• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.124.1-124.1
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• 2008

• Journal of the Korean Ceramic Society
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• v.28 no.3
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• pp.243-251
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• 1991

High-Tc YBa2Cu3O7-x superconducting thin films have been prepared by single-target off-axis RF magnetron sputtering. Optimal ratio of Y : Ba : Cu of the single-target was determined as 1 : 1.65 : 3.35 in order to obtain the stoichiometric films. Tc, crystalline phase, and microstructures of the surface and cross-section of the ex-situ YBa2Cu3O7-x thin films on MgO(100) had a Tc, zero of 80K, and the films on LaAlO3/Si had a Tc, on-set of 90 K and a Tc, zero of 70 K.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.4
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• pp.210-218
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• 2000

For the fabrication of $YBa_2Cu_3O_x$ thick film, a substrate of $Y_2BaCuO_5$ was fabricated by adding $CeO_2$ into $Y_2BaCuO_5$ and two types of doping materials added with binder material were prepared. Each doping material was patterned on $Y_2BaCuO_5$substrate by the screen printing method and then was annealed at the temperature with a few step. It could be observed by X-ray diffraction patterns and SEM photographs that through the diffusion process of the $Y_2BaCuO_5$ and each doping material, the $YBa_2Cu_3O_x$ phase was formed. And with n additive of $CeO_2$ the thickness of formed $YBa_2Cu_3O_x$decreased. From the experiment of current limiting on thick film, the sample with thiner thickness of $YBa_2Cu_3O_x$ showed the more effective characteristics of current limiting.

• Korean Journal of Crystallography
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• v.5 no.2
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• pp.85-92
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• 1994

Ferroelectric Bi4Ti3012 thin films have been grown on LaAlO(001) by Pulsed-laser deposition. Phase formation and structural films prepared of the films prepared at varigus deposition temperatures are investigated using x-ray diffraction The film grown at 740℃ shows epitaxial growth behavior with c-akis normal to the substrate. N2tBmstiucCures of Bi4Ti3012/YBa2Cu307-x/LaAIO3(001) have been in-situ grown. Even though the a-and b-axes of the Yba2Cu307-x layer show epitaxial growth behavior.

• Bulletin of the Korean Chemical Society
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• v.9 no.4
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• pp.240-243
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• 1988

Degradation of the 90 K superconductor $YBa_2Cu_3O_{7-{\delta}}$ in water and humid atmosphere were studied and its decomposition products were identified as $BaCO_3$, CuO, $Y_2(CO_3)_3{\cdot}3H_2O$ and $O_2$. XRD analysis, iodometric titration and IR-spectroscopy of the degraded samples suggest that the $YBa_2Cu_3O_{7-{\delta}}$ decomposes in three steps such as the reduction of $Cu^{3+}$ to $Cu^{2+}$, followed by the hydroxylation of $Ba^{2+}$ and $Y^{3+}$ via hydration and finally the formation of carbonates through the uptake of ambient $CO_2$.

• Transactions on Electrical and Electronic Materials
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• v.10 no.1
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• pp.31-34
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• 2009

The improvement of preparation process of ${YBa_2}{Cu_3}{O_x}$ superconductor and its conducting properties is important for practical applications. In this study, the additives such as $Ag_{2}O$ and PbO were used to improve the preparation conditions of ${YBa_2}{Cu_3}{O_x}$ superconducting bulk samples and the properties of ${YBa_2}{Cu_3}{O_x}$ superconductors prepared with powders using sol-gel method and solid state reaction method were studied. The effects of the different powders and the additives to the density, grain alignment, and porosity of samples, that affect the critical current density of superconductor, also have been investigated. It is found that the properties of ${YBa_2}{Cu_3}{O_x}$ prepared with sol-gel synthesized powder and the additives showed better superconductivities than those of conventionally prepared superconductors.

• Journal of Powder Materials
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• v.7 no.4
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• pp.205-211
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• 2000

Distribution of $Y_2BaCuO_5$ (211) Particles within $YBa_2Cu_3O_{7-x}/$ (123) grains of melt infiltration processed YBCO oxides was investigated. Processing parameters were a temperature, atmosphere (air and $O_2$) and initial 211 size. The 211 particles were distributed randomly within the 123 grains when the initial 211 size was large, while they made x-like pattern and/or butterfly-like patterns when the 211 size was small. The 211 patterns were more clearly observed in the samples prepared at higher temperatures and under $O_2$ atmosphere. The 211 distribution was explained in terms of the interfacial energy relationship among the solid, particle and melt.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.40-45
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• 1995

직경 2인치의 YBa2Cu3O7-y 타겟을 사용하여 높은 스퍼터링 기체 압력 하에서 off-axis DC-마그네트론 스퍼터링 방법으로 MgO(100) 단결정 기판 위에 YBa2Cu3O7-y 박막을 c축 방향으로 in-냐셔 성장시킬 때 기판의 접지 여부와 인가전류의 양이 박막 성장에 미치는 여향을 연구하였다. 그 결과 접지 여부는 박막의 초전도 변환온도, 전기수송 특성, 결정 구조적 특성에는 영향을 거의 주지 않는 반면 표면상태에는 상당한 영향을 미치며, 인가전류의 양은 초전도 특성에 많은 영향을 미침을 발견하였다. 기판온도 $670^{\circ}C$, 스퍼터링 기체압력 300mTorr, 아르곤 대 산소 분압비 5:1의 조건에서 인가전류의 최적량은 300-500 mA이었으며 평균 박막 성장속도는 $0.11-0.14AA$/s로 매우 낮았다. 기판의 접지 효과와 낮은 성장속도의 원인에 대해 고찰해 본다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.229-237
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• 1996

The superconducting phase, $YBa_{2}Cu_{3}O_{x}$ (YBCO), was in-situ deposited on the single crystal MgO substrates, using an aerosol decomposition process in a cold plasma reactor. The solubility and decomposition temperature of the chemical precursors, and the vapor pressures of the solvents, were determined to be the factors crucial to achieving a stoichiometric, crystalline YBCO phase. The deposition parameters for the YBCO phase were 0.3 to 2.7 kPa for the oxygen partial pressure and $800^{\circ}C$ to $940^{\circ}C$ for the substrate temperature. The optimum deposition conditions for the YBCO phase were observed along the CuO decomposition line.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.818-823
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• 1992

2-Ethylhexanoate compounds which contained Y, Er, Yb, Ba, and Cu were prepared separately. These metallo-organic compounds were dissolved together in the common solvent and the solution was homogeneous. From these solution, high $T_c$ superconductors $YBa_2Cu_3O_{7-\delta}(Y_{123})$, $ErBa_2Cu_3O_{7-\delta}(Er_{123})$, and $YbBa_2Cu_3O_{7-\delta}(Yb_{123})$ were prepared. XRD analysis showed that these superconductors were not single phase and contained some impurity phases including $YBa_2Cu_4O_8(Y_{124})$. This was also confirmed from the magnetic susceptibility measurement. Generally, critical temperatures were higher than that of the superconductors prepared by ceramic method. Volume diamagnetic susceptibility showed little variation compared to the specimen made by ceramic method.