a double band deep-red emission peaked at ~658 nm and ~673 nm due to the 2E → 4A2 transition of Mn4+ ion. PL emission intensity showed a strong dependence on the Mn4+ doping concentration and the 0.3 mol% Mn4+-doped LZSO phosphor produced the strongest PL emission intensity. Photoluminescence emission intensity was also found to be dependent on the calcination temperature and the optimal calcination temperature for the LZSO:Mn4+ phosphors was determined to be 1200 ℃. Dynamic light scattering (DLS) and field-effect scanning electron microscopy (FE-SEM) analysis revealed that the 0.3 mol% Mn4+-doped LZSO phosphor particles have an irregularly round shape and an average particle size of ~1.46 ㎛.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.4
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• pp.341-349
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• 2002

Electrical, mechanical and sinterability properties of yttria-stabilized zirconia doped with 5.35wt% $Y_2$O$_3$(Y$_2$O$_3$- containing stabilized zirconia : YSZ) were studied as a function of $Al_2$O$_3$, CoO, Fe$_2$O$_3$ and MnO$_2$ addition. The ratio of monoclinic phase to tetragonal phase was changed by the addition of $Al_2$O$_3$, CoO, Fe$_2$O$_3$ and MnO$_2$ to 8.00 wt% and sintered density decreased with increasing $Al_2$O$_3$, CoO, Fe$_2$O$_3$ and MnO$_2$ addition. Fracture toughness increased with the increase of monoclinic to tetragonal phase ratio and was maximum at about 18%. When transition metals such as CoO, Fe$_2$O$_3$ or MnO$_2$ was added more than 1.5 wt%, the electrical conductivity of YSZ increased. But $Al_2$O$_3$ hardly affected the electrical conductivity of YSZ. The addition of $Al_2$O$_3$, CoO, Fe$_2$O$_3$ and MnO$_2$ into YSZ resulted in the more complex behavior of fracture toughness and hardness variation and the specimen with 1.5wt%-Fe$_2$O$_3$, 3.0wt%-Al$_2$O$_3$ and 1.5wt%-CoO showed the monoclinic to tetragonal phase ratio of 18% and the highest toughness of 10.8 MPa.m$^{1}$2/ and Vickers hardness of 1201 kgf/mm$^2$.