• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.50-54
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• 1999

We have measured the x-ray photoemission spectroscopy of cation deficient La0.970Mn0.970O3 as a function of temperature. Detailed results on the chemical shifts and changes in Mn 2p and Lp 3d core levels due to variation of temperature have been obtained. The Mn 2p 3/2 and 1/2 main peaks and La 3d core spectrum shift to lower binding energy levels with increasing temperature. This XPS behavior is correlated with the strength of localization of Mn3+. The Jahn-Teller effect due to Mn3+ besides the conventional random potential effects is likely to localize charge carriers in La-.970Mn0.970O3.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.684-688
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• 2001

The structural, piezoelectric and dynamic range characteristics of modified PbTi $O_3$ceramics were investigated as a function of Mn $O_2$addition. With the increase of Mn $O_2$addition, Curie temperature was decreased. As the increase of Mn $O_2$addition, mechanical quality factor ( $Q_{mt3}$) in the third over tone thickness mode was increased. Dynamic range in the third over tone thickness mode was also increased with the increase of Mn $O_2$addition. The composition ceramics added to 0.075wt% Mn $O_2$showed the best properties for SMD type resonator using third over tone thickness vibration in terms of high Curie temperature more than 31$0^{\circ}C$ and dynamic range of 49.38dB.B.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.552-555
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• 1995

The magnetic properties of Mg-Mn ferrites were investigated in the composition range of $Mg_{a}Mn_{b}Fe_{c}O_{4\pm\delta}$ (a+b+c=3) with the addition of $Al_{2}O_{3}$. In $MgO-MnO-Fe_{2}O_{3}$ ternary system, the spinel single phase existed within the composition range of MgO-50 mol%, MnO-70 mol% and $Fe_{2}O_{3}-60\;mol%$. The saturation magnetic flux density increased with the increase of $Fe_{2}O_{3}$ content and showed the maximum at the stoichiometric composition of $(Mg,Mn)Fe_{2}O_{4}$. In $Mg_{x}Mn_{1-x}Fe_{2}O_{4}(x=0.2~0.8)$ system, the saturation magnetic flux density showed the maximum at $Mg_{0.2}Mn_{0.8}Fe_{2}O_{4}$. The addition of $Al_{2}O_{3}$ resulted in the decrease of saturation magnetic flux density but increased the electrical resistivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.474-477
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• 2001

The properties of LiMnO$_2$ was studied as a cathode active material for lithium polymer batteries. LiMnO$_2$ cathode active materials were synthesized by the reaction of LiOH . $H_2O$ and Mn$_2$O$_3$at various temperature under argon atmosphere. For lithium polymer battery applications, the LiMnO$_2$cell was characterized electrochemically by charge-discharge experiments and a.c. impedance spectroscopy. And the relationship between the characteristics of powders and electrochemical properties was studied in this research. A maximum discharge capacity of 160-170 mAh/g for ο-LiMnO$_2$ cell was achieved. Used that SP270 as electric active material in LiMnO$_2$, it is excellent than property of electric active material used Acetylene black or KS6 at charge/discharge capacity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.541-544
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• 2001

Orthorhombic $LiMnO_2$ was synthesized by solid-state reaction using $LiOH{\cdot}H_{2}O$ and $Mn_{2}O_{3}$ as starting material. Its electrochemical properties as cathode in lithium batteries were examined. X-ray diiffraction revealed that the $LiMnO_2$ compound showed a well-defined orthorhombic phase of a space group with Pmnm. The capacity of $LiMnO_2$ agreed well with its specific surface area and grinding treatment was effective in improving cycling performance. For lithium polymer battery applications. the $LiMnO_2$ cell was characterized electrochemically by charge-discharge experiments. And the relationship between the characteristics of powder and electrochemical properties was studied in this research. A maximum discharge capacity of $160-170mAhg^{-1}$ for $LiMnO_2/Li$ cell was achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.541-544
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• 2001

Orthorhombic LiMnO$_2$ was synthesized by solid-state reaction using LiOH$.$H$_2$O and Mn$_2$O$_3$ as starting material. Its electrochemical properties as cathode in lithium batteries were examined. X-ray diffraction revealed that the LiMnO$_2$ compound showed a well-defined orthorhombic phase of a space group with Pmnm. The capacity of LiMnO$_2$ agreed well with its specific surface area and grinding treatment was effective in improving cycling performance. For lithium polymer battery applications, the LiMnO$_2$ cell was characterized electrochemically by charge-discharge experiments. And the relationship between the characteristics of powder and electrochemical properties was studied in this research. A maximum discharge capacity of 160-170mAhg$^{-1}$ for LiMnO$_2$/Li cell was achieved

• Journal of the Korean Chemical Society
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• v.20 no.5
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• pp.431-437
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• 1976

On the condition of adequate air supply, complete removal of carbon monoxide,occurred above $650^{\circ}C$. Using catalysts, the oxidation of carbon monoxide occurred at lower temperatures; on both $MnO_2 \;and\;30%\;MnO_2-70%\;CuO\;at\;250{\circ}C,\;on\;CuO\;at\;450{\circ}C,\;on\;50%\;MnO_2-50%\;CuO\;at\;200{\circ}C,\;and\;on\;70%\;MnO_2-30%\;CuO\;at\;180{\circ}C$. Manganese dioxide (p-type) showed higher activity than cupric oxide (n-type) and a catalyst consisting of 60% $MnO_2-40%$ CuO had the highest activity of all the $MnO_2$-CuO mixture. Over the range of transitional temperature, carbon monoxide removal efficiency decreased linearly with increasing inlet carbon monoxide concentration while temperature was fixed. Residence time of gases in the catalytic reactor, in the range of 0.9 to 1.8 seconds, gave no effect on carbon monoxide conversion.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.443-450
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• 2014

Selective catalytic reduction of nitrogen monoxide by hydrogen ($H_2$-SCR of NO) over platinum catalysts impregnated on zirconia-incorporated silica ($ZrO_2-SiO_2$) and manganese oxide ($MnO_x$) was investigated. $Pt-MnO_x$ catalyst showed low conversions and low yields of $N_2O$ and $NO_2$ at $100{\sim}350^{\circ}C$. On the other hand, NO conversions over $Pt/ZrO_2-SiO_2$ were very high, but $N_2O$ was predominantly produced at $100-150^{\circ}C$ and the yield of $NO_2$ increased with temperature at $200-300^{\circ}C$, resulting in poor $N_2$ yields. $Pt-MnO_x/ZrO_2-SiO_2$ exhibited a small enhancement in $N_2$ yield at $100-150^{\circ}C$ due to the synergy of $MnO_x$ and $ZrO_2-SiO_2$. The surface composition and oxidation state of the catalyst components and the acidity of the catalysts were examined. IR spectra of the adsorption of NO and their subsequent reactions with hydrogen on these catalysts were also recorded. The variations of conversion and product yield according to the catalyst components in the $H_2$-SCR of NO were discussed in relation to their catalytic roles.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.92-95
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• 2004

Using the Micro-Pulling Down (${\mu}$-PD), $MnO_2$ and $Tb_4O_7$ co-doped crack-free stoichiometric $LiNbO_3$ single crystals were grown in 1.0 mm diameter and 25-30 mm length for c-axis. The homogeneous distributions of $MnO_2$ and $Tb_4O_7$ concentration were confirmed by the Electron Probe Microanalysis (EPMA). Also, the infrared OH absorption band of the single crystals observed by using a Fourier Transform-Infrared Spectrophotometer (FT-IR) at room temperature and the photoluminescence spectra was measured with respect to the $MnO_2$ and $Tb_4O_7$ doping.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.5
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• pp.362-366
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• 2000

$Li_{0.44}MnO_2$cathode material has high reversibility during lithium insertion processes and is not easily damaged through over-charging or over-discharging. $Mn_2O_3$is often present as an impurity phase, and reduce the electrochemical capacity of electrode because this phase is electrochemically inert. Adding of excess NaOH reduced the $Mn_2O_3$to the content under undetectable by X-ray diffraction. Because the capacity can be increased in the cathode materials with larger unit cell, some of the manganese was replaced with titanium having larger ion size, and powders with the formula $Li_{0.44}T_{iy}Mn_{1-y}O_2$(where y = 0.11, 0.22, 0.33, 0.44, and 0.55) was synthesized and characterized. A maximum reversible capacity of 150 mAh/g was obtained for $Li/P(EO)_8$LiTFSI/$Li_{0.44}Ti_{0.22}Mn_{0.78}O_2$cells in electrochemical potential spectroscopy (ECPS) experiments. Cells with the titanium-doped manganese oxides exhibited a fade rate of 0.12 % or less per cycle.