• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.351-354
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• 1998

The formation of the $YBa_2Cu_30_{7_\delta}$(Y123) thick films has been investigated by a surface diffusion Imcess between $3BaCu0_2$+2CuO composite coating powder and a $Y_2BaCuO_5$(Y211). This reaction has been studied in the temperature of $930^{\circ}C$ and $940^{\circ}C$ for 2h to 10h in an oxygen atmosphere. The Y211 substrates becomes covered by co-precipitation of Y123 grains and CuO inclusions. X-ray diflractotnctn. revealed that the lager consisted of an orthorhombic crystal structure. The maximum Jc of $400A/\textrm{cm}^2$ is abtained when the specimen was heat-treated at $930^{\circ}C$ for 6h on the Y211 substrate.

• Journal of the Korean Ceramic Society
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• v.27 no.3
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• pp.423-429
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• 1990

YBa2Cu3Ox ceramics superconductors fabricated using solid state reaction usually contain second phases, such as BaCuO2 and CuO. These second phases are located long the grain boundaries and enhance the abnormal growth of YBa2Cu3Ox grains and, consequently, generate the microcracks. These second phaases were reduced by adding Y2BaCuO5 into solid state reacted YBa2Cu3Ox ceramics. Y2BaCuO5 reacts with grain boundary second phases and reduces the grian size of the ceramics. It was observed the critical current density was improved by adding Y2BaCuO5 into solid state reacted YBa2Cu3Ox ceramic superconductor.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.2
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• pp.148-156
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• 1994

Three composition in the system of $YO_{1.5}-BaO-CuO$ were grown using a cold crucible (skull) melting technique with a 50 kW R.F. induction generator operating at 4 MHz as the power source. The starting materials were prepared by conventional ceramic powder processing methods, loaded into the skull, and melted at about $1200^{\circ}C$. For this study, compositions near the $YBa_2Cu_3O_X$ region were selected. The growth rates used ranged from 4 cm/hr to 0.25 cm/hr. The relation between the microstructures and the starting composition of each ingot was determined using metallograph, X-ray diffraction, and energy dispersive X-ray analysis. Both $YBa_2Cu_3O_X$ and $Y_2BaCuO_5$ needle-shaped crystals, aligned with the growth direction, were formed in the $CuO-BaCuO_2$ eutectic matrix of the $YBa_2Cu_7O_x and YBa_5Cu_{11}O_x$ ingot.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.493-501
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• 1998

$YBa_2Cu_3O_X$ samples were fabricated by MPMG(Melt Powdered Melt Growth). Intitial composition of the mixed powders were prepared as follow ; $YBa_2Cu_3O_X$ : $Y_2BaCuO_5$ = 1:0, 1:0.2, 1:0.3, 1:0.4. After the first melt and cooling, 5wt% to 20wt% fo Ag power was added to the powder. Effects of the different initial $Y_2BaCuO_5$ and Ag addition amount on $J_c$ and magnetization of $YBa_2Cu_3O_X$ fabricated by MPMG method were investigated. The critical current density increased with the amount of $Y_2BaCuO_5$ and Ag. It was also observed that the difference between negative and positive magnetization in the magnetization hysteresis measurement at 77K was larger than the case where $Y_2BaCuO_5$and Ag were not added to the $YBa_2Cu_3O_X$ powders. It is concluded that $Y_2BaCuO_5$ sample with 40wt% amount of $Y_2BaCuO_5$ and 20wt% amount of Ag has not only the largest $J_c$ but also the improved pinning effect.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.415-422
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• 1986

The metal-support interaction of copper oxide supported on ${\gamma}$-alumina and silica was studied by X-ray diffraction (XRD) and temperature-programmed reduction(TPR). It was found that XRD pattern of CuO can not be observed up to 5.0wt % copper content for CuO/${\gamma}-Al_2O_3$ while CuO/$SiO_2$ sample shows the CuO pattern even at 2.5wt% copper content. $H_2-$TPR of CuO/${\gamma}-Al_2O_3$ system shows four major peaks at 145${\circ}C$, 185${\circ}C$, 210${\circ}C$, and 250${\circ}C$. In the case of CuO/$SiO_2$, a large peak at 250${\circ}C$ was appeared accompanying a small peak at 425${\circ}C$. Comparing the TPR peaks with that of copper aluminate which was prepared from the calcination of CuO/${\gamma}-Al_2O_3$ at 1000${\circ}C$, the peaks at around 145${\circ}C$, 200${\circ}C$ (185${\circ}C$ and 210${\circ}C$), and 250${\circ}C$ were corresponded to $Cu^+$ ion in CuO interacting ${\gamma}-Al_2O_3$, $Cu^+$ ions in defect sites of ${\gamma}-Al_2O_3$ and $Cu^{2+}$ ion in the bulk CuO layer, respectively. From the results, it was concluded that there is considerable metal-support interaction in CuO on ${\gamma}-Al_2O_3$ and the interaction results in a stabilization of $Cu^+$ ion in the system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.7
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• pp.347-351
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• 2004

The $ZnNb_2O_{6}$ ceramics with CuO(1, 3, 5wt%) were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of $950^{\circ}C$∼$1075^{\circ}C$ for 3hr in air The structural properties and the microwave dielectric properties of $ZnNb_2O_{6}$ ceramics were investigated with sintering temperature and the addition of CuO. Increasing the addition of CuO, the peak of second phase($Cu_3Nb_2O_{8}$) was increased. The grain size of the $ZnNb_2O_{6}$ ceramics with CuO was increased with CuO addition at same temperature. The dielectric constant of $ZnNb_2O_{6}$ ceramics with CuO was increased with sintering temperature and CuO addition. While the quality factor of the $ZnNb_2O_{6}$ ceramics with lwt% CuO depended on sinterability, the quality factor of $ZnNb_2O_{6}$ with 3wt% and 5wt% CuO depended on second Phase due to the CuO addition. The optimum dielectric Properties of $\varepsilon$$_{r}$ = 21.73 Q${\times}$f = 19,276 were obtained from the condition of 3wt% CuO addition and sintering temperature of $1025^{\circ}C$(3hr).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.593-596
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• 2003

A proposed way to prepare $YBa_2Cu_3O_y$ wires or tapes is that Ag is used as substrate and melting point of $YBa_2Cu_3O_y$ is decreased to lower than the melting point of silver ($961\;^{\circ}C$). Therefore after the deposition of $YBa_2Cu_3O_y$ film on Ag substrate, the heat treatment can be carried out below the Ag melting point. Silver (Ag) and Lead oxide(PbO) were selected to be additives for $YBa_2Cu_3O_y$. Different Ag and PbO contents were added in $YBa_2Cu_3O_y$, the melting points of which were measured by DTA. In order to guarantee that the superconductivity of $YBa_2Cu_3O_y$ was not reduced after Ag and PbO added into $YBa_2Cu_3O_y$, their superconductivities were measured. It is proved that as additives, both Ag and PbO can reduce the melting point of $YBa_2Cu_3O_y$. For Ag doped $YBa_2Cu_3O_y$, $T_c$ is about 93K and ${\Delta}Tc$ is $2{\sim}3K$. For PbO doped $YBa_2Cu_3O_y$, $T_c$ is $88K{\sim}92K$ and ${\Delta}T_c$ is $11{\sim}12K$. When 10 wt% of Ag and 10 wt% PbO were added in $YBa_2Cu_3O_y$, the melting point of the mixture of $YBa_2Cu_3O_y$ (80 wt%), Ag (10 wt%) and PbO (l0 wt%) is $943^{\circ}C$. The transition temperatures ($T_c$) of the sample is 91.8 K.

• Journal of the Korean institute of surface engineering
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• v.51 no.4
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• pp.243-248
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• 2018

All solid state thin film batteries with two types of cell structure, Pt / $LiCoO_2$ / LiPON / Cu and Pt / $LiCoO_2$ / LiPON / $LiCoO_2$ / Cu, are prepared and their electrochemical performances are investigated to evaluate the effect of $LiCoO_2$ interlayer at the interface of LiPON / Cu. The crystallinity of the deposited $LiCoO_2$ thin films is confirmed by XRD and Raman analysis. The crystalline $LiCoO_2$ cathode thin film is obtained and $LiCoO_2$ as the interlayer appears to be amorphous. The surface morphology of Cu current collector after cycling of the batteries is observed by AFM. The presence of a 10 nm-thick layer of $LiCoO_2$ at the interface of LiPON / Cu enhances the interfacial adhesion and reduces the interfacial resistance. As a result, Li plating / stripping at the interface of LiPON / Cu during charge/discharge reaction takes place more uniformly on Cu current collector, while without the interlayer of $LiCoO_2$ at the interface of LiPON / Cu, the Li plating / stripping is localized on current collector. The thin film batteries with the interlayer of $LiCoO_2$ at the interface of LiPON / Cu exhibits enhanced initial coulombic efficiency, reversible capacity and cycling stability. The thickness of the anode current collector Cu also appears to be crucial for electrochemical performances of all solid state thin film batteries.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.543-546
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• 2004

The melting temperature and critical temperature(Tc) of $YBa_2Cu_3O_x$ with deferent content impurities of PbO and $BaPbO_3$ were studied. When the PbO was used as addition in $YBa_2Cu_3O_x$, although the melting point could be reduced, the superconductivity(the transition width, ${\Delta}T_c$) became poor. From the XRD pattern of the sintered mixture of $YBa_2Cu_3O_x$ and PbO it was known that there is a reaction between $YBa_2Cu_3O_x$ and PbO, and the product is $BaPbO_3$. In the process of the reaction the superconducting phase of $YBa_2Cu_3O_x$ was decreased and in the sample $BaPbO_3$ became the main phase. Therefore the superconductivity was reduced. $BaPbO_3$ was chosen as the impurity for the comparative study. The single phase BaPbO3 was synthesized by the simple way from both mixtures of $BaPbO_3$ and PbO, $BaPbO_3\;and\;PbO_2$. Deferent contents of $BaPbO_3$(10%, 20%, 30%) were added in the $YBa_2Cu_3O_x$. By the phase analysis in the XRD patterns it was proved that there werenot reactions between $YBa_2Cu_3O_x$ and $BaPbO_3$. When $BaPbO_3$ was used as impurity in $YBa_2Cu_3O_x$ the superconductivity was much better than PbO as impurity in $YBa_2Cu_3O_x$. But the melting point of $YBa_2Cu_3O_x$ with $BaPbO_3$ could not be found when the temperature was lower than $1000^{\circ}C$ in the DTA measurement.

• Journal of Powder Materials
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• v.20 no.2
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• pp.114-119
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• 2013

In the DBC (direct bonding of copper) process the oxygen partial pressure surrounding the AlN/Cu bonding pairs has been controlled by Ar gas mixed with oxygen. However, the direct bonding of Cu with sound interface and good adhesion strength is complicated process due to the difficulty in the exact control of oxygen partial pressure by using Ar gas. In this study, we have utilized the in-situ equilibrium established during the reaction of $2CuO{\rightarrow}Cu_2O$ + 1/2 $O_2$ by placing powder bed of CuO or $Cu_2O$ around the Cu/AlN bonding pair at $1065{\sim}1085^{\circ}C$. The adhesion strength was relatively better in case of using CuO powder than when $Cu_2O$ powder was used. Microstructural analysis by optical microscopy and XRD revealed that the interface of bonding pair was composed of $Cu_2O$, Cu and small amount of CuO phase. Thus, it is explained that the good adhesion between Cu and AlN is attributed to the wetting of eutectic liquid formed by reaction of Cu and $Cu_2O$.