• Korean Journal of Materials Research
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• v.29 no.2
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• pp.92-96
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• 2019

Transition metal oxide is widely used as a water electrolysis catalyst to substitute for a noble metal catalyst such as $IrO_2$ and $RuO_2$. In this study, the sol-gel method is used to synthesize the $Cu_xCo_{3-x}O_4$ catalyst for the oxygen evolution reaction (OER),. The CuxCo3-xO4 is synthesized at various calcination temperatures from $250^{\circ}C$ to $400^{\circ}C$ for 4 h. The $Cu_xCo_{3-x}O_4$ synthesized at $300^{\circ}C$ has a perfect spinel structure without residues of the precursor and secondary phases, such as CuO. The particle size of $Cu_xCo_{3-x}O_4$ increases with an increase in calcination temperature. Amongst all the samples studied, $Cu_xCo_{3-x}O_4$, which is synthesized at 300?, has the highest activity for the OER. Its onset potential for the OER is 370 mV and the overpotential at $10mA/cm^2$ is 438 mV. The tafel slope of $Cu_xCo_{3-x}O_4$ synthesized at $300^{\circ}C$ has a low value of 58 mV/dec. These results are mainly explained by the increase in the available active surface area of the $Cu_xCo_{3-x}O_4$ catalyst.

• Journal of the Korean Magnetics Society
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• v.6 no.6
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• pp.382-387
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• 1996

The characteristics of the complex permeability of ${(Ni_{x}Cu_{0.2}Zn_{0.8-x}O)}_{1-w}{(Fe_{2}O_{3})}_{1+w}$ with various Ni and $Co_{3}O_{4}$ contents were investigated in this work. It is found that the NiCuZn ferrites with $x{\geq}0.6$ have a relatively small peak width of the imaginary part of permeability $\mu$". The resonance frequency is increased as Ni content becomes higher, where the loss is low. The $\mu$" value decreases with increasing FezO, deficiency, but the resonance frequency($f_{\mu"max}$) is only slightly affected by $Fe_{2}O_{3}$ deficiency. In case of $Co_{3}O_{4}$ addition to the NiCuZn ferrites, the $f_{\mu"max}$ increases since the initial permeability decreases with the amount of $Co_{3}O_{4}$. It is concluded that the Ni content in the NiCuZn ferrite is a dominant factor for the total loss of these spinel ferrites.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.223-228
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• 1998

Glass films of $SiO_2-TiO_2-M_xO_y$ (M = Co, Cr or Cu) have been prepared on soda-lime-silica slide glasses by the chemical solution method using a spin-coating technique. Commercially available tetraethyl orthosilicate, titanium trichloride, and cobalt-, chromium- and copper-nitrates were used as starting materials. No crystalline segregations of $Co_3O_4$, $Cr_2O_3$ and CuO were observed by X-ray diffraction ${\theta}-2{\theta}$ scans. From the optical transmission analysis, cobalt existed as $ Co^{2+}$ in tetrahedral coordination, chromium as $Cr^{6+}$ in tetrahedral symmetry and copper as $Cu^{2+}$ in octahedral coordination. Films with a crack-free and no texture exhibited homogeneous interfaces between the films and the substrates along the cross-section.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.639-644
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• 1996

The $YBa_2Cu_{3-y}Ag_yO_{7-x}$ high-temperature superconductors were prepared by pyrophoric synthetic method from $Y_2O_3$, $BaCO_3$, CuO, and $AgNO_3$ powders. When we were partially substituted Ag for Cu in $YBa_3Cu_3O_{7-x}$, the superconducting properties of $YBa_2Cu_{3-y}Ag_yO_{7-x}$ were investigated with X-ray diffractometer, resisitivity measuring equipment, SEM, and Vickers Hardness. The Tc,zero of $YBa_2Cu_3O_{7-x}$ was 91K, the density was $5.2g/cm^3$, and the hardness was $590kg/mm^2$. When Ag was substituted below y=0.15, electrical property of $YBa_2Cu_{3-y}Ag_yO_{7-x}$ did not change but microstructure, density, and hardness were enhanced.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.2
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• pp.124-131
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• 2007

Methane is partially oxidized to produce the syngas by the lattice oxygen of metal oxides in the absence of gaseous oxygen. The present work deals with ferrite including copper component, which does not chemisorb methane, to investigate the suppression of the carbon deposition during the reduction of metal oxides by methane. Iron-based oxides of $Cu_xFe_{3-x}O_4$(X=0.25, 0.5, 1.0) was synthesized by the co-precipitation method. Thermogravimetric Analysis(TGA) was used to observe the isothermal reduction behavior of $Cu_xFe_{3-x}O_4$ and $Fe_3O_4$ at $600-900^{\circ}C$ under methane atmosphere. The crystal structures of reduced specimens were characterized by X-rays powder diffraction(XRD) technique. From the analyses of TGA, it is concluded that the reduction kinetics of $CuFe_2O_4$ was the fastest among $Fe_3O_4$ and $Cu_xFe_{3-x}O_4$(X=0.25, 0.5, 1.0). The X-ray diffraction analyses indicated that $Cu_xFe_{3-x}O_4$ was decomposed to Cu and $Fe_3O_4$ phase at $600^{\circ}C$ and was reduced to Cu and Fe phase at $800^{\circ}C$. $Fe_3O_4$, which was reduced at $900^{\circ}C$, showed Fe, graphite and $Fe_3C$ phases. On the contrary, $Cu_xFe_{3-x}O_4$ does not show the graphite or $Fe_3C$ phases. This results infer that Cu component suppress the carbon deposition on Cu-ferrite.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.713-716
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• 2001

In many papers, the electrochemical analysis of LiMn$_2$O$_4$shows the transition results of Mn$^{3+}$ ion. Charge ordering is accompanied by simultaneous orbital ordering due to the Jahn-Teller effect in Mnl$^{3+}$ ions. To analyze the cycle performance of LiMn$_{2-x}$Cu$_{x}$ O$_4$as the cathode of 4 V class lithium secondary batteries, XRD, TGA analysis were conducted. Although the cycle performance of the LiMn$_{2-x}$Cu$_{x}$ O$_4$was improved from pure LiMn$_2$O$_4$, the discharge capacity was significantly lower than LiCoO$_2$. In this paper, We study the Electrochemical characterization and enhanced stability of Cu-doped spinels in the LiMn$_{2-x}$Cu$_{x}$ O$_4$upon initial cycling.l cycling.

• Clean Technology
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• v.26 no.4
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• pp.286-292
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• 2020

This study confirmed the effect of the Cu/CeO2-X catalyst on the CO oxidation activity at low temperature through the catalyst's structure and reaction characteristics. The catalyst was prepared by the wet impregnation method. Cu/CeO2_X catalysts were manufactured by loading Cu (active metal) using CeO2 (support) formed at different calcination temperatures (300-600 ℃). Manufactured Cu/CeO2_X catalysts were evaluated for the low-temperature activity of carbon monoxide. The Cu/CeO2_300 catalyst showed an activity of 90% at 125 ℃, but the activity gradually decreased as the calcination temperature of the CeO2-X and Cu/CeO2_600 catalysts showed an activity of 65% at 125 ℃. Raman, XRD, H2-TPR, and XPS analysis confirmed the physicochemical properties of the catalysts. Based on the XPS analysis, the lower the calcination temperature of the CeO2 was, the higher the unstable Ce3+ species (non-stoichiometric species) ratio became. The increased Ce3+ species formed a solid solution bond between Cu and CeO2-X, and it was confirmed by the change of the CeO2 peak in Raman analysis and the reduction peak of the solid solution structure in H2-TPR analysis. According to the result, the formation of the solid solution bond between Cu and Ce has been enhanced by the redox properties of the catalysts and by CO oxidation activity at low temperatures.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.41-47
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• 2020

The effect of Co interlayer on the interfacial reliability of SiN_x/Co/Cu thin film structure for advanced Cu interconnects was systematically evaluated by using a double cantilever beam test. The interfacial adhesion energy of the SiN_x/Cu thin film structure was 0.90 J/㎡. This value of the SiN_x/Co/Cu thin film structure increased to 9.59 J/㎡.Measured interfacial adhesion energy of SiN_x/Co/Cu structure was around 10 times higher than SiN_x/Cu structure due to CoSi₂ reaction layer formation at SiN_x/Co interface, which was confirmed by X-ray photoelectron spectroscopy analysis. The interfacial adhesion energy of SiN_x/Co/Cu structure decreased sharply after post-annealing at 200℃ for 24 h due to Co oxidation at SiN_x/Co interface. Therefore, it is required to control the CoO and Co₃O₄ formation during the environmental storage of the SiN_x/Co/Cu thin film to achieve interfacial reliability for advanced Cu interconnections.

• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.19-24
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• 1997

Composition and process conditions for low temperature sintered NiCuZn ferrites were investigated, so as to fabricate multilayered chip inductor. The$Fe_2O_3$ deficiency for low temperature sintering was decreased with NiO contents of NiCuZn ferrites. The permeability of NiCuZn ferrites can be controlled in the range of 12~562 with the variation of NiO and $Co_3O_4$ contents. The $Q_{max} $ frequency of NiCuZn ferrites was decreased from 50 MHz to 3 MHz linearly with permeability increase from 60 to 560. The relation between the $Q_{max}$ frequency(Y) and permeability(X) of NiCuZn ferrites was expressed with the following empirical equation, logY=4.2-1.4logX.

• Journal of the Korean Applied Science and Technology
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• v.15 no.4
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• pp.79-85
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• 1998

$Cu_xFe_{3-x}O_4$ catalyst and $Zn_xFe_{3-x}O_4$ catalyst were synthesized by the air oxidation method with various C(II) and Zn(II) weights. Activated catalysts decomposed carbon dioxide to carbon at $350^{\circ}C$, $380^{\circ}C$, $410^{\circ}C$ and $440^{\circ}C$. The value of carbon dioxide decomposition rate for $Cu_{0.003}Fe_{2.997}O_4$ and $Zn_{0.003}Fe_{2.997}O_4$ catslysts than was better catalysts. The decomposed rate of the catalysts is about 85%${\sim}$90%. The reaction rate constant(4.00 $psi^{1-{\alpha}}/min$) and activation energy(2.62 kcal/mole) of $Cu_{0.003}Fe_{2.997}O_4$ catalyst are better than $Zn_{0.003}Fe_{2.997}O_4$